Introduction – In addition to underground drainage and large‐scale sewage treatment plants (STPs) and the management of faecal sludge and septage from non‐sewered on‐site systems, small‐scale sanitation (SSS) systems are becoming increasingly important. Such systems consist of small‐scale sewerage networks and STPs, allowing for incremental, modular and flexible implementation. Therefore, they have significant potential for cost‐effective local wastewater treatment and reuse. In order to improve public health, relieve water stress and protect the environment in urban India, SSS systems have a key role to play.
Since a policy drive for small sewage treatment plants (SSTPs) in India beginning in 2006, there has been a remarkable growth in the number of installations in the country’s rapidly expanding urban areas, especially in big cities. However, it is known that many of the existing systems are underperforming or have failed for various reasons.
Thus far, SSS sector developments in India have not been informed by a systematic assessment of lessons learned, and there has been very little research on the enabling conditions and implications for the successful long‐term operation and management of SSS systems at scale. The main goal of the "Technology, Implementation and Operation" component of the 4S Project is to evaluate present experience with SSS systems and to develop evidence‐based policy recommendations for their successful design, implementation, operation and maintenance at scale.