New housing to reuse water

By Rajil Menon
Published: Tuesday 30 June 2009

Mumbai municipality readies norms for wastewater from kitchens

future housing projects in Mumbai would need to have grey water recycling plants to treat wastewater from kitchen, washing clothes and bathing. The treated water is to be used for horticulture and other non-drinking purposes. The Municipal Corporation of Greater Mumbai drafted guidelines that would mandate developers to install such recycling plants in housing projects with over 1,858 sq metres built-up area.

Potential water savings

  • 3,400 mld Total water supply
  • 2,720 mld wastewater discharged
  • 1,360 mld grey water component
  • 1,000 mld recyclable grey water
"The guidelines will be incorporated in the building bye-laws once it gets approved by the corporation's apex policy making body," an official said. The Corporation officials said 40-50 per cent of the wastewater discharged by households is grey water and 80 per cent can be reused. "If housing colonies in Mumbai adopt this practice, there will be no shortage of drinking water in the city," he said.As per the proposal, the builder will bear the cost of setting up such recycling plants.

Companies that offer such water treatment services said grey water collection in existing buildings is not feasible as sewage and grey water have common tanks. "Installing grey water recycling plants in new projects would not be costly," said Arshad Moolji of Mumbai-based firm A M Ozonics. Grey water is made fit for reuse by first filtering it and then treating it with ozone to kill bacteria. This also removes odour and colour from wastewater. Moolji said the electricity consumed in operating a recycling plant is low--2 kilowatt per hour--and is offset by the water saved. Some housing colonies in Thane and Worli have such recycling plants.

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