A major threat of the untreated sewage and wastewater is to rivers and other water bodies. As per Census 2011, India has sewer systems linked to 32.7 per cent of urban households. The rest depend on onsite sanitation systems like septic tanks or public toilets. There is still a major section of the population in urban areas who defecate in the open. This is more in the slums that now comprise almost fifty per cent of the urban areas. Scant facilities of sewage treatment clubbed with unscientific disposal of septage pose a major challenge to the water systems and public health.
Given the constraints involved in centralised systems, it is wiser to popularise and promote the Decentralised Wastewater Treatment Systems (DEWATS) approach. DEWATS has been hailed as a cost-effective and more successful approach that promotes people-centric waste to resource activities. As compared to centralised systems that are high on economic costs and require skilled manpower, decentralised systems can be promoted by involving local people and with low cost. It is important to note the system operates in a natural system, considering local conditions.
It uses a natural-three-step bio-remediation process. The first three chambers, which include the Screen Chamber (1.0 molecular weight (mw) + 1.1 millilitre (ml) + 1 metric ton (mt.) Deep), Pre-process filter Chamber (2.0 mw + 2.5 ml + 2.5 mt Deep), Baffled Septic Tank (2.0 mw + 7.5 ml + 3.0 mt Deep), are used for the sedimentation of the sludge, preparing the wastewater for filtration. The next chamber is Baffled Filter Reactor Chamber (2.0 mw + 22.0 ml + 2.5 mt Deep) that is filled with stone. This chamber accomplishes the filtration of the water. The last chamber is the Root Zone Treatment Chamber (2.0 mw + 22.0 ml + 2. 0 mt Deep), which is planted with Canna- the root of these plants treat the waste water.