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Water Supply

Then and Now

The Early Years

The earliest sources of water on the island were inland streams and wells. These were small sources, sufficient for the few inhabitants on the island. After its founding in 1819, as Singapore grew as a port city, a small reservoir was constructed at Fort Canning in 1822 to supply water to ships which called at the port. By 1850, the island’s population had grown to more than 50,000 without provisions made to supply these residents with water. Planning for Singapore’s water supply became an issue. It was only in 1857 that philanthropist Tan Kim Seng made a donation of S$13,000 for the building of Singapore’s first waterworks and piped water supply. This provided the impetus for the construction of an impounding reservoir in Thomson Road in 1868. It was expanded in 1891 and named MacRitchie Reservoir in 1922, after Municipal Engineer James MacRitchie who oversaw the expansion.

As colonial Singapore’s population grew, steps were taken to enlarge and improve the water supply. In 1910, the Singapore Municipality built the Kallang River Reservoir, which was later renamed Peirce Reservoir in 1922, after Municipal Engineer Robert Peirce who was in charge of its construction. Seletar Reservoir, the third impounding reservoir, was named after a Malay word that refers to coastal dwellers called Orang Seletar, and was built within the central catchment in 1920 and later expanded in 1940.

These were, in a nutshell, the main water sources in Singapore at the time of PUB’s formation in 1963.


Over the years, through strategic planning and investment in research and technology, PUB has built a robust and diversified supply of water known as the ‘Four National Taps’. The water supply comprises (1) local catchment water, (2) imported water, (3) highly-purified reclaimed water known as NEWater, and (4) desalinated water.

Local Catchment Water

As a small island that doesn't have natural aquifers and lakes and with little land to collect rainwater, Singapore needs to maximise whatever it can harvest.

Currently, Singapore uses two separate systems to collect rainwater and used water. Rainwater is collected through a comprehensive network of drains, canals, rivers and stormwater collection ponds before it is channelled to Singapore's 17 reservoirs for storage. This makes Singapore one of the few countries in the world to harvest urban stormwater on a large scale for its water supply.

The newest reservoirs are Punggol and Serangoon Reservoirs which are our 16th and 17th reservoirs. By 2011, the water catchment area has increased from half to two-thirds of Singapore’s land surface with the completion of the Marina, Punggol and Serangoon reservoirs.

With all the major estuaries already dammed to create reservoirs, PUB aims to harness water from the remaining streams and rivulets near the shoreline using technology that can treat water of varying salinity. This will boost Singapore’s water catchment area to 90% by 2060.


Imported water

Singapore has been importing water from Johor, Malaysia, under two bilateral agreements. The first agreement expired in August 2011 and second agreement will expire in 2061.



Singapore success story and the pillar of Singapore’s water sustainability, NEWater is high-grade reclaimed water. It is produced from treated used water that is further purified using advanced membrane technologies and ultra-violet disinfection, making it ultra-clean and safe to drink.

NEWater has passed more than 100,000 scientific tests and surpasses World Health Organisation requirements, a testimony of its high quality and reliability.

NEWater is proof that using today's water treatment technologies, water of any quality can be treated into drinking water. It has put Singapore on the world map for innovative water management, including winning for PUB the Stockholm Industry Water Award in 2007. The first NEWater plants were opened in Bedok and Kranji in 2003. The latest and largest NEWater plant at Changi with a capacity of 50mgd was opened in May 2010. Currently, NEWater meets up to 30% of the nation’s current water needs. By 2060, we plan to triple the current NEWater capacity so that NEWater can meet up to 55% of our future water demand.

NEWater Usage: Industry and Drinking Water


NEWater is primarily for non-potable industrial uses. Supplied to wafer fabrication, electronics and power generation industries for process use, it is also piped to commercial and institutional buildings for air conditioning cooling purposes. This frees up potable water for domestic consumption. It is delivered via a separate distribution network to industrial and commercial customers.

The demand for NEWater has grown 15-fold from 4 mgd (18,200 cubic metres a day) in 2003 to some 60 mgd (273,000 cubic metres a day) today.

Drinking Water

A small percentage of NEWater is also blended with raw water in the reservoir. The raw water from the reservoir then goes through treatment at the waterworks before it is supplied to consumers as tap water.


Desalinated Water

In September 2005, Singapore turned on its fourth National Tap, desalinated water, with the opening of the SingSpring Desalination Plant in Tuas. The SingSpring desalination plant was PUB’s first public-private partnership (PPP) project, where SingSpring Pte Ltd was appointed to design, build, own and operate the plant and supply water to PUB. This plant can produce 30 million gallons of water a day (136, 000 cubic meters) and is one of the region’s largest seawater reverse-osmosis plants.

At the SingSpring desalination plant, sea water goes through a pre-treatment process where suspended particles are removed. In the second stage, the water undergoes reverse osmosis (RO). This is the same technology used in the production of NEWater. The water produced is very pure and is remineralised in the third stage. After treatment, desalinated water is blended with treated water before it is supplied to homes and industries in the western part of Singapore.

A second and larger desalination plant with a capacity of 70 million or 318,500 cubic metres of desalinated water per day, the Tuaspring Desalination Plant marks another major step in Singapore’s journey towards water sustainability. Today, desalinated water can meet up to 25% of Singapore’s current water demand.

Click here for more details.

The plan is to grow Singapore’s desalination capacity, so that the Fourth National Tap will be able to meet up to 25% of our future water demand by 2060.

Last updated on 30 May 2014