NZ small community surface-water (stream) abstraction + treatment scheme cost stack (2026 Perplexity Deep Research synthesis)
Un-inerts the D28
stream_abstractionlever (RT_310) — the full surface-water cost stack, medium confidenceAI-prepared Perplexity Deep Research synthesis retrieved for RT_310: the NZD CapEx/OpEx of building and running a small community surface-water (stream/river) abstraction + treatment scheme for 20–100 households (~5–30 m³/day, up to ~1–2 L/s), component by component (intake · pump · DWSNZ treatment · RMA s14 take consent + Taumata Arowai registration), with borehole and mains comparators so the three D28 water-backstop options are cost-comparable. Headline: ~NZD 75,000–300,000+ CapEx / ~NZD 10,000–35,000+/yr OpEx (excl. reticulation to each house).
data_quality: medium— AI synthesis, values unverified until spot-checked. The consent bands tie to the corpus primary OT_111 (Beca/MfE) and the pump/borehole base data to OT_090 (MPDC/Brown Bros); the mains comparator to CR_032. The genuinely-new bits — intake CapEx (15–60k)** and **treatment CapEx (40–150k, ~5–8k/m³·day) + OpEx (1.50–4/m³) — are the synthesis’s own engineering estimates (no disclosed NZ small-scheme figure exists), flagged as such.
Summary
For a settlement of 20–100 households, a surface-water scheme is the most treatment-intensive of the three D28 water backstops: because the source is surface water, DWSNZ / Taumata Arowai rules require at minimum 5-micron (or finer) filtration plus a UV barrier (≥40 mJ/cm²) plus typically residual chlorination — materially more than a deep (>30 m) bore, which is exempt from the mandatory filtration rule. The synthesis stacks four components. Intake (screened weir / infiltration gallery): **15,000–60,000** CapEx — an *engineering estimate* extrapolated down from the only disclosed NZ comparator (a 100,000–400,000 irrigation-scale fish screen), two to three orders of magnitude larger. Pumping (abstraction pump + rising main + power): 15,000–50,000** CapEx + **500–3,000/yr OpEx — an estimate scaled up from disclosed single-property base data (1,250–4,000 pump + 1,000–3,000 reticulation, the MPDC/Brown Bros figures = OT_090). Treatment to DWSNZ (filtration + UV + chlorination, ± coagulation): 40,000–150,000** CapEx (~**5,000–8,000 per m³/day) + 1.50–4.00/m³** OpEx — *estimates*; no disclosed NZ small-scheme figure exists (FILTEC's AquaSAFE 25–100 m³/day packaged plant fits the scale but is unpriced). **Consent** (RMA s14 take + Taumata Arowai registration): **3,000–30,000 typical (up to 200,000 if notified/high-complexity), with the bands *disclosed* from the ORC 2025 fee schedule (~3,000 deposit) and the Beca/MfE CBA (= OT_111: low 10–30k, risk assessment 30k, compliance 2–20k/yr, reporting 5–15k/yr). Total: ~75,000–300,000+ CapEx / ~10,000–35,000+/yr OpEx for 20–100 households, excluding in-settlement reticulation. Confidence is mixed: consent + pump base data are disclosed; intake + treatment CapEx/OpEx are mostly estimated and should be firmed with a real FILTEC/Hydroflux supplier quote (already the standing RT_321 residual). The scheme is more expensive to build and to run than a deep protected bore (~20–50k/bore, minimal treatment) but far cheaper than a mains extension (~180k–2.1M+ in Watercare IGCs alone for 20–100 connections).
Key claims
- claim: "INTAKE STRUCTURE (screened weir / infiltration gallery) — CapEx NZD 15,000–60,000 for the full 5–30 m³/day scheme. ⚠ ENGINEERING ESTIMATE, not a disclosed cost: no NZ micro-scale intake cost is published; the figure is extrapolated DOWN from the only disclosed comparator — a new mechanical fish screen incl civil works at NZD 100,000–400,000 for a much larger irrigation-scale intake (Opihi Plains scheme feasibility, 2020 vintage) — two to three orders of magnitude bigger than a 5–30 m³/day community take. Fish-passage design standards (MfE Fish Passage Guidelines 2018 — avoid vertical drops, provide low-velocity margins) can raise intake civil cost where the waterway supports fish. OpEx (screen cleaning/debris clearance, structural inspection, mandatory monthly cyanobacteria inspection Oct–May for surface intakes) not separately disclosed — bundled into operator labour, estimated a few hundred to low thousands NZD/yr. Treat as INDICATIVE ONLY."
