NVWS-SAVE-001 — Direct-meter building water conservation

DRAFT FOR CONSULTATION. NVWS v0.1 (October 2026). This is a proposed Nexus Water DAO LLC standard. It is not approved, adopted or independently assured. The methods have not been approved by an independent technical council. No Verified Water Credits (VWC) have been issued, and none are offered for sale. References to WRI, AWS, Gold Standard, ISO, EPA, FTC, SEC, CFTC or any other organization are not endorsements. Comments: josh@nexuswater.xyz

Version 0.1 · 2026-10-03 · Nexus Water DAO LLC

Status: proposed Nexus policy / technical draft. Not an approved or independently assured credit standard.

Required methodology specification

Field	Proposed requirement
1. Methodology ID	NVWS-SAVE-001
2. Version	0.1-draft; proposed, not approved
3. Effective date	None for live issuance; draft baseline 2026-10-03
4. Eligible activities	Metered building/process leak repair, fixture retrofit, cooling optimization with an isolated boundary. Initial pilot excludes agricultural irrigation, distribution-wide pressure changes and unmetered portfolio extrapolation.
5. Geographic applicability	Pilot-specific only after local permit, source-catchment and technical applicability review; no blanket global approval.
6. Environmental objective	VWC-SAVE; withdrawal_avoided; consumption_avoided only with a separately validated return-flow model
7. Project boundary	Whole facility or isolated submetered end use with all alternative sources, discharge, storage and operating changes reconciled.
8. Water source	Identify actual conventional source catchment(s), intake and discharge pathways. A utility billing district is not necessarily its source catchment.
9. Baseline rules	Use a representative continuous pre-intervention history, preferably at least 12 months for seasonal sites; the applicable program may require 24–36 months or another justified counterfactual. Freeze an approved occupancy/production/weather normalization before outcome evaluation. A short baseline requires a documented technical case; it is not automatically eligible.
10. Additionality rules	Apply the NVWS additionality policy (draft, publication pending); environmental counterfactual, regulatory and temporal tests required; method/project annex specifies practice and finance tests with evidence and rationale.
11. Monitoring	Calibrated boundary meter; actual utility reads; occupancy/production/weather series; intervention and repair dates; alternate supplies; return flow where relevant. Compare aligned intervals and demand units.
12. Devices	Calibrated, appropriately sized/installed meters with serial, unit, accuracy specification, commissioning and calibration history. Approved engineering models where the project annex permits; no brand endorsement implied.
13. Equations	G = max(0, B_adj − P_adj). E = max(0, G − U − L) × A. Issue floor(E) whole units. B_adj and P_adj are comparable m³; U and L are distinct m³ deductions; A is an approved fraction in [0,1].
14. Uncertainty	Project annex defines uncertainty budget, missing-data rule, correlation/error propagation and chosen conservative deduction. No default confidence factor from evidence tier. Technical reviewer must approve parameters before real issuance.
15. Leakage / adverse effects	Reduced withdrawals may reduce sewer return and leave consumptive use unchanged. If consumption is the target, quantify baseline and project consumptive use with the same boundaries; do not silently relabel a withdrawal result. Deduct shifted use and rebound attributable to the intervention.
16. Allocation	Explicit rights and pool-level allocation ≤100%; apply only once after conservative physical quantity. Coordinate utility and sponsor shares.
17. Data quality	Immutable originals, aligned periods, explicit units/read types, calibrated instruments, anomaly resolution and source reconciliation; no unresolved material gaps.
18. Verification	Independent qualified verifier and separate registry review; bind decision to exact baseline, calculation and evidence versions.
19. Issuance schedule	Ex-post only, on complete approved monitoring intervals. One annual vintage is preferred where seasonal comparability requires it; no automatic annualization from a short sample.
20. Crediting period	Project-specific, with annual eligibility/maintenance review. No guarantee of future issuance. Material baseline/operating change triggers revalidation.
21. Reversal/correction	Later equipment failure stops future crediting; it does not automatically negate a valid past measured reduction. If prior data or hydrological conclusions were wrong, investigate, cancel active units and invalidate retired claims with append-only history. Stored or time-dependent benefit annexes must define actual reversal obligations.
22. Reporting	Publish redacted PDD, method/version, boundary, metric, vintage, calculation, uncertainty, allocation, verifier opinion, serial batch and separately disclosed co-benefits.
23. Claim language	Verified eligible freshwater withdrawal avoided; consumption savings only when the approved calculation actually measures that metric.
24. Exclusions	Shutdowns, occupancy drops without normalization, mandatory baseline improvements without additional increment, meter estimates treated as actual, unresolved resets, Tier D, unsupported return-flow equivalence.
25. Double counting	Use the same physical outcome pool across overlapping methods; detect overlapping dates, evidence/meters and external claims. Apply the NVWS double-counting policy (draft, publication pending).
26. Update history	2026-10-03: first technical draft based on user brief; no technical council approval, field validation or public consultation completed.

Worked example

HYPOTHETICAL EXAMPLE: baseline 100,000; project 82,000; gross 18,000. An eligibility exclusion of 1,200 and an illustrative 840 m³ uncertainty deduction yield 15,960 m³ at 100% allocation. These deductions are assumptions requiring review, not a universal five-percent rule.

Approval blockers

Live issuance is disabled until a competent reviewer approves the specific baseline, boundary, uncertainty treatment, data-completeness criteria, measurement specifications, rights, safeguards and legal applicability. Publish technical consultation and council disposition. Examples and software calculations are not field validation. The REPLENISH methodology additionally requires an executable, independently reviewed site-specific hydrological annex.

Technical reference use

Use WRI VWBA 2.0 and applicable source-specific engineering as accounting references, not as certification of this formula. Consider AWS site/catchment context, EPA WaterSense specifications for applicable SAVE products, WQBA for quality effects and GHG Protocol for separately quantified carbon co-benefits. See the Nexus reference library (publication pending).