water meter
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In India, Calcutta’s water meter pilot project has shown that the average resident uses up to four times the national consumption benchmark, indicating large scale wastage of the resource.

The project saw approximately 1,000 houses across north Calcutta receive a smart water meter.

National per capita consumption, calculated by the Central Public Health and Environmental Engineering Organisation, is estimated at 135 litres a day. However, civic officials have found that houses with smart meters have a daily per capita consumption of  between 600 and 800 litres per day.

Engineers were aware of the wastage problem however, previously suspected a +- 300 litre benchmark, clearly underestimating the situation.

Water consumption data was studied in neighbourhoods like Paikpara and Belgachhia, where the 1000 meter installations took place. Meter readings were taken every seven days and divided by the number of household residents, to gain the most accurate per capita consumption.

Hydrology expert Kalyan Rudra, who is also the chairman of the state pollution control board, called water wastage "ethically wrong," further stating that the Hooghly couldn't be relied upon for a never-ending supply.

"The western tributaries of the Hooghly have already dried up. At this time of the year, the river's source of replenishment is mostly tidal water. This itself is an alarming situation. We shouldn't think that we can waste this resource."

Only about 400 buildings currently pay the municipal corporation for treated water based on consumption.

Trinamul leader Subrata Mukherjee had proposed to introduce water tax when he was the mayor of Calcutta between 2000 and 2005, but Mamata Banerjee did not allow that to happen.

The national consumption benchmark of 135 litres is based on a two-part assessment of the daily water needs of a person. "Ninety litres a day are used in the toilet and to wash clothes and utensils. Another 45 litres are required for drinking, bathing and cooking," said Ashok Tawadia, chief engineer of the Brihanmumbai Municipal Corporation's water supply department.

State officials have said that the only way to reduce waste is to charge consumers for water use.

Officials and engineers of municipal corporations in Mumbai and water boards in Chennai, Bangalore and Delhi told Metro that residents have to pay for water in all these cities. The tariff rises with increase in consumption beyond slabs.