NEOBIOME

D03: Water, Waste & Circular Systems

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typeedt

43 min read

D03: Water, Waste & Circular Systems

Domain framework: edt_framework

Scope

On-site water supply and treatment, waste reduction and material recovery, and circular resource flows. Water is treated as a distinct domain from food (D02) consistent with IPCC WG2, FEW Nexus, and WSR measurement logic. CR_004 CR_005

Key technologies

Rainwater harvesting, greywater recycling, blackwater treatment (constructed wetlands, biodigesters), bore water, desalination (small-scale), water quality monitoring, waste sorting and reduction, material recovery, biochar production, composting, repair and reuse infrastructure, circular economy tracking.

Evidence

  • Stormwater (declared out-of-scope). NES-F 2020 does not regulate general development stormwater (it is a regional-plan / RMA s15 matter with region-specific triggers, REG_036), so the model’s stormwater exclusion is defensible; device costs are minor and per-device (rain-garden maintenance ~3-8/m²/yr, acquisition up to ~2,500/m², OT_223). If the community holds stock, the NES-F stockholding rule applies (sealed base, 50 m setback, effluent management) as a compliance obligation, not a modelled cost.

  • Irrigation storage + crop water (cost + irrigation gaps). Water-storage CapEx splits by type: earth embankment dam ~2.5/m³ construction ([[ot_216_gisborne-aqualinc-dam-cost-2016|OT_216]]) vs lined pond ~5/m³ excavation plus liner (OT_217); the model’s assumed $5/m³ describes a lined pond, and the 3.0 m depth checks out (real ponds run 3-4 m). Applied irrigation = crop water requirement (FAO-56 Kc OT_218; NZ potato 491-611 mm LIT_130) minus the crop-effective share of GIS rainfall (effective-rain method OT_219; NZ daily-balance cross-check, applied demand 170-400 mm/yr OT_220; 80% application efficiency OT_221). The rainfall input stays the GIS regional layer (RD_022).

  • The metric-choice is validated by the field’s own review. A critical review of 80 water-security metrics (107 publications) concludes “the more local the scale and the more specific the water domain, the more meaningful results that the metrics can provide” — i.e. a community-scale, per-domain water measure (the NI water_ssi design) is the defensible choice over a national aggregate. It also warns that aggregating distinct water domains “may be problematic” (a caution the SSI composite’s limiting-domain co-headline, D31, partly answers), and flags that most such metrics lack validation testing — water_ssi is a modelled ratio, not a field-validated index. LIT_065

  • The water self-sufficiency ratio — the model’s water_ssi metric, formalised. The foundational measure is Qlr/Qtd — water sourced locally (recycled wastewater, harvested rainwater, local desalination) ÷ total demand — and it is explicitly boundary-dependent (“depends on the definition of the area or system boundaries”), so a building-scale score and a community-scale score are not comparable; NI must state the community boundary. Observed real-world ratios span 15–80% (25% from household rainwater in Stenløse, Denmark → citywide desal/reclamation in Singapore). Energy requirements “vary by more than a factor of ten amongst the alternative techniques” — the methodological justification for the D28 cascade’s self-sufficiency-order ranking (rainwater → bore → mains → desalination), which is energetically as well as economically ordered. LIT_063

  • Decentralized community-scale water systems (rainwater harvesting, greywater recycling): “can reduce the demand for potable water and eliminate the need for additional treatment and pumping associated with centralized water systems” — 84-paper EWF nexus synthesis validation. LIT_007

  • Centralized water systems inefficiency: approximately 83% of treated water used for non-potable purposes — systemic over-treatment that decentralized alternatives structurally avoid by matching treatment level to end use. LIT_007

  • Potable-treatment CAPITAL. Taumata Arowai permits point-of-entry (end-point) UV + cartridge treatment at each building for small rural supplies (one building <=500 people, or up to 3 buildings <=100), as an alternative to a central plant URL_041. Per-dwelling POE unit from ~1,200 ex-GST equipment (entry) upward, plus install [[url_042_uv-water-systems-poe-price|URL_042]]. The central-plant scale (~270k/plant) is CR_050; use POE for a small community.

  • Livestock water demand + sustainable-take gate. Dairy ~120 L/cow/day (drinking + shed washdown), beef 45, sheep ~3, Horizons RC stock-water guideline OT_225, previously absent from the water demand (asymmetric with the modelled shed electricity). Sustainable-take gate for a credited bore/stream = min(consented take, MALF share for streams / aquifer allocation for bores) from held sources (OT_100 / OT_160 / REG_018).

  • Co-designing decentralized water systems with climate adaptation produces more water and reduces overall costs while lowering energy consumption in centralized systems — water and energy decentralization are mutually reinforcing. LIT_007

  • Hybrid RWHS+GWRS achieves 42.5% potable water savings (131 m³/year) at household scale (4 persons, 203 L/capita/day, 1053 mm/year rainfall); RWHS alone covers 22.8%, GWRS from showers alone covers 19.6%; WTP demand reduced 42.4%, WWTP discharge reduced 20%. LIT_008

  • LCA comparison (13 midpoint + 3 endpoint ReCiPe categories): HS outperforms centralized system in 12/13 midpoint and all 3 endpoint categories; climate change HS = 1.99 kg CO₂ eq./m³ vs CS = 2.44; water depletion HS = 3.32 m³/m³ vs CS = 4.68. Ozone depletion is the sole category where HS is worse, driven by PVC components (>95% of this impact). LIT_008

  • Operational phase dominates RWHS+GWRS environmental impact (>85% of impact in 12/13 categories); total HS pumping energy = 20.55 kWh/year (0.157 kWh/m³) — design optimization should target operational energy efficiency, not embodied material minimization. LIT_008

  • Marinoski & Ghisi (2018): LCA + economic feasibility of household rainwater harvesting (toilet flushing) in a Brazilian low-income house — a 4 m³ tank substituted 27.71% of potable demand at ~1,595 mm/yr. The storage tank dominates embodied energy/CO2: glass-fibre-reinforced plastic was environmentally best while reinforced concrete was cheapest with the only viable payback (14.5 yr vs 25.3/32.7); critically, every RWHS option carried more embodied energy and CO2 than the no-system baseline, so the net environmental benefit depends on lifetime operational water savings. Complements the LIT_008 hybrid RWHS+GWRS LCA. LIT_051

  • Greywater is approximately 75–80% of domestic wastewater (potentially 100% where dry latrines are used) — greywater separation and reuse addresses the dominant fraction of residential waste water and is the highest-volume decentralised water recovery opportunity. LIT_017

  • Bush/garden irrigation is the only greywater reuse application accepted across all treatment conditions regardless of context (Likert 3.54–3.83 across three treatment levels, rural Palestine n=300); crop irrigation unlocked after centralized treatment (3.62); direct-contact applications (drinking, aquifer recharge, aquaculture) consistently rejected — social acceptance profile should be factored into community greywater system design. LIT_017

  • Centralized community-scale greywater treatment commands significantly higher public confidence than household-level home treatment — community-scale infrastructure is both more trusted and more technically reliable than distributed household solutions for greywater reuse. LIT_017

  • Social acceptance of greywater reuse is largely independent of income, family size, and water bills — it is attitudinal and culturally mediated; public education campaigns are the primary lever for expanding acceptance of less familiar reuse applications. LIT_017

  • Living machine (John Todd concept): ecologically-based wastewater treatment built within a greenhouse; uses community’s own waste to produce clean water for reuse and nutrients for local green space — closes the water and waste loops simultaneously at community scale; central courtyard programme element in eco-cell design. LIT_018

  • Rooftop + impervious surface rainwater collection → basement storage → multi-use (human consumption, irrigation, toilet flushing, cleaning): proposed system for 820-person Auckland community targeting 180,000 L/day locally sourced; waste reduction target 96.77→4.00 t/yr via circular urban metabolism. LIT_018

