ISO 24521:2025

This document provides guidance and requirements for the management of on-site domestic wastewater systems and services, using appropriate technologies in their entirety at any level of development.

This document supplements and is intended to be used in conjunction with ISO 24511 and ISO 24525. It includes guidance and requirements for the following:

—     management of on-site domestic wastewater systems and services from the operator’s perspective, including maintenance techniques, training of personnel and risk considerations;

—     management of on-site domestic wastewater systems (ODWS) from the perspective of owners and users;

—     design and construction of ODWS;

—     planning, operation and maintenance, and health and safety issues.

This document is applicable to both publicly and privately operated on-site domestic wastewater (black and grey water) services, for one or more dwellings. In rural areas and areas under development, management is sometimes provided by the owners of the premises where wastewater is generated. In this document the term “services” includes “self-services” provided by the owners of the premises.

The following are outside the scope of this document:

—     limits of effluent quality for wastewater discharged into the environment;

—     analytical methods;

—     stormwater runoff;

—     content of contracts or subcontracts.