Discharge of untreated sewage is single most important cause for pollution of surface & ground water since there is a large gap between generation and treatment of domestic wastewater in India. The problem is not only of adequacy of treatment capacity but also operation and maintenance of treatment plants. Several sewage treatment plants are established under centrally funded National River Action Plan. However, their operation and maintenance is generally not satisfactory. If massive investment is done on establishing sewage treatment plants and not properly operated, the entire exercise becomes futile. In order to ensure that these STPs function properly, it was felt necessary to carry out study to evaluate their performance and identify main problems both technical and administrative to remedy the situation. CPCB with the help of a consultant initiated a detailed study of the STPs in India. The study includes individual plant visit, discussion with operating staff, evaluating technological aspects & management aspects to bring out the major cause of poor performance.