  • On-site water technology prevalence (60 European ecovillages, N=38 water-seeking): water well 68%, rainwater collection 58%, wastewater reuse 37%, water retention 35%, surface water (springs/streams) ~30%, water purification ~28% — well + rainwater collection is the most common decentralised water supply combination; only 24% remain connected to the mains supply network. LIT_020

  • Complete water SS is the most achievable full-SS milestone: 69% of water-seeking ecovillages already at 100% water SS; 79% plan to achieve it — water independence is demonstrated at scale across European ecovillages; land area is the only significant predictor (Spearman r=0.561*, p=0.046). LIT_020

  • MELiSSA waste compartment (C1): thermophilic anaerobic biodegradation achieves >90% organic waste degradation efficiency; the six essential elements (C, H, N, O, P, S) are tracked and recycled at steady state — proof-of-concept that complete biological closure of the water and waste loop is technically feasible. Space context; relevance is conceptual. LIT_019

Multi-domain SS quantification — water and nutrient loops (Knivsta, Sweden)

  • Freshwater fully achievable: rainwater from rooftops (14%) + stormwater from hard surfaces (16%) + graywater recycling (71%) = 100%+ freshwater SS in all three density cases; graywater recycling alone contributes 71% in all cases regardless of density. LIT_022
  • Nutrient recovery nearly complete and density-independent: 78% of nitrogen recoverable (ammonium sulfate 69%, struvite 2%, digestate 7%) and 98% of phosphorus (struvite 68%, digestate 30%) — both figures consistent across multifamily and single-family cases because recovery potential scales with per-capita wastewater volume. LIT_022
  • Graywater management via nature-based solutions is not a binding constraint: NBS green area requirement is 3,502% oversubscribed in Case 1 (multifamily) and 46,727% in Case 3 (low-density) — available green space vastly exceeds what is needed for biological graywater treatment in all tested configurations. LIT_022

NZ community water and waste (Wellington)

  • NZ community design: water catchment + greywater recycling achieves 100% on-site water supply in Paremata design; greywater system identified as highest-failure-risk component across 6 NZ cohousing field trip sites — occupant maintenance attention is a design requirement. OT_018

Earthsong founder water & wastewater account (INT_006, NZ — first primary lived dual-reticulation case)

  • Dual reticulation in practice: all roof water is collected to tanks and reticulated to houses for non-potable use, with city mains supplying drinking water — and the potable split is regulation-driven, because collecting rainwater for more than one household makes it a public-health (rather than private-health) issue with a heavier treatment regime. Greater water self-sufficiency was wanted but dense-urban land limits tank volume (4–5× more would be needed). Interview VI [INT_006]
  • Operational reality: tanks run dry several times each summer, at which point the tank monitor opens taps to bring city water down the line — the city connection is what makes the modestly-sized tank design workable. A grounded NZ counterpoint to the design-figure “100% on-site water” benchmarks above. Interview VI [INT_006]
  • On-site wastewater treatment was engineered and desired but Watercare refused consent; the community chose not to fight it. The three council-sewer connection points were sited close to the planned on-site treatment locations, deliberately leaving a future conversion option — though full site utilisation now means any retrofit would need a high-tech system not requiring a natural treatment area. A concrete NZ regulatory barrier to decentralised wastewater. Interview VI [INT_006]

Slow-water structures & circular heat (INT_007, practitioner)

  • Beaver-dam analogues (low leaky weirs of rock/mud/wood) slow and filter water on a farm: sediment and nutrients settle on the upstream side, the water table rises, streams stay wet longer, water cools, and spawning/insect habitat forms — a low-cost decentralised water-retention and nutrient-capture technique relevant to drought/flood resilience. NZ catchment applicability pending (RT_195). Interview VII [INT_007]
  • Compost-pile heat recovery (Jean Pain method): pipes laid under a large compost pile capture the heat of decomposition and distribute it to houses — a circular community-heat loop turning an organic-waste stream into space/water heating. NZ feasibility pending (RT_198). Interview VII [INT_007]

NZ residential water demand (BRANZ SR469 — the model’s person_water_demand)

  • First national-scope NZ residential water-use measurement (66 households, 10-second metering + survey + appliance inventory): median 159 L/person/day in winter, 231 in summer; the report recommends the median over the mean (213/292 L/p/d) because a minority of heavy users skews the average. Resolves the ③ person_water_demand_l_day gap, replacing the overseas 203 L/capita/day proxy. OT_036
  • Median household demand ~435 L/day (winter) / 504 L/day (summer) — the figure the rainwater supply (CR_016 yield, OT_030 rainfall) is sized against. With ~65% of household need meetable from roof (CR_016) and <10% of NZ homes currently having any rain tank, the rainwater intervention has large headroom. OT_036
  • MBIE residential water-efficiency target = 75 L/person/day (Watercare–Fletcher “1.5-degree home” pilot) — the natural high-efficiency design scenario for a water-conscious community; ~28% of homes have outdoor sprinkler/irrigation systems, a large and sheddable summer load. OT_036

Rainwater harvesting (NZ cost & yield)

  • Live NZ HDPE round-tank pricing ~NZD 110–135/m³ of storage for ≥15,000 L (excl. GST); 10,000 L ~2,100–2,600. A full household system runs ~3,500–6,000 (garden/non-potable) to 8,000–15,000 (sole potable with UV). Cost per m² catchment ~50–90/m² is a weak derived metric — storage volume is the real cost driver. CR_016
  • Roof collection efficiency 75–90% (use 0.80 — matches the model runoff coefficient); ~65% of household water needs meetable from roof; 35,000 L is the largest ground-supported tank with no building consent. CR_016
  • Earthsong built cost (primary, audited). The six communal rainwater tanks (~190,000 L; ~32 dwellings) cost NZ101,110.50 incl GST** over 2002–07 — a fully-installed **~532/m³ including burial, pumps, dual-reticulation and electrical, i.e. ~4× the bare HDPE shell price (CR_016 120/m³). The full water-sensitive-design package (tanks + swales + raingardens + porous paving + landscaping) was **663,296 incl GST**, 50%-funded by an Infrastructure Auckland grant (93,471). The model's water-capex line should use an *installed* /m³, not the tank-shell price. ⚠ 2002–07 NZD — apply CPI (×1.6) to 2026. OT_078
  • Earthsong measured water PERFORMANCE (primary, 2005–08 — the model-validation counterpart to the OT_078 costs). Four years of metered dual-reticulation data: average use ~174 L/p/d (range 144–193) = 58–80% of the Auckland region (~240–247) and 72–96% of Waitakere (~180–214). Crucially, on-site rainwater met only ~50% of needs, below the 70% design target — tank volume is land-limited (192,000 L across 32 homes ≈ 6,000 L/home still leaves ~half the supply on mains in Auckland’s climate). Validates three model assumptions at once: person_water_demand ~175–195 L/p/d (Earthsong ~174 despite being water-conscious), the rainwater-supply cap (“runs dry every summer”, INT_006), and the tank-sizing → water_ssi seasonal balance (with RD_023/OT_030). The dual-reticulation split (drinking on mains; hot water/shower/bath/WC/laundry/outside on tank) sets the non-potable fraction rainwater can offset. OT_092

Earthsong measured WASTE reduction (primary, WCC audit 2010 — the D03 circular/waste benchmark)

