This document provides guidance and specifications for the operation and maintenance (O&M) of on-site domestic wastewater services, using appropriate technologies at any level of development. This document supplements and is intended to be used in conjunction with ISO 24513 and ISO 24521.This document provides assistance to relevant authorities, training organizations, certification bodies and other responsible entities for the development of regulations, plans and manuals, as well as information and training materials addressed to operators and users of on-site domestic wastewater systems (ODWS).This document is applicable to both publicly and privately operated on-site domestic wastewater (blackwater and greywater) systems for one or more dwellings or other premises where wastewater is generated.The scope of this document includes the following:— O&M of ODWS from the operator’s perspective;— O&M of ODWS from the user’s perspective;— training and information aspects;— environmental, health and safety issues.The following are outside the scope of this document:— detailed design of ODWS;— limits of acceptability for discharge of wastewater or sludge;— analytical methods;— management structure of wastewater services’ activities for O&M;— content of contracts or subcontracts.NOTE 1 Management of ODWS, especially in rural areas and areas under development, is sometimes provided by the owners of the premises where wastewater is generated. In such cases, the owners of the premises carry out the management themselves. In this document, the term “services” includes “self-services” provided by the owners or users of the premises.NOTE 2 Especially in undeveloped areas, sanitary wastewater is collected in an undiluted form. Sources of sanitary wastewater in this document are domestic, excluding stormwater runoff.NOTE 3 The designation of activities as operation activities or maintenance activities can differ according to the local context. However, it is important that activities essential for the proper functioning of ODWS are carried out, no matter how these activities are designated.