source_location: "§Component 1 (Intake) + Consolidated Summary; refs [^4] IrrigationNZ Opihi Plains fish-screen feasibility (disclosed comparator, 2020), [^5] MfE NZ Fish Passage Guidelines 2018 (regulatory), [^2] Taumata Arowai (cyanobacteria inspection rule)"
- claim: "PUMPING (abstraction pump + rising main + power) — scheme CapEx NZD 15,000–50,000 + OpEx NZD 500–3,000/yr (power + servicing). ⚠ SCHEME-SCALE FIGURE IS AN ESTIMATE scaled up from DISCLOSED single-property base data: submersible pump + installation NZD 1,250 (low) / 2,500 (mid) / 4,000 (high); reticulation/rising main NZD 1,000 / 2,000 / 3,000 — the 2025 Matamata-Piako DC Council-AI figures (= the same table held verbatim in the corpus as OT_090). A community scheme needs a larger-duty pump, longer rising main and standby/backup capacity, so the disclosed single-connection base is scaled up; no disclosed community-scale NZ pumping CapEx/OpEx was located. Pump technology is source-agnostic, so these bore-package figures are a reasonable proxy for a surface abstraction pump."
source_location: "§Component 2 (Pumping) + private-bore pump table; ref [^6] MPDC 'Session2 Bore drilling advice' PDF (= OT_090, Council-AI pump/reticulation table, 2025) — DISCLOSED base; scheme scale-up = estimate"
- claim: "TREATMENT TO DWSNZ (5-micron filtration + UV ≥40 mJ/cm² + chlorination, ± coagulation/clarification pre-treatment) — CapEx NZD 40,000–150,000 (~NZD 5,000–8,000 per m³/day of design capacity, unit cost falling toward 30 m³/day) + OpEx NZD 1.50–4.00/m³ (power, chemicals, filter/UV-lamp replacement, routine monitoring). ⚠ BOTH FIGURES ARE ENGINEERING ESTIMATES, not disclosed: no NZD capital cost per m³/day was found for a 5–30 m³/day plant; the nearest commercial comparator (FILTEC 'AquaSAFE', explicitly for rural schools/marae/remote communities, 25–100 m³/day, filtration+UV+IoT to DWSNZ) is UNPRICED publicly. The REGULATORY FLOOR is disclosed/confirmed real: Taumata Arowai's post-Sept-2025 Acceptable Solution for small-medium networked supplies (≤500 people) mandates ≥5-micron filter + UV ≥40 mJ/cm² at every connection, backflow prevention, and a cyanobacteria risk/response plan for surface sources; coagulation/clarification is an added step where raw-water turbidity is high (common on stream sources in rain). Monitoring (disclosed rule, dollars estimated): quarterly E. coli/total-coliform + turbidity on treated water; 3-yearly pH/turbidity/iron/manganese/nitrate/arsenic/boron — lab costs 'low thousands NZD/yr' (estimate). Should be treated as a planning-level placeholder pending a supplier quote (FILTEC, Hydroflux Epco)."
source_location: "§Component 3 (Treatment) + Consolidated Summary; refs [^3] Taumata Arowai Acceptable Solution / DWQAR (regulatory floor — DISCLOSED), [^9] FILTEC AquaSAFE (comparator, unpriced), [^10] Hydroflux — CapEx/OpEx = ESTIMATE"
- claim: "CONSENT — RMA s14 surface-water TAKE + Taumata Arowai registration. DISCLOSED figures: Otago RC 2025 schedule — standalone water-take application deposit ~NZD 3,000 (or ~NZD 3,200 combined take-and-divert), bore/structure inspection ~NZD 400, ongoing annual compliance/telemetry admin ~NZD 62–290/yr by metering type; historic MfE two-yearly RMA survey — non-notified water consents median NZD 350–598 (notified can run into the thousands). Beca/MfE CBA of the amended NES-DW (2022, real disclosed bands from rural + marae case studies = the corpus primary OT_111): low-complexity resource-consent application NZD 10,000–30,000; medium 30,000–50,000; high (notified/contested) 50,000–200,000; source-water risk assessment NZD 30,000 (separate line); consent compliance monitoring & enforcement NZD 2,000–20,000/yr; resource-consent reporting NZD 5,000–15,000/yr; processing of changed consent status NZD 3,000–16,000. Taumata Arowai registration itself (Hinekōrako portal + Drinking Water Safety Plan) has NO disclosed fixed fee — a compliance obligation, with DWSP prep (often consultant-engaged) + ongoing monitoring the real annual cost. Consent cost scales with complexity/notification, not flow rate. Typical band NZD 3,000–30,000; a new community surface take with ecological/fish-passage effects is more likely notified → the higher Beca bands apply."