  • On-site composting + source-sorting cut Earthsong’s landfill refuse to ~2.80–3.65 kg/household vs the Waitakere average 9.61 kg/household (~a third; WasteNot WAP 2009). The mechanism, not the bag count, is the lesson: only 24.4% of Earthsong’s refuse was still divertable (organic 14.3% + paper 9.3% + recycling 0.9%) vs 73% for the city (organic 51% + paper 10% + recycling 12%) — because organics are composted on-site. A real NZ community waste-reduction benchmark for the circular lever: composting + sorting drives the reduction. OT_094
  • Design & consent layer (BRANZ Bulletin 664, the primary): the runoff coefficient is corroborated — BRANZ sizing assumes only 10–20% collection loss (≈0.80–0.90), confirming 0.8 as the conservative-correct value. The consent-free tank schedule is a hard sizing constraint: ≤35,000 L ground-supported needs no building consent, falling to 16,000 L (≤0.25 m), 8,000 (≤0.5 m), 4,000 (≤1 m), 2,000 (≤2 m), 1,000 L (≤3 m) — community storage above this triggers a consent. OT_039
  • Potable vs non-potable (regulatory): potable rainwater must meet AS/NZS 4020:2018 + (recommended) NZ Drinking Water Standards 2005/2018, with a treatment train of leaf strainer + first-flush diverter + sediment filter + UV/chlorine; non-potable must be lilac-labelled (AS/NZS 3500.1, NZS 5807, G12/AS1) with backflow prevention. Reticulating roof water to more than one household can cross into “public supply” and a heavier treatment regime — the regulation-driven reason Earthsong keeps drinking water on mains. See the technology page rainwater_harvesting. OT_039 Interview VI [INT_006]

Greywater recycling (NZ demand-reduction, BRANZ Bulletin 665)

  • Greywater (baths, showers, basins, sometimes laundry — not kitchen/dishwasher) is produced at 100–200 L/day per household ≈ 20–45% of household water demand (vs ~435–504 L/day, OT_036) — a large, rain-independent year-round reuse stream. Untreated → subsurface irrigation (use within 24 h); treated (filter + disinfect) → toilet flushing; never potable. The demand-side companion to rainwater supply; see the tech page greywater_recycling. OT_040
  • Regulatory (heavier than rainwater): greywater systems need a building consent as an Alternative Solution (no Acceptable Solution exists) plus possible resource consent for land discharge; council policies vary and no single NZ law covers it end-to-end (AS/NZS 3500.2:2021; non-potable labelling per AS/NZS 3500.1). A real consent barrier for a community design — Earthsong’s on-site wastewater reuse was refused consent by Watercare. OT_040 Interview VI [INT_006]
  • Structural benchmark: greywater recycling alone supplied ~71% of community freshwater self-sufficiency in the Gullberg multi-domain study — the single largest water-loop contributor (Swedish context). LIT_022

Composting (waterless) toilets — NZ regulatory + performance basis (OT_124) + price/cert anchor (URL_026) + availability marker (URL_009)

  • Composting toilets (waterless sanitation + nutrient recovery — avoid reticulated blackwater, save water, close the nutrient loop) are commercially available in NZ via Clivus Multrum / Waterless Composting Toilets NZ (WCTNZ), in split batch (two rotating chambers) and continuous configurations with a urine-diversion option. ⚠ Vendor marketing page only — no capacity, water-savings, compost-yield, cost or AS/NZS 1546.2 compliance data; the inputs needed to size/cost a deployment are a gap (RT_223). Technology/supplier pointer for the D03 sanitation theme, not a usable input. URL_009
  • The authoritative NZ regulatory + performance basis the URL_009 vendor page lacked (ESR / Ministry of Health scoping study, FW 24031). Composting toilets save 15–28% of indoor household water use vs flush (report attributes the figure to Salmon et al 2004) — a demand-side lever for the D03 water balance alongside OT_036. The AS/NZS 1546.2:2008 compliance gate: the composted end-product must be moisture < 75% by weight, total faecal coliforms < 200 MPN/g dry weight, Salmonella not detected in 4 g dry weight, then buried in soil for 6–12 months under ≥100 mm cover, access restricted, no contact with consumable plants or surface water (or removed by an authorised contractor). In NZ’s temperate climate thermophilic temperatures (>50°C) are rarely sustained, so the product must be treated as hazardous until buried — a management-intensive waterless-sanitation option, not set-and-forget. Pairs with the on-site-wastewater regulatory stack in REG_013. OT_124
  • ⚠ Cost + per-model sizing still a gap; consenting is a live permitting risk. The report gives no composting-toilet installed cost — only a 15,000–40,000 conventional on-site-wastewater (septic) comparator that composting toilets are said to undercut (pers comm Dakers & Ambury), which corroborates CR_048’s septic band but is not a composting-toilet CapEx. The only capacity datum is coarse — > 4 people ⇒ daily emptying into a secondary chamber (no per-model persons/uses·day, compost yield or removal interval). NZ has no consistent consenting pathway (discharge-consent vs permitted-activity split; very few marketed systems document AS/NZS 1546.2 compliance) — a real feasibility flag alongside CR_046 and REG_012. Closes the water-saving + regulatory legs of RT_223; per-model specs + installed cost stay open — equipment price band now anchored by URL_026; numeric capacity/yield/interval + installed cost still open. OT_124
  • The first hard NZD price anchor + product-level AS/NZS 1546.2:2008 certification (WCTNZ Clivus Multrum storefront). Four Clivus Multrum composting-toilet SYSTEM models are listed at 5,429.57 (CM HP, single-household) / 9,363.23 (CM8) / 13,350.93 (CM14, large family) / 19,501.54 (CM40, high-use commercial), all ex GST — the composting-toilet EQUIPMENT-price band OT_124 lacked (it gave only a $15–40k conventional septic comparator, not a composting-toilet cost). ⚠ Ex-GST, equipment/package only — installed cost (underfloor-chamber install, plumbing, ventilation, labour, consent) is additional and unquantified. Selected systems are certified against AS/NZS 1546.2:2008 and have been used in council-consented NZ projects — so at least one NZ supplier clears the compliance-documentation gate OT_124 and CR_046 flagged as the live feasibility risk. Capacity is qualitative only (no persons/uses·day) → numeric sizing + installed cost stay open on RT_223. URL_026

Anaerobic digestion / biogas — viability & sanitation framing (CR_039)

