Centralised and Decentralised Wastewater Management

The Specialist Group on Sanitation and Water Management in Developing Countries has started to engage intensively with the topic of decentralised versus centralised sanitation and wastewater management systems with a focus on developing countries.

Overall, the task group aims at removing prejudices against or for centralised and decentralised systems and tries to illustrate at selected case studies the advantages and disadvantages of both types of systems. In addition the task group aims at reviewing and providing tools that can help to compare both systems and take informed decisions on which system is more suitable in a specific context.

This task force has the following specific objectives:

Identify practical definitions of decentralised and centralised options

1. Review existing case studies where decentralised and centralized technologies have successfully or not so successfully (“failure cases”) been implemented in developing countries and compile “lessons learned”. Initially this will focus on (more) decentralised and (more) centralised case studies. The review will aim at identifying the factors that led either to success or failure from an integrated perspective (including also institutional, economic, financial, etc. aspects). At the start of this work the task group members will agree on a rough evaluation framework. It will basically encompass those aspects mentioned in section 1. This first list will then be complemented by aspects/criteria that are relevant for the local context in each case study. At the start the approach will be tested in 2-3 case studies.

At a later stage this task may be expanded to review case studies where specific technologies have been applied (optional).

2. Documentation of case studies. The information collected in each case study will be documented in the form of fact sheets.

3. Identify global criteria for measuring the sustainability of sanitation and wastewater management systems in developing countries. Several approaches exist and have been applied and this objective pursues to identify suitable elements and propose an approach that could become an “IWA Standard” for sustainability assessment of wastewater management systems, in particular in the context of decentralised versus centralised solutions. The experiences from the review and documentation of case studies (objective 1 and 2) will help to define a suitable standard for assessing the sustainability of centralized and decentralized wastewater management systems.

4. Develop recommendations and guidelines that result form the work under objective 1,2 and 3 with respect to sanitation and wastewater planning in developing countries.