source_location: "§Component 4 (Consent) + Beca cost table; refs [^11] Otago RC 2025 fees (DISCLOSED), [^13] MfE RMA two-yearly survey (DISCLOSED historic), [^14] Beca/MfE NES-DW CBA case studies (= OT_111, DISCLOSED bands verbatim), [^1][^2] Taumata Arowai registration (no fee disclosed)"
- claim: "CONSOLIDATED SURFACE-WATER SCHEME TOTAL (20–100 households, ~5–30 m³/day, EXCLUDING reticulation to each house): CapEx ~NZD 75,000–300,000+ (sum of intake 15–60k + pump 15–50k + treatment 40–150k + consent 3–30k); annual OpEx ~NZD 10,000–35,000+ (pumping, treatment, monitoring, compliance). CONFIDENCE MIXED: consent and pump base figures are disclosed; intake and treatment CapEx/OpEx are mostly ENGINEERING ESTIMATES. No NZ source reviewed disclosed a fully itemised, real (not modelled) capital cost for a complete small community surface-water scheme at this scale — this total combines disclosed component bands with engineering-estimate intake/treatment, and should be validated with a direct supplier quote before budgeting."
source_location: "§Consolidated CapEx/OpEx Summary table + §Cross-Option Cost Comparison (surface-water row) + §Key Uncertainties and Data Gaps"
- claim: "CROSS-OPTION COMPARATORS (for cost-comparability of the three D28 backstops). BOREHOLE (deep bore + pump): ~NZD 20,000–50,000 per bore, likely 1–3 bores for 20–100 HH; minimal/no filtration if >30 m deep and protected (DWSNZ exempts groundwater >30 m); DISCLOSED drilling anchors — council-published 64 m bore (drilling only) NZD 21,440 excl GST (= the Brown Bros/MPDC quote, OT_090), WeDrill setup excl drilling NZD 8,000–20,000, lifestyle-block bores NZD 8,000–30,000; a bore also largely avoids in-stream fish-passage consent complexity (ORC single-bore construction fee NZD 1,365). CAVEAT: a shallow (<30 m) or surface-influenced bore attracts the SAME filtration/UV rules, removing the treatment-cost advantage. MAINS connection (where available): ~NZD 180,000–2,100,000+ for 20–100 connections at the Watercare 2024 Infrastructure Growth Charge NZD 21,174.95 incl GST/unit (water+wastewater; ~NZD 9,254 water-only), plus site-specific pipe-extension; volumetric ~NZD 3.994/m³ + fixed NZD 332/yr (Watercare 2025/26), Water NZ national median NZD 465/HH/yr drinking water (range 244–1,209), ~NZD 850/HH/yr water+wastewater. These borehole + mains figures are the best-disclosed in the report and tie to OT_090/CR_045 (borehole) and CR_032 (mains)."
source_location: "§Borehole Comparison + §Mains Connection Comparison + §Cross-Option Cost Comparison; refs [^6][^15][^16] borehole (= OT_090 + CR_045), [^17][^18][^19][^20][^21] Watercare/Water NZ (= CR_032 territory), [^11] ORC single-bore fee"NI relevance
This is the direct cost source that lets the D28 stream_abstraction lever be un-inerted (RT_310). The lever exists in the engine but is inert (audit AF-11 / decision D-e 2026-07-08): riverside probe sites read water-infeasible while micro-hydro uses the same stream. Its two regulatory bounds are already sourced — the take-volume ceiling (naturalised 7-day MALF: 90% minimum flow + 20–30% allocation) from OT_100, and the dry-year availability caveat (councils cease consented surface takes below minimum flow — the take is switched off exactly when demand peaks) from OT_099. What was missing was the cost to build and run the take. This synthesis supplies it as a full four-component stack — intake + pump + treatment + consent → ~75–300k CapEx / ~10–35k/yr OpEx for 20–100 HH — a medium-confidence cost band the model can wire into the cascade so a riverside site is no longer read as flatly water-infeasible.