  • Biogas is Conditional for NZ remote communities and best framed as sanitation + nutrient recovery, not energy: AD digesters sour below ~20 °C internal — about half the NZ year — so an unheated household digester is not a reliable year-round energy source anywhere in mainland NZ; community/farm scale works only with a concentrated year-round feedstock (dairy effluent, piggery, aggregated food-waste/blackwater) + a heated digester. CR_039
  • Even where viable, output is modest — a NZ dairy case covered farm hot-water only; energy-led economics need ~500 cows (NZ average herd ~450 is borderline). The stronger justification is digestate biofertiliser + waste stabilisation, closing the nutrient loop (cf. the Gullberg digestate recovery figures above), with biogas heat a co-benefit. The NZ dairy output figures are now verified-primary (LIT_086): a 410-cow System-5 farm produced 558 MJ/day (solids) + 176–861 MJ/day (liquid), covering the farm’s ~221 MJ/day water-heating load with a tankless heater — heat only, not electricity (capex still unsourced). See the tech page anaerobic_digestion. LIT_086 CR_039
  • Regulatory & digestate status (CR_041, resolves RT_270 + RT_271): community/on-farm digesters fall under four NZ pillars — WorkSafe H₂S limits (WES-TWA 5 ppm / STEL 10 ppm), Gas (Safety & Measurement) Regs 2010 + AS/NZS 5601.1, Building Act consent, and RMA discharge consent. Digestate is a high-availability N biofertiliser (82–90% plant-ready ammonium) that meets the ACVM-Act fertiliser definition (ACVM-exempt if BANZ-accredited; else a biosolid) — and a community applying its own digestate on its own land falls under regional-plan rules, not commercial accreditation. OT_080 CR_041
  • International corroboration of the community-scale AD verdict + waste-heat water recycling (Malawi, Robin & Ehimen 2024). A rural-Malawi fixed-dome AD techno-economic study independently reaches this page’s conclusion — cow-dung-alone / household-only unviable, co-digestion in a large shared reactor the only positive-NPV path (best case NPV +8,962.58, LCOE 0.06/kWh), digestate a saleable NPK-fertiliser co-product. It also frames a closed water loop: CHP waste heat recycles 50–70% of process water (pump) and the digester needs only 2.7–11 m³ water/yr, presented as a co-benefit in water-scarce areas — the water↔waste↔energy nexus this domain tracks. ⚠ Malawi 2023 USD; corroborates but does not re-parameterise anaerobic_digestion. LIT_076
  • Cold-climate seasonality + fertiliser-first framing — primary field study (Bozeman MT, Ebel et al. 2025). The retrievable primary behind CR_039’s energy-vs-nutrient framing, and independent corroboration of its cold-climate seasonality (CR_039’s own “≈6 months/yr” figure traces to Castaño et al. 2014, not this study): a 12-household case study in a cool-continental US town found household-scale AD “not functional for over 6 months of the year due to cold temperatures” (ambient 15–21 °C vs mesophilic optimum 35 °C; incomplete digestion, final pH 5.7; winter disassembly to stop the digestate freezing), and confirms the energy-vs-nutrient verdict directly — the digesters were run for digestate biofertiliser, methane was not a goal, and half the gas-capable units produced no usable biogas, yet 87% of participants would still recommend the technology. Independent-geography support for the anaerobic_digestion “household Out (seasonal) / community Conditional” verdict. ⚠ Montana context; qualitative case study (n = 12 households) — transferable pattern, not NZ figures. LIT_087

Nelson–Tasman water-resource climatology (Macara 2016 — pilot ② rainfall)

  • Annual rainfall normal (1981–2010): Nelson 959 mm (driest of the region), Motueka 1,341, Takaka 2,012; Tasman Mountains >6,000 mm. Fairly even through the year, Feb–Mar driest. Fills the pilot ② rainfall_mm (rainwater catchment yield); national 16-region rainfall remains RT_142. OT_030
  • Dry-spell + irrigation exposure: dry spells (≥15 days <1 mm/day) at Nelson average one every 4 months, mean 20 / max 40 days, most frequent in summer; mean annual soil-moisture deficit Nelson 317 mm (PET 901 mm) — summer irrigation is necessary, and rainwater storage must buffer multi-week dry periods coinciding with peak irrigation demand. OT_030

Water-supply backstops — cost & energy (CR_032, the D22 cascade fallbacks)

  • Borehole (local backstop): drilling+casing ~NZD 12,000 (range 8k–20k) + installed pump/pressure system ~NZD 4,500; pump energy is physics-governed kWh/m³ ≈ 0.00272 × head_m ÷ eff ≈ 0.25 kWh/m³ at 50 m head (an order of magnitude below desalination). Ceiling is regulatory: regional plans set a permitted-take limit of 5–50 m³/day (region-specific, not a national ~20) above which a water-take consent is required — and good aquifers (Canterbury, Heretaunga, Waimea) are often over-allocated. See borehole. CR_032
  • Mains connection (import backstop): physical connection ~NZD 3,500 + a development/growth charge (Auckland Watercare Infrastructure Growth Charge NZD 21,175 incl GST, water+wastewater, 1 Jul 2024) + pipe extension ~NZD 250–400/m where the main is distant (1 km → NZD 250k–400k); volumetric tariff NZD 2.30–2.46/m³ (Watercare) where metered. Consuming mains water is an import → reduces water_ssi (water analogue of grid electricity). Many NZ councils are unmetered/rates-funded, so the volumetric term often doesn’t apply. See mains_connection. CR_032
  • Desalination (coastal local backstop, energy nexus): the most energy-expensive backstop — seawater RO ~4 kWh/m³ (band 3.5–5), brackish RO ~1 kWh/m³ — capex ~USD 2,500 ≈ NZD 4,200 per m³/day (international, small-scale premium; no NZ community-scale plant exists). Brine disposal (<50% recovery) needs an RMA coastal-discharge consent — often the binding constraint. NZ desal is feasibility-stage/island/emergency only (Waiheke feasibility study). See desalination. CR_032

Nelson metered water tariff — the 2nd council anchor for the D22 mains-import backstop (REG_030, primary, verified)

  • A second metered NZ council, with a two-part tariff CR_032’s single Watercare anchor missed. Nelson City Council’s 2025/26 rates resolution (statutory, LG(Rating)Act 2002) sets a two-part water tariff: a fixed Water Annual Charge NZD 273.42 per metered connection (s16) plus a volumetric rate tiered by annual usage — NZD 2.764/m³ up to 10,000 m³/yr (the residential tier), 2.349 (10,001–100,000), 1.935 (>100,000), and a summer-irrigation rate 2.570/m³ over 10,000 m³/yr — all GST-inclusive. Wastewater is a separate flat targeted rate NZD 708.57/SUIP (residential, connected; commercial 177.14/SUIP + trade waste). So the mains_connection opex cell should be fixed_annual + volumetric × m³, not volumetric-only: Nelson’s residential volumetric (2.764) sits above Watercare’s 2.46/m³, widening the national metered range to ~NZD 2.46–2.76/m³ (⚠ GST-basis-dependent) with a ~NZD 273/yr fixed part. Nelson is fully metered (per-connection charge only “where a water meter is installed”; ~⅔ of water revenue raised volumetrically) — a second counter-example to CR_032’s “many councils are unmetered”. Bills water and wastewater as separate rates → the water-only/wastewater split RT_261 wanted (vs Watercare’s combined IGC). Advances RT_261 (Nelson = 1 of 4 councils); Tasman/Kāpiti/Christchurch still open. REG_030

On-site wastewater (septic/AWTS) + greywater installed costs (CR_048 — fills the D03 sanitation cost cells)

  • Septic: conventional tank + drain field ~NZD 15k (10–20k) per household; but councils now require advanced/AWTS for new builds → NZD 20–30k the realistic band (secondary+UV 25–40k). Resolves RT_278. Pairs with the CR_046 wastewater-consent gate (RMA s15; Canterbury Rule 5.8 ≤2,000 L/day + ≥4 ha). CR_048
  • Greywater: WCTNZ equipment ex-GST NZD 1,130 (gravity diverter) → 1,913 (treatment); installed ~3–5k diversion / 5–8k+ treatment. Year-round reusable fraction ~25–35% (estimate) — brackets the engine’s interim GREYWATER_FRAC = 0.30; installed-total + reuse % stay soft (RT_211 partial). First NZ cost data for greywater_recycling. CR_048

Off-grid infrastructure cost reference (CR_050 — AI-compiled synthesis, verified-source-only)

