The Ministry of Urban Development, Government of India, had funded the setting up of a Centre of Excellence in the area of Decentralized Wastewater Management, in the Department of Civil Engineering at IIT Madras in the year 2009. The scope of the project included: preparation of detailed implementation plan in identified cities in case of decentralized wastewater management, helping the ULBs in the implementation of the plan for decentralized wastewater management plan, and documentation and dissemination of the concepts and findings. A manual on the Decentralized Wastewater Management system, dealing with all aspects, has been prepared. The purpose of this capsule guideline is to provide the decision makers with an essence on various aspects of decentralized wastewater management.