The standard
The NEXUS Standard.
One public standard to verify linked impacts (water, energy, carbon, productivity) from a single measurement, each recorded separately and claimed once.One measurement, each impact recorded and claimed once.
02What the standard covers
One rulebook for every protocol.
NEXUS sets how impacts are measured, verified, recorded and claimed, across all protocols.Measured, verified, recorded, claimed.
- Protocols. One method per type of intervention, built on shared rules.One method per intervention.
- Verification. Independent bodies accredited under ISO/IEC 17029 sign every verification.Accredited, independent bodies.
- Registry. Each certificate is issued once and retired once.Issued once, retired once.
03Why a nexus standard
A litre saved is also energy and carbon.
Single-impact schemes lose the rest of the value, or count it twice. NEXUS measures once and keeps each impact in its own record.Measured once, each impact on its own record.
- Water. In cubic metres, the main impact.Cubic metres.
- Energy. In kilowatt-hours avoided.kWh avoided.
- Carbon. In tonnes of CO₂e avoided.tCO₂e avoided.
- Productivity. What each cubic metre makes possible.What a m³ makes possible.
04Integrity rules
The rules that do most of the work.
Six rules apply to every protocol, and code enforces them.Six rules, enforced by code.
- No composite score. Water, quality, biodiversity and carbon are never merged into one score or multiplier.Never merged into one score.
- One quantity, one claim. Each verified quantity is one registry entry, retired once, by one party.One entry, retired once.
- Shared formulas. Protocols call common calculation blueprints; they never rewrite them.Common blueprints, never rewritten.
- Context, never a multiplier. Basin stress is recorded and published; it never changes a certified volume.Recorded, never multiplied.
- Permanence follows physics. Flows and stocks are treated differently, by the nature of the activity.Flows and stocks, treated apart.
- Evidence before claims. Measured data first, declarations last; integrity checks run as deterministic code.Measured data first, checks in code.
05Governance
Separated by design.
Whoever writes the rules does not verify, and whoever verifies does not govern.Writing, verifying and governing kept apart.
- Veracity. Writes the rules and keeps the registry.Rules and registry.
- Accredited bodies. Verify, independently.Verify, independently.
- Standard and Protocols Committee. Governs the standard, with one technical sub-committee per protocol.Governs, a sub-committee per protocol.
- Public consultation. Every change that touches integrity goes to public consultation.Integrity changes go public.
06Aligned frameworks
We build on what already works.
NEXUS aligns with recognised frameworks rather than reinventing them.
- Water accounting
- VWBA 2.0
- ISO 14046
- WQBA
- BioBA
- Measurement and verification
- IPMVP
- ISO 14064-2
- ISO 14064-3
- Independent verification
- ISO/IEC 17029
- ISO 14065
- AI management
- ISO/IEC 42001
Data reusable in:CSRD · ESRS E3 · CDP Water Security · SBTN Freshwater · AWS Standard v3.0 · GRI 303 · CEO Water Mandate
07Get started
Read the standard. Then test it on a project.
The documentation sets out the rules, the shared formulas and the governance.Rules, formulas and governance.
+Questions
What is NEXUS?
The standard behind every Water Resilience Certificate. It verifies water, energy, carbon and productivity from one measurement and records each impact separately.
Why are impacts never added together?
Because each impact has its own unit and its own claim. Keeping them apart prevents double counting and hides no trade-off.
Who decides how the standard evolves?
The Standard and Protocols Committee, with one technical sub-committee per protocol. Changes that touch integrity go to public consultation.
Does basin scarcity raise the certified volume?
No. Basin context is recorded and published, but it never changes a volume.
Which frameworks does it build on?
VWBA 2.0, ISO 14046, WQBA, BioBA, IPMVP, ISO 14064-2 and 14064-3, ISO/IEC 17029, ISO 14065, with ISO/IEC 42001 for AI management.