Water supply ops contribute most to greenhouse gas emission: Study

CHENNAI: Among all the operations of a municipal corporation such as waste management and transport, supplying drinking water to denizens is not so sustainable in terms of climate change mitigation, a recent study revealed.

An analysis of Coimbatore, Tiruchy, and Tirunelveli cities revealed that water supply contributes to more than 50 per cent greenhouse gas (GHG) emissions among the municipal operations. According to the report, ‘State of Cities: Towards Low Carbon and Resilient Pathways’ published by the National Institute of Urban Affairs (NIUA) in partnership with International Council for Local Environmental Initiatives (ICLEI) South Asia, in terms of energy consumed through municipal operations in Coimbatore, 43 per cent of total energy consumed by the city corporation is being spent on water supply.

Moreover, the water supply sector contributes to 51 per cent of total GHG emissions through municipal operations.

In total, Coimbatore emits 3.22 million tonnes of carbon dioxide equivalent, of which industries in the city contribute to 33 per cent of the total emissions. The study covered as many as 15 cities in the country. Interestingly, a majority of the 15 cities emit higher GHG for water supply.

Meanwhile, around 64 per cent of total energy consumed by Tirunelveli city corporation is being spent on water supply. Moreover, the water supply sector contributes to 66 per cent of GHG emissions through municipal operations.

In total, Tirunelveli emits 0.66 million tonnes of carbon dioxide equivalent, of which residential buildings in the city contribute to 51 per cent of the total emissions.

As per the report, around 47 per cent of total energy consumed by Tiruchy city corporation is being spent on water supply. Moreover, the water supply sector contributes to 54 per cent of GHG emissions through municipal operations.

In total, Tiruchy emits 1.88 million tonnes of carbon dioxide equivalent of which residential buildings in the city contribute to 33 per cent of the total emissions. The report projects increasing temperature in Tirunelveli and Tiruchy that would lead to extreme weather events such as floods, droughts and storms. Coimbatore will witness increased maximum and minimum daily temperatures with increase in precipitation.

As per earlier studies, the entire chain of processing water contributes to GHG emissions starting from raw water abstraction, treatment and supply of drinking water, collection and treatment of wastewater and final disposal of the treated wastewater and of the resulting sludge. One study estimates around 10kg of carbon emission to supply one cubic metre of drinking water. It may be noted that the Chennai Metropolitan Water Supply and Sewerage Board (Metrowater) supplies around 1,000 million litres of water every day, which is 10 lakh cubic metres.