Cost-comparability across the three backstops (the model’s ranking basis). With this source the D28 cascade can rank all three fallbacks on a like basis:
| Backstop | CapEx (20–100 HH) | OpEx | DWSNZ treatment | Corpus anchor |
|---|---|---|---|---|
| Surface-water take (this source) | ~$75–300k+ | ~$10–35k/yr | Mandatory filtration + UV (costliest) | CR_053 |
| Borehole (deep, protected) | ~$20–50k/bore, 1–3 bores | Low (pump energy) | None if >30 m + protected | [[ot_090_mpdc-brown-bros-bore-drilling-costs |
| Mains (where available) | ~$180k–2.1M+ IGCs + extension | ~$465–850/HH/yr | Provided by operator | [[cr_032_nz-water-backstop-costs-2026 |
The ordering is intuitive and now quantified: a deep bore is cheapest to build and run (no filtration), surface water is mid-cost but treatment-heavy (the filtration+UV premium is exactly why it sits above the bore), and mains is a step-change once you multiply the per-connection IGC across a settlement. This mirrors the self-sufficiency-order energetics in LIT_063.
How the disclosed vs estimate split maps to model trust. Two of the four components (consent, pump base) are disclosed and tie to primaries already in the corpus — so those cells inherit those primaries’ provenance, not this synthesis’s:
- Consent bands = OT_111 (Beca/MfE Table 3-1 — the low-complexity
10–30k application +30k risk assessment + $2–20k/yr compliance are OT_111’s verbatim figures, already the source under the engine’swater_take_consent_capex). Cross-referenced, not re-ingested. - Pump + borehole base = OT_090 (the MPDC/Brown Bros pump/reticulation table + the $21,440/64 m drilling quote). Cross-referenced, not re-ingested.
- Mains comparator = CR_032 (Watercare IGC $21,175 + tariff). Cross-referenced.
The intake (15–60k)** and **treatment (40–150k, ~5–8k/m³·day; OpEx 1.50–4/m³) are the synthesis’s own engineering estimates — no disclosed NZ small-scheme figure exists, so any model cell drawing on them must carry an explicit estimate / low-confidence flag and cite this cr_ page (medium), not a primary. The treatment per-m³·day estimate corroborates CR_050’s triangulated ~2,000–8,000/m³·day surface-water treatment band (this source's 5,000–8,000/m³·day sits in CR_050’s upper half) and, crucially, adds the intake + pump + consent components CR_050 lacked — assembling CR_050’s treatment-only “first cost band” for stream_abstraction into the full scheme stack.
Estimate caveat on the two headline CapEx components
The intake (
15–60k)** and **treatment (40–150k) figures — the largest single CapEx lines after treatment — are engineering extrapolations, not disclosed NZ costs. Intake is scaled down from a 2020 irrigation fish-screen ($100–400k, 2–3 orders of magnitude larger); treatment is general packaged-plant industry knowledge (FILTEC AquaSAFE fits the 25–100 m³/day scale but is unpriced). Firm both with a real FILTEC/Hydroflux supplier quote before any budgeting use — this is the standing RT_321 residual (already Open), not a new gap.
Retrieval provenance
Values AI-extracted, unverified until spot-checked. This synthesis was compiled by Perplexity Deep Research — an AI research tool, not an authoritative disclosed document — so data_quality: medium at best until each figure is verified against its upstream. The report itself flags every figure as disclosed vs estimate; the estimate components (intake CapEx, treatment CapEx/OpEx, scheme-scale pump CapEx) carry no disclosed NZ small-scheme source. The disclosed components have been cross-referenced to corpus primaries during ingest (consent → OT_111; pump/borehole → OT_090; mains → CR_032) rather than re-verified from scratch. A _retrieval.md sidecar repeating this block is filed in the raw store alongside the .md.
Exact prompt run (verbatim):
Research question: What does it cost, in New Zealand, to build and run a small community-scale surface-water (stream/river) abstraction and treatment scheme — for a settlement of roughly 20–100 households (~5–30 m³/day to ~1–2 L/s)?
Find NZD figures for each component, separating capital (CapEx) from operating (OpEx), and state the scheme size each figure refers to:
- Intake structure — screened river/stream intake, weir or infiltration gallery (CapEx per scheme; typical size range).