  • Small surface-water treatment capex: no single NZ /m³·day benchmark; triangulated ~**2,000–8,000/m³·day** → a 50-dwelling / ~10 m³·day scheme ≈ **150,000–400,000** (treatment plant only). Bracketed by the FILTEC CIP rural modular programme (>27M / 100+ plants ≈ ~270k/plant, vendor page → RT_321) and Motueka WTP ~3.5M (context only). ⚠ RT_321 primary now retrieved (URL_027): the FILTEC programme page confirms the ≈120-plant / 25–100 m³ modular scale but is UNPRICED — the “27M / 270k” is NOT on the vendor page, even though CR_050 §1 sources the bracket to it (“FILTEC programme page [^1]”), so the ~270k/plant bracket is unverified and the treatment-capex residual stays OPEN (the 27M’s true origin is unestablished). Gives the inert stream_abstraction lever (RT_310) its first cost band. data_quality medium. CR_050 URL_027
  • **Water-take consent (non-notified stream take, all-in) ~15,000–35,000** (Auckland deposit 7,000 + Marlborough base ~7,218 [council schedules] + applicant AEE/planner 10–30k [MfE CBA]) — independently corroborates CR_045’s $25–35k and the interim water_take_consent_capex ~30k. Primaries → RT_296 + RT_320. CR_050
  • Community water RETICULATION (fills the AF-16 gap — the costed reticulation line is electrical, CR_027; water distribution was uncosted): triangulated ~5,000–20,000/dwelling** full scheme; 100 mm HDPE main ~**1,600–2,500/m installed [QLDC/Opus DBC → RT_317]; national-assessment-derived ~**3,300–5,000/connection** (~23bn network value) [tandfonline 2025 → RT_316]. A NEW water-reticulation cost line, distinct from the electrical one. data_quality medium. CR_050
  • Greywater treated full-reuse band: diverter 500–1,500; pumped GWDD ~1,800–3,000 (unit 1,281 excl GST = **the same WCTNZ figure as CR_048**); **full treated in-house reuse 8,000–18,000 installed** — extends CR_048 with the treated upper band; the engine’s interim greywater_capex_per_dwelling $4,000 is diverter-class, not treated. Australian pricing → medium. CR_050
  • Asset service lives (feed the AF-17 reserve params.ASSET_LIFE, RT_312): DH pre-insulated mains 30-yr min (EN 253:2019) / 50-yr planning [→ RT_318] (engine 40 ✓ mid-range); concrete septic 30–40yr+ / Waimate AMP 80-yr base life [→ RT_319] (engine wastewater 25 ✓ conservative); AWTS motor/pump 5–10yr; rainwater poly tanks 10–20yr and electric HW cylinders 10–15yr rest on trade blogs (Tier-3) → flags the engine’s rainwater 30 as OPTIMISTIC if poly dominates, dhw 15 = top of range; RT_312 stays open for an IPWEA/NAMS or BRANZ component-life table. CR_050

Waimate DC Wastewater AMP 2021–31 — CORRECTS the CR_050 “80-yr concrete septic” reading (OT_110, primary NZ council document, verified)

  • The buried-pipe base lives (Table 3-3) are earthenware 80 / PVC 100 / MDPE 100 / reinforced-concrete 60 yr — the only 80-yr figure is earthenware pipe, not “concrete septic” (reinforced-concrete pipe is 60 yr); a second, unrelated 80-yr life is a single building (§3.8). So the CR_050 asset-lives bullet above (“Waimate AMP 80-yr base life”, → RT_319) conflates the wrong material with the wrong asset class: this AMP is a reticulated urban wastewater network (39.2 km mains + oxidation-pond WWTP, $25.1m 2020 optimised replacement value), not septic infrastructure. Read verbatim from the valuation tables → supersedes the CR_050 reading. OT_110
  • What it legitimately anchors: buried reticulation is long-lived (60–100 yr, straight-line, FRS3/NZ IAS 16), confirming params.ASSET_LIFE wastewater 25 yr is conservative for reticulation — but the AMP states no on-site septic/AWTS tank life (its only septic tanks are the private St Andrews system, life unstated), so the tank-life NI actually needs stays open (RT_312). RT_319 resolved → OT_110. OT_110
  • The BRANZ component-life reference RT_312 named is now in-corpus — but it anchors the FABRIC lines only (BRANZ SR351). OT_158 (BRANZ Study Report SR351, Dowdell et al. 2016) is the BRANZ whole-building whole-of-life datasheet report the AF-17 reserve audit called for (“IPWEA/NAMS or BRANZ component-life table”). It anchors the reserve’s building-fabric lines: a NZ office required service life 60 yr (Building Code B2.3.1(a) 50-yr durability floor; Green Star 60 yr), and — as Module B4 replacement worked examples — bitumen-sheet roofing 22 yr (min 20, max 25) and a concrete component 100 yr. This places the engine’s catchment-structures 30 yr assumption mid-range but roofing-material-dependent — a membrane/bituminous roof (22 yr) makes 30 optimistic, long-run metal or concrete (up to 100 yr) makes it conservative. ⚠ But SR351 is office-fabric-scoped (Table 6’s only “7 Services” entry is CBI 5323 suspended ceiling with services), so it does not carry the mechanical/services lives the reserve mostly comprises — DHW 15, AWTS/wastewater 25, poly tanks + plumbing 30, DH mains 40, V2H 15 — leaving the CR_050 Tier-3 conflicts (poly tanks 10–20 yr; HW cylinders 10–15 yr) neither confirmed nor refuted. And the actual per-component life table is an external Excel (branz.co.nz/buildingLCA, by CBI code → RT_384), not in the report. So RT_312 is advanced (fabric side anchored) but stays open for the services lines (IPWEA/NAMS schedule or the B4 Excel). OT_158

Ladies Mile DBE civil-rate card — CORRECTS the CR_050 “1,600–2,500/m watermain" reticulation /m (OT_113, signed NZTA-accepted primary, verified)

  • The CR_050 reticulation $/m is a mis-attribution — struck and corrected. Reading the QLDC/Opus Ladies Mile Detailed Business Case Estimate (June 2018, accepted by NZTA) verbatim, the “100 mm HDPE main ~1,600–2,500/m installed" CR_050 recorded (AF-16 / RT_313, bullet above) is wrong on three counts: there is **no 100 mm watermain** in the estimate (smallest pressure watermain **DN315**; smallest pressure pipe of any kind **DN160**); the **1,600 (Opus) / 2,500 (WTP)** figures are the **1050 mm RCRRJ *stormwater*** pipe rate (p.5), not a watermain; and the real watermain "supply, weld and lay … PE100 PN12.5 (incl. all valves and fittings)" rate is **200–350/m** (DN315–355), all-in ~614/m base / ~798/m P50 over 3340 m. The CR_050 1,600–2,500/m band must be read as 200–350/m supply+lay (all-in ~$600–800/m) — the “right document, wrong line” failure mode (feedback_cr_verified_source_only); annotated on the CR_050 page; the model-side correction is flagged. OT_113
  • A diameter-resolved supply-and-lay card for the D22 water-cascade mains. PE100 pressure main 200–360/m** (DN160–DN355); gravity PVC-U SN8 **300/m (225 mm) → 650/m (600 mm) → 800/m (750 mm); RCRRJ stormwater 950/m (525 mm) / 1,600–2,500/m (1050 mm); NZTA-F2 110 mm subsoil drain **60/m** — complementing [[cr_032_nz-water-backstop-costs-2026|CR_032]]'s ~250–400/m mains-extension figure with a diameter-resolved basis. ⚠ Ladies Mile is a large trunk scheme (DN315–355 mains, 2×1000 m³ reservoirs) → an upper bound; a remote community’s cheaper 100–150 mm distribution main is not priced here, so the small-diameter community rate stays open (RT_369). Also 2018 base, ex-GST, ex-escalation → apply CPI/CGPI to 2026 (escalation factor = RT_368). OT_113
  • CGPI water-&-sewerage escalation deflator — de-dates OT_113’s June-2018 three-waters rates (RD_032, Stats NZ, verified). OT_113’s watermain/stormwater $/m rates are a June-2018, ex-escalation base; the correct escalator is the Stats NZ CGPI systems for water and sewerage sub-series (CEPQ.S611031B, base Sep-2022=1000) = 1100 at Mar-2026, +4.0% YoY (+1.0% QoQ) — three-waters civil has run hotter than the all-groups CGPI (+1.2% YoY) and the whole civil-construction group (+3.1% YoY). ⚠ Release covers Mar-2024→Mar-2026 only; the 2018→2026 factor needs the Jun-2018 value from Infoshare — RT_368 open. RD_032

