power, health and community services and real estate are also important to the city's economy. Delhi has one of India's largest and fastest growing retail industries. Manufacturing also grew considerably as consumer goods companies established manufacturing units and headquarters in the city. Delhi's large consumer market and the availability of skilled labour has also attracted foreign investment. In 2001, the manufacturing sector employed 1,440,000 workers and the city had 129,000 industrial units. Utility services Delhi's municipal water supply is managed by the Delhi Jal Board (DJB). , it supplied 650 million gallons per day (MGD), whereas the estimated consumption requirement is 963 MGD. The shortfall is met by private and public tube wells and hand pumps. At 240 MGD, the Bhakra storage is DJB's largest water source, followed by the Yamuna and Ganges rivers. Delhi's groundwater level is falling and its population density is increasing, so residents often encounter acute water shortage. Research on Delhi suggests that up to half of the city's water use is unofficial groundwater.In Delhi, daily domestic solid waste production is 8000 tonnes which is dumped at three landfill locations by MCD. The daily domestic waste water production is 470 MGD and industrial waste water is 70 MGD. A large portion of the sewage flows untreated into the Yamuna river. The city's electricity consumption is about 1,265 kWh per capita but the actual demand is higher. In Delhi power distribution is managed by TPDDL and BSES Yamuna & BSES Rajdhani since 2002. The Delhi Fire Service runs 43 fire stations that attend about 15,000 fire and rescue calls per year. The state-owned BSNL and private enterprises such as Airtel, Vi, Jio, and provide telephone and cell phone services to the city. Cellular coverage is available in GSM, CDMA, 3G, 4G and 4G+. Transport Air Indira Gandhi International Airport, situated to the south-west of Delhi, is the main gateway for the city's domestic and international civilian air traffic. In 2015–16, the airport handled more than 48 million passengers, making it the busiest airport in India and South Asia. Terminal 3, which cost to construct between 2007 and 2010, handles an additional 37 million passengers annually. In 2010, IGIA was conferred the 4th best airport award in the world in the 15–25 million category, by Airports Council International. The airport was rated as the Best airport in the world in the 25–40 million passengers category in 2015, by