Under colonial rule, tanks were the only source of water in Mumbai. Many localities have been named after them. The BMC supplies potable water to the city from six lakes, most of which comes from the Tulsi and Vihar lakes.The Tansa lake supplies water to the western suburbs and parts of the island city along the Western Railway. The water is filtered at Bhandup, which is Asia's largest water filtration plant. India's first underground water tunnel is being built in Mumbai.
About 700 million litres of water, out of a daily supply of 3500 million litres, is lost by way of water thefts, illegal connections and leakages, per day in Mumbai. Almost all of Mumbai's daily refuse of 7,800 metric tonnes, of which 40 metric tonnes is plastic waste, is transported to dumping grounds in Gorai in the northwest, Mulund in the northeast, and Deonar in the east. Sewage treatment is carried out at Worli and Bandra, and disposed off by two independent marine outfalls of 3.4 km (2.11 mi) and 3.7 km (2.30 mi) at Bandra and Worli respectively.
Electricity is distributed by Brihanmumbai Electric Supply and Transport (BEST) in the island city, and by Reliance Energy, Tata Power, and Mahavitaran (Maharashtra State Electricity Distribution Co. Ltd) in the suburbs. Consumption of electricity is growing faster than production capacity. The largest telephone service provider is the state-owned MTNL, which held a monopoly over fixed line and cellular services up until 2000, and provides fixed line as well as mobile WLL services.
Cell phone coverage is extensive, and the main service providers are Vodafone Essar, Airtel, MTNL, Loop Mobile, Reliance Communications, Idea Cellular and Tata Indicom. BothGSM and CDMA services are available in the city. MTNL and Airtel also provide broadband internet service.