MfE/Beca NES-DW CBA case studies — the govt primary behind CR_050’s $10–30k applicant consent cost (OT_111, verified)

  • **A low-complexity RMA resource-consent applicant cost of 10,000–30,000 plus a separate 30,000 risk-assessment line** (Beca-for-MfE NES-DW CBA case studies, Table 3-1, 2022 NZD) — the government primary behind CR_050's "10–30k applicant AEE/planner [MfE CBA]” bullet above. It independently brackets the engine’s interim water_take_consent_capex (~25–30k) from a govt source and converges with CR_045 (25–35k) and [[cr_052_nz-bore-consent-cost-legume-luc-yield|CR_052]] (12–30k all-in) → the consent-cost band is now corroborated from a primary. Medium/high bands 30–50k / 50–200k; council processing 3–16k; monitoring 2–20k/yr. ⚠ These are generic per-consent RMA applicant costs (bore/agrichemical/discharge consents in a drinking-water source zone), not s14 water-take-specific — it verifies the cost driver (consultant AEE/planner time per consent), not a water-take price, so RT_297 (a real water-take quote) stays open. OT_111
  • Aerated (AWTS) on-site wastewater install 15,000–20,000 (§4.3.2; also Table 4-2 “Mitigation”) — a government datapoint corroborating CR_048’s NZD 20–30k advanced-treatment band from the bottom (this is the aerated-upgrade component; CR_048’s is the full installed system). The report frames mandatory AWTS as a cost burden that “can also become an incentive for the reticulation of sewage in small communities” — a real NZ statement of the D03 community-reticulation tipping point. OT_111

FILTEC Rural Drinking Water Partnership programme page — CONFIRMS the CR_050 FILTEC plant SCALE but shows it is UNPRICED (URL_027, vendor/programme primary, medium)

  • The FILTEC modular plant CR_050 cited for ”~270k/plant" is real at the modelled scale — but the page carries NO cost.** Retrieved as the RT_321 primary behind CR_050's surface-water treatment capex band, the FILTEC × Crown Infrastructure Partners programme page confirms ≈**120 standardised modular treatment plants**, **systems "range in volume from 25 to 100 cubic metres"** (⚠ page states no time basis; the AquaSAFE spec CR_053 records is 25–100 m³/**day**), workshop-fabricated (Mount Wellington), site-installed, with a **≤5-year maintenance + operator-training** wrap, validated by a **year-long six-marae North Island pilot** (DWSNZ-compliance-driven; CIP the implementation agency). This is the same AquaSAFE-class unit [[cr_053_nz-surface-water-scheme-costs|CR_053]] names as its standing residual. ⚠ **The page discloses no per-plant cost, no total, no /m³·day — yet CR_050 §1 sources its “>27M / 100+ plants ≈ ~270k/plant” bracket to this very page (“FILTEC programme page [^1]”). That attribution is therefore unsupported by the page (the dollar figure is not on it); the $27M’s true provenance is not established by the retrieval. Net: firms the existence + scale of the treatment technology, confirms the treatment-capex residual is genuinely OPEN — a real FILTEC/Hydroflux supplier QUOTE is still needed (RT_310/RT_321 residual). Same “right programme, wrong source for the number” pattern as the OT_110 / OT_113 CR_050 corrections above. URL_027

Surface-water reliability in drought (OT_099 — observed, the D34 summer-dry anchor)

  • A real NZ drought takes a river to 0.40–0.92 of its MALF. Five large Hawke’s Bay rivers in the 2019-20 drought: Ngaruroro 0.40, Tukituki 0.47, Mohaka 0.60, Esk 0.68, Wairoa 0.92 (7dALF ÷ long-term 7dMALF). The Wairoa catchment escaped the regional rainfall deficit; excluding it the band is 0.40–0.68. Anchors the engine’s drought_fraction_of_malf = 0.5 (D34 summer-dry gate) — previously assumed, now sourced. ⚠ The analogue is large rivers (mean 5.3–77 m³/s), not community-scale streams (RT_334). OT_099

  • A stream take is the first thing switched off. Councils impose low-flow bans — ceasing consented surface-water extraction once flow drops below the minimum flow — and the bans were in force at the 2019-20 lows. Any design leaning on a stream take needs a dry-year fallback; the take cannot be assumed available exactly when demand peaks. Bounds the currently-inert stream_abstraction lever (RT_310, limitations O2). OT_099

  • The regime that governs any community stream take (OT_100). Limits are set as percentages of naturalised 7-day MALF. For streams with mean flow <5 m³/s (essentially every community-scale stream): 2008 proposed NES defaults = minimum flow 90% of MALF + allocation 30% of MALF; Cawthron’s proposed Otago defaults are tighter (90% minimum flow, 20% allocation). Beca (2008): abstraction >40% of 7-d MALF — or any flow alteration using impoundments — is “a high degree of hydrological alteration”. Ecological risk rises as streams shrink (“the smaller the mean flow, the greater the risk presented by the same flow alteration”). Regulatory frame for the stream_abstraction lever (RT_310). OT_100

  • A third region’s minimum-flow convention (OT_160) — plus a de-minimis threshold. GWRC (Wellington pNRP, 2015) sets the default minimum flow at 90% of 7d naturalised MALF at the point of abstraction — adopting the MfE 2008 proposed-NES rule (90% ≤5 m³/s, 80% above), the same band Otago uses. New here: minimum-flow restrictions may only “become operable” once catchment allocation reaches ≥20% of 7d MALF-N (below that the alteration is within ±8% gauging error) — a de-minimis angle for the currently-inert stream_abstraction lever (RT_310). GWRC gives small streams no extra protection (unlike Horizons’ 95%-of-1d-MALF), and benchmarks on MALF because its return period is ~1.8 years — an ecologically-relevant, frequently-recurring low flow. Appendix 2 catalogues the alternative NZ conventions (Waikato/BoP 90–95% of the 1-in-5-yr Q5; GWRC-historical 60% of the 1-in-20-yr low flow) — the engine’s 90%-of-MALF is mainstream. OT_160

  • Te Mana o te Wai is a ceiling on the self-sufficiency claim (OT_101). The NPS-FM 2020 hierarchy of obligations ranks (1) the health of water bodies and freshwater ecosystems, (2) the health needs of people, and (3) “the ability of people and communities to provide for their social, economic, and cultural well-being” — and applies to all freshwater management. A community’s water take or hydro diversion sits in tier 3. The D22 cascade and the D26 physics gate are necessary conditions, never sufficient ones: a stream-dependent design must never be presented as if consent were a formality. Diversions (not just abstractions) are regulated flow-altering activities. OT_101

Surface-water scheme COST STACK — un-inerts the D28 stream_abstraction lever (CR_053, Perplexity Deep Research synthesis, RT_310 resolved-with-residual)

