Policy and technology recommendations for scaling up of onsite greywater reuse in Chennai

The water situation is serious in India, where nearly one fifth of the world population is settling having access to only less than one twentieth of the world’s freshwater resources. The expected growth in population will further aggravate water problems. Chennai, a metropolitan city in the south is facing a dire situation of water stress which could worsen in the coming years. The droughts and floods that visit Chennai are a consequence of the rapid urbanization and mismanagement of water. The governance system and the policies with respect to water and sanitation are prevalent but implementation is far from reality. Water is a finite resource that can drive every aspect of human existence, in particular the economy. Conventional linear economy taps the natural resource, produces and disposes waste byproducts to the environment to achieve economic development. Circular economy is in contrast to the conventional linear economy, where the use of natural resources is governed by ecological laws and its recurring utilization at the maximum extent to achieve economic development with the objectives of ‘reducing resource use, reusing and recycling’ natural resources like water. This paper will address the water stress problem by suggesting policy recommendations and technologies that can promote a circular economy of the water resource in the urban environment. Scaling up of onsite greywater reuse will be discussed as a policy in terms of implementation of the same locally in Chennai for the existing and new buildings. Appropriate nature based treatment technologies for treating the greywater will also be reviewed with respect to their ease of implementation. As a result of this study, onsite grey water treatment and reuse will be recommended for its treatability, ease of maintenance, affordability and its benefits.