chennai clean water is always a cause of concern and residents have started making their own efforts to purify water a number of housing projects in chennai are installing centralised reverse osmosis plants for pure water some industries and software companies have started using membrane bio reactor mbr technology to purify waste water and use it for nonpotable purposessince the past few years many homes have had desktop reverse osmosis purifiers but they lead to a huge loss of water for getting 10 litres of water one has to pour 100 litres into the purifier but in a centralised reverse osmosis plant the water saving is 90 said h subramaniam chief operating officer of everything about waterbesides the cost of the equipment is less a 1000 litre plant costs rs four lakh while one purifier alone costs rs 10000 said subramaniamwith the water demand in chennai expected to shoot up to 2248 million litres per day mld by 2026 and rapid depletion of groundwater the city has to find ways to make the best use of available water experts say that if sewage is treated using mbr technology it can be used for nonpotable purposes like gardening if the waste water is allowed to flow through the membrane it gets purified if it is then let through a reverse osmosis plant it becomes potable said subramaniamaccording to deepa sathiaram executive director of en3 green building consultancy many industries and it companies have started adopting such technologies for waste water treatment another issue that is troubling the water sector is the heavy loss due to the leakage theft and unmetered connections according to an asian development bank study the water wastage in chennai mumbai and new delhi is 40 in bangalore it is just 20 said subramaniam there is lot of technology to detect the loss and rectify it the government officials need to be made aware of this he said