Techno-economic analysis of sustainable water management techniques - a case study of residential township in India

Technically efficient and economically viable methods of rooftop rainwater harvesting, greywater recycling and use of low flow devices for integrating in residential townships are identified. An integrated tool is developed for generating designs of identified techniques along with the estimates of capital costs required for installation and the total net present cost. It also calculates potential of water saving. A case study of a residential township in Nagpur, India has been presented. Unit cost and current net value of water using these techniques are calculated. Unit costs of water per cubic meter using rainwater harvesting, low flow devices and greywater recycling are found to be INR 230 (1USD = INR 55), INR 38 and INR 124 respectively. The current net value of water saved using rainwater harvesting; low flow devices and greywater recycling are INR 388,080 INR 162,437 and INR 70,560. Total cost of installation of these three techniques for the case study of residential township is INR 19,813,866, i.e., only 1.14% of the total cost of the project. This study enables prioritisation of practicing rainwater harvesting, use of low flow devices and greywater recycling for conservation of water as well as evaluation and allocation of the percentage of land area required for these techniques.