ISO 9111:2024

Overview

ISO 9111:2024 - Water reuse in urban areas - Guidelines for benefit evaluation of reclaimed water use provides a structured, practical framework to assess the benefits of using reclaimed water in urban contexts. It guides practitioners and authorities on how to quantify and compare reclaimed-water options against baseline scenarios, supporting water reuse planning, design, operation and management. The standard focuses on benefit indicators, evaluation procedures and examples; design parameters, regulatory values and risk/safety assessments are explicitly out of scope.

Key topics

• Holistic indicator system organized into four categories: resource, ecological & environmental, social, and economic benefits.
• Resource indicators: conventional water resource savings, energy recovery, carbon recovery, phosphorus recovery (includes example calculation formulas and methods for quantifying recovered heat/cold and resource substitution).
• Ecological & environmental indicators: reductions in contaminants, electricity use and GHG emissions; achievement of environmental flows (E‑flows); ecosystem protection/restoration.
• Social indicators: improvement of local and regional natural environments, with illustrative indicators in Annex A.
• Economic indicators: avoided cost, net present value (NPV), internal rate of return (IRR), life‑cycle considerations.
• Procedures: stepwise benefit evaluation flow chart, procedures, and scenario‑based guidance (Annex B) to ensure consistent comparisons between reuse options and baselines.
• Normative and referenced documents: includes ISO 20670 (vocabulary); risk assessment guidance is referenced (e.g., ISO 20426, ISO 20761) but detailed safety evaluation is out of scope.

Practical applications

ISO 9111:2024 is designed to be used where reclaimed water is considered for non‑potable and beneficial urban uses such as landscape irrigation, ecological flow replenishment, toilet flushing, firefighting, and other municipal uses. Typical uses:

• Supporting decision‑making and cost‑benefit analysis in water reuse planning and project appraisal.
• Guiding engineers and consultants in design option comparisons and life‑cycle evaluations.
• Helping utilities and local authorities quantify resource savings, environmental co‑benefits, and social value for funding, permitting or stakeholder engagement.
• Informing policy makers on standardized indicators to compare reuse schemes across projects or regions.

Related standards

• ISO 20670 - Water reuse - Vocabulary
• ISO 20426, ISO 20761 - referenced for reclaimed water risk assessment and safety management (for implementers needing detailed risk guidance)

ISO 9111:2024 supplies a practical, indicator‑based approach to make reclaimed water benefits transparent and comparable, enabling more informed urban water‑reuse decisions.