and 2060. demand are to keep up with this increase. by the mid-21st century, water demand is expected to be met by reclaimed water at the tune of 50% and by desalination accounting for 30%, compared to only 20% supplied by internal catchments. in response, the government especially since the 2010s has constructed multiple desalination plants throughout the country to keep up with the demand. these include the tuas south desalination plant, tuas desalination plant, the keppel marina east desalination plant and the jurong island desalination plant, which began operations in 2013, 2018, 2020 and 2022 respectively. a punggol desalination plant is also currently under construction. water sources and integrated management the water resources of singapore are especially precious given the small amount of densely settled land. singapore receives an average of 2,400 mm of rainfall annually, well above the global average of 1,050 mm. the constraint is the limited land area to catch and store the rainfall, and the absence of natural aquifers and lakes. therefore, singapore relies on four water sources, called the "four national taps": rainfall, collected in artificial reservoirs that collect water from carefully managed catchment areas (200–300 million gallons per day, depending on rainfall), imported water (up to 250 million imperial gallons (1,100,000 m3) per day, according to the 99-year agreement signed in 1962, plus an additional quantity under the 1990 agreement), reclaimed water (producing what is called newater) (up to 115 million imperial gallons (520,000 m3) per day, officially only "30% of demand"), and seawater desalination (up to 50 million imperial gallons (230,000 m3) per day, officially only "10% of demand"). this "four tap" strategy aims to reduce reliance on foreign water supply by increasing the volume supplied from the three other sources, or "national taps". since water demand in 2011 was 380 million imperial gallons (1,700,000 m3) per day, singapore could actually already have been water self-sufficient in 2011 except in years of very low rainfall. the official figures downplay the share of reclaimed and desalinated water in water supply, and thus the ability of the country to be self-sufficient. however, the chairman of pub admitted in 2012 that water self-sufficiency could be achieved well before the target year of 2061. in singapore, water management is closely integrated with land management. the latter is tightly controlled in order to prevent any pollution of water resources through sewage, sullage or other sources of pollution. the management of water supply, sanitation and stormwater drainage is managed by a single agency, the public utilities board, in an integrated and coordinated manner. water from catchment areas the marina barrage. two thirds of the country's surface area are classified as partly protected catchment areas with certain restrictions on land use, so that the rainwater can be collected and used as drinking water. as of 2012, surface water was collected in 17 raw water reservoirs. singapore's oldest reservoirs - macritchie, lower peirce, upper selatar as well as the more recently built upper peirce reservoir - are all located in the central catchment nature reserve, a protected area that has been reforested to protect the water resources and act as a "green lung" for the city. the larger reservoirs, however, have been built after independence and are located in river estuaries that have been closed off by barrages. reservoir water is treated through chemical coagulation, rapid gravity filtration and disinfection. imported water singapore's imported water comes through a pipeline that runs along a 1 km bridge, the johor–singapore causeway, that also carries a road and a railway. imported water has gradually reduced over the years; as of 2009, imported water had been reduced from 50% previously to 40% of total consumption. after the expiry of a 1961 water agreement between malaysia and singapore in 2011, two agreements are in force now. one was signed in 1962 and another one in 1990. both will expire in 2061. under the first agreement the price of raw water was set at 3 malaysian sen per 1,000 imperial gallons (4,500 l), corresponding to about 0,2 us cents per cubic meter. under this agreement singapore is entitled to receive up to 250 million imperial gallons (1,100,000 m3) per day, corresponding to 56% of its water use of 380 million imperial gallons (1,700,000 m3) in 2011. furthermore, under the 1990 agreement, singapore is entitled to buy an additional unspecified quantity of treated water from the linggiu dam at a price that is higher than under the previous agreement. reclaimed water main article: newater bottles of newater for distribution during the national day parade celebrations of 2005 at marina south. in singapore, reclaimed water is branded as newater and is bottled directly from an advanced water purification facility for educational and celebratory purposes. though most of the reused water is used for high-tech industry in singapore, a small amount is returned to reservoirs for drinking water. newater is the brand name given to ultra-pure water that is produced from reclaimed water. wastewater, which is called "used water" in singapore, is treated in conventional advanced wastewater treatment plants that are called reclamation plants in singapore. the effluent from the reclamation plants is either discharged into the sea or undergoes further microfiltration, reverse osmosis and ultraviolet treatment. reclaimed water provides 40% of singapore's water requirements. using the newater technology, cleaned water is recycled to create ultra-clean, premium reclaimed water. up to 55% of singapore's water demand is anticipated to be satisfied by newater by 2060. the quality of newater is monitored by, among others, an international panel of experts and exceeds the world health organization (who) standards for drinking water, much higher than imported water. in 2012, there were four newater factories, located at the bedok, kranji, ulu pandan and changi next to five water reclamation plants. at the end of 2002, the programme had garnered a 98 percent acceptance rate among singaporeans, with 82% of respondents indicating that they would drink the reused water directly, another 16% only when mixed with reservoir water. the produced newater after stabilization (addition of alkaline chemicals) is in compliance with the who requirements and can be piped off to its wide range of applications (e.g. reuse in industry, discharge to a drinking water reservoir). newater now makes up around 30% of singapore's total use, by 2060 singapore's national water agency plans to triple the current newater capacity as to meet 50% of singapore's future water demand. most of the newater is used by industries for non-potable uses such as wafer fabrication. the rest is fed into nearby reservoirs. as of 2019, according to pub, newater was able to meet 40% of singapore's water requirements. the high purity of the water has actually allowed industries to reduce their costs. with the construction of the deep tunnel sewerage system the decentralized water reclamation plants and newater factories are expected to be gradually closed and replaced by the single, much larger water reclamation plant and newater factory at changi at the eastern end of singapore island. the bedok reclamation plant was the first one to be decommissioned in 2009, followed by the seletar plant in 2011. the bedok newater plant, however, continued to operate, while the seletar newater plant was decommissioned along with the reclamation plant. the kranji, ulu pandan and bedok reclamation plants had been upgraded in 1999-2001, making them more compact so that they needed less land and covering them for odor control in order to make nearby land more valuable. desalinated seawater on 13 september 2005, the country opened its first desalination plant, singspring desalination plant, in tuas at the southwestern tip of singapore island. the s$200 million plant, built and operated by hyflux, can produce 30 million imperial gallons (140,000 m3) of water each day and meets 10% of the country's water needs. in 2007, the sungei tampines was established as a test project for future large-scale desalination projects. this project would influence further desalination projects in the country, as the reliability of the dual-purpose desalination concept was tested on a smaller scale. that facility, which also draws freshwater and seawater from surrounding sources, is able to produce around one million gallons a day. the bid to build and operate singapore's second and largest desalination plant, tuaspring desalination plant (since renamed tuas south desalination plant), with a capacity of 70 million imperial gallons (320,000 m3) per day, also located at tuas, was launched in june 2010. hyflux won the contract in april 2011, and the plant began operations two years later in 2013. in may 2019, following financial losses from the plant, pub took over the tuaspring desalination plant. in june 2018, a third desalination plant, the tuas desalination plant (tdp), was opened. functioning also as a test bed for energy saving technology, the plant can produce 30 million imperial gallons (140,000 m3) of water per day. together, desalinated water from singspring, tuaspring and the tuas desalination plants can meet up to 30% of singapore's current water needs as of 2019. in 2019, government has identified five other coastal sites for future plants in the coming decades, with the objective of bringing the installed capacity to one million m³ per day, so that desalination will be able to meet up to 30% of singapore's future water demand by 2060. in june 2020, singapore began operating its fourth desalination plant, the keppel marina east desalination plant (kmedp). in april 2022, a fifth desalination plant began operations, the jurong island desalination plant (jidp). plant namedate of commissioningmaximum capacity (ml/day)operator singspring desalination plant2005137keppel tuaspring (renamed tuas south desalination plant; tsdp)2013320pub tuas desalination plant (tdp) 2018137pub keppel marina east desalination plant (kmedp) 2020137keppel jurong island desalination plant (jidp)2022137tuas power–singapore technologies marine (tp–stm) consortium water research and technology sanitation until 2010, wastewater in singapore was collected through a sewer system that included 139 pumping stations that pumped water to six wastewater treatment plants. these pumping stations and plants were gradually decommissioned while a newer system, the deep tunnel sewerage system (dtss) was made operational. the changi water reclamation plant, the heart of the first phase of the dtss, was opened by prime minister lee hsien loong in june 2009. the first phase of the dtss consists of a 48-km long deep tunnel sewer that runs 20 to 55 metres below ground, and channels used water to the changi water reclamation plant at the eastern end of the island. the plant had an initial capacity of 176 million imperial gallons (800,000 m3) per day. most of the treated used water is discharged into the sea through an outfall, while some of it is further purified into newater. the deep tunnel works entirely by gravity, eliminating the need for pumping stations, and thus the risks of used water overflows. at one-third the size of conventional plants, the changi water reclamation plant is designed to be compact. centralisation of used water treatment at changi also allows for economies of scale. in a second phase of the dtss, the deep tunnel system is to be expanded to the entire island, with a second wastewater treatment plant at tuas at the western end of the island. stormwater management the stormwater drainage system in singapore is completely separated from the sewer system. it consists of 7,000 km of public roadside drains and about 1,000 km of major canals and waterways that are regularly cleaned of debris and maintained by private companies under performance-based contracts with pub. this system has reduced the flood-prone area from 3,200 hectares in the 1970s to about 49 hectares today despite increased urbanization, which usually would have resulted in more floods. pub plans to further reduce flood prone areas to 40 hectares by 2013. in the 1960s and 1970s widespread flooding was common in singapore, especially in the city centre, which is built on relatively low-lying land. nevertheless, flash floods caused by unusually heavy rains and blocked drains caused damage in 2010 and 2011. water use, conservation and efficiency there have also been campaigns to urge people to conserve water, reducing consumption from 165 litres per person per day in 2003 to 155 litres in 2009. the target is to lower it to 140 litres by 2030. public education was an important instrument to promote water conservation. for example, a water efficiency labeling scheme for taps, showerheads, toilets and washing machines was introduced so that consumers