NVWS-REUSE-001 — Beneficial reuse and conventional-source displacement

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-REUSE-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 greywater, reclaimed municipal supply or industrial reuse that demonstrably substitutes a defined eligible conventional source. Identify the actual quality requirement for the end use.
5. Geographic applicability	Pilot-specific only after local permit, source-catchment and technical applicability review; no blanket global approval.
6. Environmental objective	VWC-REUSE; source_displacement with explicit withdrawal/consumption interpretation
7. Project boundary	Reclaimed source, treatment, conveyance, storage, end use, conventional intake and displaced discharge/return pathway. Do not double count upstream treatment and downstream substitution as one indistinguishable volume.
8. Water source	Document reclaimed source catchment and displaced conventional source catchment, end-use destination and any interbasin transfer.
9. Baseline rules	Establish comparable end-use demand without the reuse project, normalized for production/occupancy/weather. Include pre-existing reuse and water quality constraints. No credit for pre-existing circulation counted again.
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	Paired reuse-delivery and conventional-source meters, treatment losses, storage changes, bypasses, conventional purchases, quality samples, operating demand and discharge.
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 = min(R_eligible_used, D_eligible). E = max(0, G − U − L) × A. R and D are verified comparable m³ within the same period; exclude recirculation already counted. Issue floor(E).
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	Identify foregone return flows, changed consumption, upstream competing uses and energy effects. If reclaimed supply was already sustaining another downstream use, that effect cannot be ignored. Do not apply an unexplained generic quality factor; exclude non-qualifying volume using the approved quality rule.
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 substitution of the named conventional source through beneficial reuse; no automatic aquifer-recharge claim.
24. Exclusions	Nameplate capacity, repeated internal cycles without displacement, additional demand represented as avoided supply, noncompliant quality, unresolved return-flow harm.
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: reclaimed delivery 300,000 m³ and normalized eligible conventional displacement 292,000 m³ give a gross ceiling of 292,000. Final issuance is at most that value and is lower if uncertainty, adverse effects or allocation require deductions. Separate test fixture: 54,000 delivered, 52,000 displaced, 2,000 deducted → 50,000 eligible.

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).