  • The cost to build + run a community stream take, finally costed as a full stack (~75–300k CapEx / ~10–35k/yr OpEx for 20–100 HH, ~5–30 m³/day, excl. reticulation). Four components: intake (screened weir/gallery) 15–60k**; **pump + rising main + power** **15–50k + 0.5–3k/yr**; **DWSNZ treatment** (5-µm filter + UV ≥40 mJ/cm² + chlorination, ± coagulation — the surface-water floor a >30 m bore avoids) **40–150k (~5–8k/m³·day)** + **1.50–4.00/m³; RMA s14 take consent **3–30k** (up to 200k if notified). This assembles CR_050’s treatment-only “first cost band” (the 5–8k/m³·day here sits in CR_050's ~2–8k/m³·day) into the FULL scheme, giving the inert lever a medium-confidence cost so a riverside site is no longer read flatly water-infeasible. Cost-ordered against the sibling backstops: deep bore cheapest (~20–50k/bore, no filtration — [[ot_090_mpdc-brown-bros-bore-drilling-costs|OT_090]]/[[cr_045_nz-community-water-consent-borehole-costs|CR_045]]), **surface water mid but treatment-heavy** (this source), **mains a step-change** (~180k–2.1M+ IGCs — CR_032). ⚠ Disclosed vs estimate: the consent bands = OT_111 (Beca/MfE Table 3-1, verbatim) and the pump base = OT_090 (MPDC Council-AI table), both cross-referenced not re-ingested; but intake (15–60k)** and **treatment (40–150k) are the synthesis’s own engineering estimates (no disclosed NZ small-scheme figure) → carry an explicit estimate flag, firm via a FILTEC/Hydroflux quote (standing RT_321). data_quality medium. CR_053

Community water-take consent + borehole cost scaling (CR_045 — corroborates + extends CR_032, verifies Tier-A params)

  • Consent is unavoidable for a communal supply: RMA s14(3)(b)‘s domestic exemption is per-individual and cannot be stacked, so any multi-dwelling bore/intake needs a water-take consent regardless of volume (Auckland Council guidance) — the engine’s hh≥2 → consent gate, cross-confirmed. Plus Taumata Arowai registration for ≥2 households (DWQAR 2022). CR_045
  • Consent cost NZD 25,000–35,000 typical (non-notified; hydrogeology/AEE-dominated, not council fees 2–7k) — confirms the model’s interim water_take_consent_capex 25k, supports ~30k midpoint. CR_045
  • Borehole drilling primary-verified: Brown Bros/MPDC quote — 285/m mud rotary, 21,440 for a 64 m 100 mm bore (ex-GST); community 150 mm casing +20–30%. Flags the model’s 12k drill-capex as low for community scale. Now filed as the verified primary OT_090 (WRC bore permit $546.25 / 15 m³/day drill-take; >15 m³/day→take consent). Permitted-take 10-council table (5–50 m³/day per property) confirms 30 m³/day national-indicative. CR_045
  • Community bore-consent cost breakdown (CR_052 — advances RT_297, refines CR_045). Itemized consultant cost for a non-notified community water-take AEE: 24–72 hr constant-rate pumping test 3–6k + hydrogeological/drawdown report 4–8k + AEE/application write-up 3–5k = **~10–19k consultant** (excl GST; firms Allegrow/T&T/Hazard); + regional-council fees (1.5–5k deposit, region-varying) → **all-in ~12–18k best / 18–30k typical / 30–60k+ if notified**. Slightly below CR_045’s 25–35k; annual ongoing ~200–500/yr. ⚠ Indicative (fee schedules + industry practice), NOT a real consultant quote → water_take_consent_capex firming still needs a real quote (RT_297 open). CR_052

Waikato RC + ECan water-take consent fee schedules — the council-fee + annual-charge primaries behind CR_045 (REG_025, verified, resolves RT_296)

  • Council fees are a deposit-plus-hours mechanism, not a fixed price — primary-verified. Neither council pre-prices a water-take consent: ECan charges a 5,000 single-consent deposit** (GST-incl) with actual/reasonable costs recovered above it; **Waikato a 1,000 minimum deposit (or ≤50% of the estimate) then staff at 160–220/hr** — which **primary-verifies CR_045's "Waikato hourly 160–220” band exactly and puts ECan’s 5k deposit at the *top* of CR_045's 2–7k non-notified-fee band. The Waikato bore consent (controlled activity) 475 excl = 546.25 incl reconciles OT_090’s WRC bore permit (the gap was GST). ⚠ GST basis differs — ECan incl, Waikato excl → normalise before a cross-council cost cell. Confirms the mechanism behind the council-fee slice of water_take_consent_capex; the dominant hydrogeology/AEE consultant cost is covered by no schedule (RT_297 stays open). REG_025
  • ⚠ Revises CR_045’s annual-charge FLOOR downward — the published floor is ~230/yr, not 300. The annual consent-holder / compliance charges are modest and volume-scaled: ECan 230/water-permit/yr** (GST-incl); **Waikato ≈230/yr for a modest non-farm water take (165 admin + 65 info-gathering, +80 for a farm take, then 48c/m³ by volume). Both floors sit **slightly BELOW CR_045's stated 300 lower bound**, so REG_025 revises CR_045’s annual-charge floor down from 300 to ~230 — a minor correction, not a confirmation of its “low end”. The 1,500 top is volume-driven (48c/m³), not a fixed published number. Keep the model's annual-charge input at the ~230–310/yr low end unless a large-volume take is modelled. REG_025

Regulatory-feasibility layer (CR_046 — the off-grid permitting register)

  • Water is the biggest household→community step-change. A shared reticulated supply is normally a registrable Taumata Arowai drinking-water supply (small networked = 26–100 people) unless kept within the ≤25-person shared-domestic carve-out — a parallel obligation on top of the RMA water-take consent. On-site wastewater needs an RMA s15 discharge consent unless a regional permitted standard is met (commonly ≤2,000 L/day; Canterbury LWRP Rule 5.8 requires ≤2,000 L/day AND site ≥4 ha), which a 5–100 HH settlement typically exceeds. An over-allocated catchment makes a new take effectively prohibited → forces rainwater/recycling. The full cross-domain framework (energy/water/building/Māori/site-triggers/costs/pending-law) lives on regulatory_consenting_off_grid_nz. CR_046

Food→water coupling — regenerative irrigation demand (CR_033, resolves RT_259)

  • A regenerative/permaculture NZ vegetable garden draws ~2.0 ML/ha/yr applied irrigation (200 mm ≈ 45% of the conventional 4.5 ML/ha, which D_001 forbids) — low–med confidence, built-up (no NZ peer-reviewed figure), and region-dominated: wet-west <1.0, dry-east 2.5–3.0 ML/ha/yr (set by summer PED 300–500 mm). This is a demand the water domain must meet on top of household use — veg_irrigation ≈ food_land_ha × ~2.0 ML/ha/yr — so a large garden in a dry-east region can push a community toward a D22 backstop. The model should scale by regional PED, not apply 2.0 flat. (Mulch’s “70%” is the evaporation slice only ~15–30% off seasonal irrigation; GROW BIOINTENSIVE’s “88%” is per-pound advocacy, not area-based.) CR_033

Forest Lodge Orchard — borehole + solar irrigation (CR_034, real-world D22 validation)

  • A consented borehole + 15–18.5 kW submersible pump + 2.3 mm drip supplies a UFO orchard needing ~2× a traditional orchard’s water (50–65k L/ha/day peak, up to ~390k L/day). Irrigation is a daytime load that matches solar (“the near-perfect use case”). Consent was obtained by arguing the UFO higher-water need, with efficient drip + a renewable focus easing the council’s over-allocation concern. Validates the model’s D22 borehole backstop + the water↔electricity pump-energy coupling + irrigation-as-summer-demand. See forest_lodge_orchard. CR_034

Roof-catchment pool floor area + storey mix (OT_123 — BRANZ SR501, verified primary behind CR_018; advances RT_206 → resolved / RT_304)

  • The rainwater-catchment area per dwelling (roof_catchment_per_dwelling_m2) is derived from new-house floor area: 2023 = 181.4 m² survey-weighted / 187.8 m² Stats NZ consent (Table 10), with 14% multi-storey (2+ storeys) in 2023 (§3 Flooring) — the storey correction that separates roof catchment from total floor area (a multi-storey dwelling’s ground footprint < its total floor area). Verifies the SR501 floor-area figures the compiled CR_018 carried, firming the catchment side of the Earthsong water-SSI validation (compact forms read ~110 m² vs the 170 default → water SSI −0.18). ⚠ Houses-only (single detached); the ~142 m² all-dwelling-types figure in the RT_206 note is NOT from SR501 (that is a Canstar / Stats-NZ-median figure carried in CR_018). OT_123