- Pumping — abstraction pump + rising main + power (CapEx and annual OpEx / kWh).
- Treatment to NZ drinking-water standards — for surface water this means at minimum coagulation/filtration + protozoa barrier + UV/chlorination (Taumata Arowai / DWSNZ requirements). CapEx per m³/day and OpEx per m³.
- Consent — the resource-consent (RMA s14 water-take) cost basis for a small community surface-water take, and any Taumata Arowai registration/compliance cost for a supply of this size.
Prioritise these NZ sources: regional-council water-take + small-supply guidance; Taumata Arowai small drinking-water supply cost/compliance guidance; rural/community water-scheme cost disclosures and asset-management plans (small rural schemes, irrigation-scheme intakes); Water New Zealand; NZ engineering cost references (Beca / WSP / GHD small-WTP costings); any published small-community WTP business case.
Report: component-by-component NZD CapEx + OpEx with the scheme scale each applies to; a per-m³/day CapEx and per-m³ OpEx where derivable; and an explicit note on whether treatment-to-DWSNZ is included (surface water needs far more treatment than a bore). Contrast briefly with the borehole option (bore + pump, RT_260) and mains connection (RT_261) so the three water-backstop options are cost-comparable. Flag every figure’s vintage and whether it’s a real disclosed cost or an estimate.
Research targets
Research gaps
- RT_310 — RESOLVED-WITH-RESIDUAL → CR_053 (kept OPEN, annotated in place). The stream-abstraction intake/treatment cost gap is now substantially delivered: the full surface-water cost stack (intake + pump + treatment + consent → ~
75–300k CapEx / ~10–35k/yr OpEx for 20–100 HH) is held at medium confidence, enough to un-inert the D28stream_abstractionlever. RESIDUAL (narrow): a real FILTEC / Hydroflux (or similar NZ packaged-plant vendor) supplier quote for the intake + treatment train, to lift those two engineering-estimate components from medium to sourced. That residual is already tracked by the existing RT_321 (FILTEC CIP rural modular programme — the retrievable treatment-capex primary behind CR_050), so no new RT is minted. RT_310 stays Open only until RT_321 lands. UPDATE 2026-07-20: RT_321’s FILTEC programme page is now retrieved (URL_027) and is UNPRICED — it confirms the 25–100 m³ AquaSAFE-class modular scale but discloses no cost, so the residual is NOT closed; it now specifically needs a PRICED FILTEC/Hydroflux supplier quote, not the programme page.
Notes
AI-prepared Perplexity Deep Research synthesis → data_quality: medium; figures unverified until spot-checked. Stored as a subfolder (raw .md + _retrieval.md sidecar) under source-files/02_compiled_research/. context: ni — the value is the cost band for the D28 water cascade.
Disclosed-figure cross-references confirmed at ingest (not re-ingested):
- The Beca/MfE consent table in this synthesis (ref [^14]: low
10–30k, medium30–50k, high50–200k, risk assessment30k, compliance2–20k/yr, reporting5–15k/yr, processing $3–16k) is verbatim OT_111 Table 3-1. - The pump/reticulation base table (ref [^6]: submersible pump
1,250/2,500/4,000; reticulation1,000/2,000/3,000) and the $21,440/64 m bore quote are OT_090 (MPDC/Brown Bros). - Watercare IGC $21,174.95 + tariff are the CR_032 upstream.
⚠ Minor cross-ref discrepancy to flag (not model-critical): this synthesis cites the Watercare 2025/26 residential volumetric tariff as NZD 3.994/m³ (ref [^17], residential_other_charges_2025_2026 PDF), whereas CR_032 recorded NZD 2.30–2.46/m³ (from the “Prices to increase 1 July 2024” page). The gap is likely a water-only vs water+wastewater split or a subsequent tariff step; it sits in the mains comparator (not the RT_310 surface-water core), so it does not affect the stream_abstraction cost band — but the Watercare volumetric cell should be reconciled the next time the mains backstop is touched.
⚠ Estimate honesty: the two largest surface-water CapEx components (intake, treatment) are engineering estimates with no disclosed NZ small-scheme source. The un-inerted lever therefore carries a genuine estimate risk — appropriate to flag as a tool limitation until RT_321’s supplier quote lands. RT_321’s programme page landed unpriced (2026-07-20), so the supplier-quote residual persists.
Connections
Links to
Referenced by
EDT domains (1): D03: Water, Waste & Circular Systems