Effective sanitation relies on the proper treatment of soil and waste water. In situations where there is no access to a mains sewerage system, as in most urban and rural areas of developing countries, it has often been difficult to ensure that waste does not pose health, hygiene and a variety of pollution hazards.
In an initiative to find an environmentally sustainable solution to treating domestic waste water and industrial effluents, the Auroville Centre for Scientific Research (CSR) has been developing decentralised treatment technology for rural, semi-urban and urban situations since 1995. There are currently over 40 natural decentralised waste water treatment systems (DEWATS) operating in Auroville and the surrounding area. The link has a wealth of plans, photos and information. There is an interesting article on the Schauberger Vortex system in 'Auroville Today'.
The development of these systems by CSR has been co-financed by the European Commission via the Bremen Overseas Research & Development Association, Germany (BORDA).