National drinking-water reticulation stock + condition — VERIFIES the ~NZ$23bn CR_050 rests on (LIT_074, peer-reviewed primary, verified)

  • **The ~NZ23bn drinking-water reticulation network value CR_050 cited is REAL and correctly attributed — but it is a repeated PRIOR estimate the paper argues is likely too low.** The first national standardised geospatial assessment of NZ's TA-owned drinking-water reticulation (66 of 67 TAs; 57,174 km of pipe; 625 of 629 WDZs serving 4,135,000 people ≈ 88% of NZ) states verbatim that *"drinking water reticulation networks could be worth ~NZ23bn and require NZ32–50bn of investment over the next 30 years"* (Introduction, p.35) — the exact figure behind [[cr_050_nz-offgrid-infrastructure-cost-reference|CR_050]]. ⚠ It is DERIVED top-down (NZ85bn total three-waters value [WICS 2021] × 27% drinking-water-networks share [Water NZ 2022]), not measured by this paper, and the paper’s central finding is that the deficit is a substantial underestimate. ⚠ The **3,300–5,000/connection is NOT in the paper** (a CR_050 synthesis derivation — the paper reports population served, not connections). Use 23bn as a national top-down floor, not a per-connection cost. LIT_074
  • The measured condition data (the paper’s own contribution, verified): 30.7% of NZ’s 57,174 km of TA reticulation is in poor/very-poor condition, 18.5% past life-expectancy, mean weighted age 37.8 yr; 81.1% distribution/rider mains + 12.2% service lines; 67.3% plastic + 19.8% asbestos cement; 46.2% over 40 years old. Condition varies 2.4–75.4% PVPC between TAs, worst in small rural TAs with small ratepayer bases (Kawerau 75.4% PVPC on a 7,100 supply population; Gisborne 58.7%) that cannot reach the estimated 600,000–800,000-person economies-of-scale threshold for viable centralised water delivery — the structural case for the community-scale decentralised water systems the D03 base already favours. LIT_074

Rainwater-as-majority-supply + high-recycling benchmark (Dancing Rabbit, USA — international comparator)

  • Dancing Rabbit (PRIMARY, Lockyer 2017): rainwater catchment supplies 65% of water (13 gal/59 L per capita/day of a 20 gal/91 L total), public mains 35% — the inverse of the average US community’s 87%-public/13%-self split; solid waste 0.2 lb/0.09 kg per person/day at a 73% recycling rate (vs US 34%); waste-reclamation covenant. A rainwater-as-majority-supply + high-recycling benchmark. ⚠ rainwater estimated (50–80% correction factor, unmetered); totals include business/ag use. LIT_081

Nutrient loop — excreta / urine recovery evidence (LIT_106 / 108 / 109 / 110)

  • Global excreta-nitrogen recovery potential — the magnitude anchor for the composting-toilet nutrient loop (transferable global proxy, no NZ value). Human excreta carried 31.8 Mt N/yr globally in 2020, of which 23.3 Mt/yr is recoverable after sanitary treatment (up +26.7% total / +17.7% recoverable on the 2000 baseline of 25.1 Mt; wet excreta mass 5.6 bn tonnes; India ≈4.3 / China ≈4.1 Mt N/yr) — a large, distributed, mostly-wasted N stream that, returned to soils, displaces synthetic fertiliser N and closes the nutrient loop. This is the global anchor behind the engine’s wastewater→food coupling: a composting toilet recovers excreta N, offsetting crop fertiliser-N (septic/AWTS discharge it to soakage, so recovery is gated on composting sanitation). ⚠ The engine’s EXCRETA_N_RECOVERABLE_KG_PERSON_YR = 3.0 is a DERIVATION (23.3 Mt ÷ ~7.8 bn people ≈ 2.99), not a per-capita figure the paper quotes. Abstract-only (paywalled); global aggregates, not NZ. LIT_106
  • Closing the vegetable nutrient loop cuts N leaching to water (Tei et al. 2020, Agric. Water Manag. review). The review frames vegetable N management around cutting N losses (nitrate leaching to surface/groundwater) by accounting for internally-cycled N: crop-residue N alone returns 25–30 kg N/ha (spinach/lettuce) to 250–300 kg N/ha (cabbages), 60–80% mineralised within 3 weeks of incorporation, so failing to count residue N drives over-fertilisation and leaching. Reinforces the closed-loop-nutrient case (residue recycling alongside digestate LIT_060 / composting). 🔴 Correction (carried from D02): this review does NOT support CROP_N_DEMAND_KG_HA["veg"]=150 — its “151 kg N/ha” is soil N-mineralization potential, not crop demand. ⚠ EU review — transferable mechanism, no NZ figures. LIT_108
  • International transferable proxy (France, no NZ value) — the excreta→fertiliser nutrient-loop METRIC, quantified. A national P mass balance of France’s ~20,000 WWTPs finds recycling all P in human excreta could supply 7-34% of the P in French domestic food supply (7% at the current animal-heavy diet → 34% if excreta-P is prioritised to plant-based human-food crops), or ~15% of direct P-fertiliser consumption (28.4 kt P/yr excreted vs 180-200 kt/yr consumed). ⚠ P only (no N figure); the 7-34% is a food-self-sufficiency metric (P in excreta ÷ the P footprint of domestic food supply), NOT a generic fertiliser-demand offset. Validates the excreta-nutrient-offset framing behind the composting-toilet / digestate nutrient-loop lever; recommend tightening the model wording to P-self-sufficiency. LIT_109
  • Human urine as a recoverable fertiliser — recovery efficiencies (transferable proxy, no NZ value). A PRISMA-2020 review of 123 studies (2011–2025) reports source-separated urine nutrient-recovery efficiencies of 50–95% for N, 40–99% for P, 80–98% for K, depending on stabilisation method and recovery pathway — corroborating the recoverable-nutrient envelope for the closed-loop / nutrient-recovery side of D03. ⚠ International review, secondary synthesis; use as a transferable proxy (same footing as LIT_060). LIT_110

SSI connections

  • I07 Fulfilment of basic needs — water is a fundamental basic need; WSR = Q_lr / Q_td is the primary water metric. CR_002
  • I09 Environmental sustainability — closed-loop water and waste systems reduce ecological impact; MFA self-sufficiency coefficient tracks material flows. CR_002
  • I01 Financial & economic sufficiency — on-site water and waste systems reduce utility costs.
  • I06 Resistance to external shocks — water independence protects against supply disruptions.

Connections

Links to

Sources (77): CR_002 · CR_004 · CR_005 · CR_016 · CR_018 · CR_032 · CR_033 · CR_034 · CR_039 · CR_041 · CR_045 · CR_046 · +65 more

Technologies (6): Biogas (community-scale,… · Groundwater (community-scale water … · community-scale seawater… · Greywater Recycling · Reticulated Water Connection (import w… · Rainwater Harvesting (Roof Collection & Dual R…

Concepts (2): EDT Framework — Emerging & Disruptive Technolo… · Regulatory Consenting for Off-Grid Communities…

Cases (1): Electric Cherries

Referenced by

Sources (33): CR_048 · CR_050 · CR_052 · LIT_007 · LIT_008 · LIT_063 · LIT_065 · LIT_074 · LIT_076 · LIT_086 · LIT_109 · LIT_130 · +21 more

Technologies (4): Biogas (community-scale,… · Groundwater (community-scale water … · community-scale seawater… · Reticulated Water Connection (import w…

Concepts (1): Regulatory Consenting for Off-Grid Communities…

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