ISO 24528:2021

Overview

ISO 24528:2021 - "Service activities relating to drinking water supply, wastewater and stormwater systems - Guideline for a water loss investigation of drinking water distribution networks" provides a standardized methodology for conducting water loss investigations in drinking water distribution networks. The standard establishes principles for water loss management to improve utility sustainability and protect the environment by saving water, energy and chemicals. It defines procedures to estimate water loss components using water balance calculations and guides the preparation (but not execution) of a water loss management plan. ISO 24528:2021 applies to public drinking water distribution networks and can be used analogously for non‑public supply, raw water and industrial water systems.

Key technical topics and requirements

• Water loss investigation steps and scope definition - set objectives, define investigation area and time period, and select measurement units.
• Data collection and validation - methods for collecting, validating and rating data quality used in water balance calculations.
• Water balance calculation - procedures and parameters to quantify system input, exported water, billed and unbilled authorized use, non‑revenue water, apparent water loss and real water loss.
• Performance indicators - selection and purposes of indicators to monitor and benchmark water loss.
• Apparent vs. real water loss assessment - approaches for analyzing metering and billing errors, unauthorized use, background leakage, reported/unreported losses, bursts and overflows.
• Cost assignment - methods to estimate the economic impact of apparent and real water losses.
• Water loss management planning - general principles for preparing management plans, including district metered areas (DMA), active leakage control, pressure management, maintenance and rehabilitation planning.
• Informative annexes - practical guidance on measurement methods, factors affecting leakage, Economic Leakage Level (ELL), leak detection technologies, night flow analysis, and uncertainty assessment.

Practical applications and users

Who uses ISO 24528:2021:

• Drinking water utilities and operators
• Asset and network managers responsible for non‑revenue water reduction
• Consultants and engineers performing leakage assessments and DMA design
• Regulators and policymakers developing performance targets and benchmarking
• Industrial water managers adapting the methodology for non‑public systems

Practical uses:

• Conducting systematic water loss investigations and producing defensible water balances
• Prioritizing investments (leak detection, pressure control, meter replacement) based on cost impacts
• Designing DMA programs and active leakage control strategies
• Comparing performance using standardized indicators for reporting and benchmarking

Related standards

ISO 24528:2021 is published by ISO/TC 224 and complements other ISO and national guidance on water services, non‑revenue water and asset management practices. Users should consider coordination with local regulations and related ISO guidance for comprehensive water utility management.