Source
https://www.earthsong.org.nz/resources/documents — original source (opens in a new tab; the file is not redistributed)
Earthsong Eco-Neighbourhood — Water Supply System Performance 2005-08
Real measured NZ community water performance — validates the D03 water model
The performance companion to OT_078 (the water-system costs) and INT_006 (the Interviewee account): four years of metered dual-reticulation data from a 32-home Auckland cohousing community. Directly cross-checks the model’s
person_water_demand, the rainwater-offsettable fraction, and the tank-sizing →water_ssiseasonal balance. Primary Earthsong technical report (July 2010), figures read from the PDF → data_quality high.
Summary
Four years (2005–08, metered from Dec 2004) of water-supply performance at Earthsong, a 32-home Auckland eco-neighbourhood with a dual-reticulation rainwater + city-mains system. Roof water from all buildings feeds 6 × 32,000 L concrete tanks (192,000 L total, each serving 6–7 households) supplying everything except drinking water (kitchen + bathroom-basin cold taps stay on city mains for potable compliance); when a tank runs dry a manual valve sends city water down the tank line. Measured average water use ~174 L/p/d (range 144.0 in 2004 to 192.9 in 2006) — 58–80% of the Auckland regional figure (~240–247 L/p/d) and 72–96% of Waitakere City (~180–214, the region’s lowest-use city). On-site rainwater met ~50% of the community’s water (below the 70% design target) — constrained by land area limiting tank volume. Both stated targets (50% of normal use; 70% on-site) were missed, but the reduction is still real (~20–42% below regional). Water-saving fittings: 3/6 L dual-flush WCs, 9 L/min showers, 7 L/min taps.
Key claims
- claim: "MEASURED WATER USE (L/p/d, 2005-08). Earthsong average annual water use ranged 144.0 (2004) to 192.9 (2006) L/p/d, ~174 L/p/d mid-period — 58.3–80.3% of the Auckland regional figure (~240–247 L/p/d) and 72–96% of Waitakere City (~180–214 L/p/d, the region's lowest-use city). Target #1 (50% of 'normal' urban use) was NOT met; the actual reduction was 19.7–41.7% below regional and 3.8–27.7% below Waitakere. Metered dual-reticulation, E-F blocks (Units 14–20), Dec 2004–Jan 2009; L/p/d converted from m³ using block occupancy."
source_location: "Data analysis & results; Table 1 Water Use Regional Comparison 2005-08"
- claim: "ON-SITE RAINWATER CONTRIBUTION ~50% (below the 70% target). Metered 'city water' (potable + mains sent down the tank line when tanks are dry) was 57.2–109.3 L/p/d, so on-site tank rainwater supplied roughly 37–60% of Earthsong's water (mid-period ~50%) — below the 70% design target because land area limits tank volume (fully rain-reliant would need several times more storage). When a tank empties after a dry spell a manual valve routes city water down the 'tank water' line for uninterrupted supply."
source_location: "Water targets; Data analysis & results (Earthsong City Water row, Table 1); reticulation system"
- claim: "SYSTEM DESIGN (real NZ dual-reticulation spec). 6 × 32,000 L concrete tanks (192,000 L total; ~6,000 L/home) collect roof water via 100 mm plumbing, each tank serving 6–7 households plus communal garden taps + common house. Dual supply per house: POTABLE (kitchen sink + bathroom basin cold taps) direct from city mains; NON-POTABLE (hot water, shower, bath, WC, laundry, outside tap) from the tank line. Water-saving devices: 3/6 L dual-flush WCs, showers pre-set to 9 L/min, other taps 7 L/min. Tank water pumped by dual submersibles (0.75 + 1.5 kW, 160 L/min combined at 30 m head)."
source_location: "Introduction; reticulation system; water monitoring system"
- claim: "TARGETS vs OUTCOMES + charging. Two design targets: (1) 50% of 'normal' urban residential use; (2) 70% of needs from on-site rainwater → only 15% drawn from city mains. Neither was fully met (actual ~20–42% reduction; ~50% on-site) — but a significant real reduction for a dense-urban site. The Body Corporate charges households by metered tank-line use on a two-stage seasonal tariff (summer first 3 m³/HH/month at a lower rate; winter first 8 m³) reflecting the higher mains share in summer."
source_location: "Water targets; Earthsong water charging system"Neobiome Intelligence relevance
Validates the D03 water model with real measured NZ community data — the performance counterpart to the costs (OT_078) and the Interviewee account (Interview VI [INT_006]). Three artefact cross-checks:
person_water_demand: Earthsong’s ~174 L/p/d (range 144–193) sits right around the model’s OT_036 BRANZ median (159 winter / 231 summer, ~195 blend) — a lived-community datapoint confirming the ~175–195 L/p/d assumption, and notable that a water-conscious community still lands there.- Rainwater-offsettable fraction + supply cap: on-site rainwater met ~50%, not the 70% target, because tank volume is land-limited — a direct real-world validation of the model’s rainwater-supply cap and the “runs dry every summer” backstop logic (INT_006, RD_023 seasonality). The dual-reticulation split (drinking from mains; hot water/shower/bath/WC/laundry/outside from tank) sets the non-potable fraction the model’s rainwater can actually offset.
- Tank sizing →
water_ssi: 192,000 L across 32 homes (~6,000 L/home installed) yielding only ~50% self-sufficiency in Auckland’s climate is a hard anchor for thetank_m3→ seasonal water-balance calc (complements RD_023 monthly rainfall + OT_030).
data_quality high (measured primary). Feeds D03 and the earthsong_ranui case. No new research targets — this is validation evidence.
Research targets
Research gaps
- None — measured primary that validates existing model assumptions.
Connections
Links to
Sources (1): OT_078
Cases (1): Earthsong Eco-Neighbourhood
EDT domains (1): D03: Water, Waste & Circular Systems
Referenced by