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Desalinated Water

The 4th National Tap

SingSpring Desalination Plant

In September 2005, Singapore turned on its fourth National Tap - desalinated water, with the opening of the SingSpring Desalination Plant in Tuas. It was PUB’s first public-private partnership (PPP) project. SingSpring Pte Ltd was appointed to design, build, own and operate the plant and supply water to PUB. One of the region’s largest seawater reverse-osmosis plants, this plant can produce 30 million gallons of water (130,000 m3) a day. 

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

Tuaspring Desalination Plant

Tuaspring Desalination Plant is the second and larger desalination plant with a capacity of 70 million gallons or 318,500 m3 of desalinated water per day. 

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Part 1: Intake Screening
As seawater flows into the plant, sediments like seaweed and other large debris are removed via mechanical screens. Chlorine is added to hamper marine growth in pipes and other structures in the system.

Part 2: Pre-treatment (Ultrafiltration)
In the pre-treatment stage, The water goes through ultrafiltration membranes to remove impurities, microorganisms and bacteria which can foul the downstream reverse osmosis system.

Part 3: Reverse Osmosis
Reverse osmosis is a critical step in the desalination of sea water. After impurities and suspended particles are removed, the water is pumped at high pressure through semi-permeable membranes which only allows water molecules to pass through.

Finally, after reverse osmosis, the water is re-mineralised and stored in PUB's service reservoir before it is distributed to homes.

Prime Minister Lee Hsien Loong officially opens Tuaspring Desalination Plant, Singapore's second and largest desalination plant From left: Permanent Secretary (MEWR) Choi Shing Kwok, PUB Chairman Tan Gee Paw, Minister for the Environment and Water Resources Vivian Balakrishnan, Prime Minister Lee Hsien Loong, 2nd Minister for the Environment and Water Resources Grace Fu, PUB Chief Executive Chew Men Leong, and Hyflux Executive Chairman and Group CEO Olivia Lum.

Looking Ahead
There are currently two desalination plants in Singapore with a combined capacity of 100 mgd and this can meet up to 25% of Singapore’s current water demand. The third desalination plant is expected to be completed in Tuas by 2017, and the fourth in Marina East by 2020. Desalinated water is expected to meet up to 30% of Singapore’s future water needs by 2060.  

Low-energy Desalination

Singapore currently uses reverse osmosis for its desalination, which uses 3.5kWh/m3. This process produces pure drinking water by pushing seawater through membranes to remove dissolved salts and minerals. Moving ahead, we are looking at exploring low-energy desalination to ensure the sustainability of Desalinated Water. PUB's goal is to halve the desalination energy used in the future.


Electro-deionisation is a method that uses a electric field to pull dissolved salts from water. Plans are put in place to scale up the technology and demonstrate it at a 38,000m3/day facility in Tuas.  


The mimicking of biological processes by which mangrove plants and euryhaline fish extract freshwater from seawater using small amount of energy.