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Desalinated Water

The 4th National Tap

Currently, we have five desalination plants.


As Singapore is surrounded by sea, PUB has turned seawater into drinking water. And we continue to invest in research and technology to find more efficient ways to desalinate seawater 

Currently, we have three desalination plants with a combined capacity of 130 mgd that can meet up to 30% of Singapore’s current water demand. Two more desalination plants will be ready by 2020.

Desalinated water is expected to meet up to 30% of Singapore’s future water needs by 2060.  

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The 1st Desalination Plant

In September 2005, Singapore turned on its Fourth National Tap - Desalinated Water, with the opening of the SingSpring Desalination Plant in Tuas. A wholly owned subsidiary of Hyflux, SingSpring won a bid to construct a desalination plant under PUB’s design, build, own and operate (DBOO) model. This plant with a daily capacity of up to 30 million gallons (130,000 m3) of water supplies PUB with desalination water over a 20-year period. 

SingSpring Desalination Treatment

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SingSpring Desalination Plant Treatment Process 

The 2nd Desalination Plant

With a daily capacity of up to 70 million gallons (or 318,500 m3 ) of water, Tuaspring Desalination Plant supplies PUB with desalinated water over a 25-year period.  

Tuaspring Desalination Treatment

View enlarged version >>Tuas Spring Desalination Plant Treatment Process

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)
The ultra-filtration membranes remove impurities, microorganisms and bacteria in water, which can foul the downstream reverse osmosis system.

Part 3: Reverse Osmosis
Reverse osmosis is a critical step in the desalination of seawater. After removal of impurities and suspended particles, water is pumped through the semi-permeable membranes at high pressure. Only water molecules can pass through the membranes at this stage.

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

PM Lee at Tuas Spring Desalination Plant Opening
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.

For latest information on Tuaspring Desalination Plant. Please click here.

The 3rd Desalination Plant

Tuas Desaliantion Plant is the first in Singapore to use advanced pre-treatment technology, a combination of dissolved air-flotation and ultrafiltration. The desalination plant is also fitted with solar panels, with more than half of the total roof area covered by solar panels.


This is the first desalination plant to be owned and operated by PUB. Download brochure for more information about Tuas Desalination Plant [PDF]. 

Tuas Desalination Plant Treatment 

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Tuas Desalination
TDP Opening
From left: HSL Constructor Pte Ltd CEO Mr Charles Quek, Permanent Secretary (MEWR) Mr Albert Chua, Minister for the Environment and Water Resources (MEWR) Mr Masagos Zulkifli and PUB Chief Executive Mr Ng Joo Hee officiating the launch of TDP on 28 June 2018. 

Making Desalination More Energy-efficient

Desalination is an energy-intensive water source. Singapore currently uses reverse osmosis for its desalination, which uses about 3.5kWh/m3 of energy to make seawater drinkable. This process produces pure drinking water by pushing seawater through membranes to remove dissolved salts and minerals.

PUB is constantly exploring ways to reduce the energy required to ensure the sustainability of desalinated water. PUB's goal is to reduce the energy requirement for desalination by more than halve from the current 3.5kWh/m3 to 1.5 kWh/m3 and then to 1 kWh/m3 in the long run.


Electro-deionisation is a method that uses an electric field to pull dissolved salts from water. An achievable energy consumption of 1.65 kWh/m3 has been demonstrated at a pilot plant. This is less than half the energy required by conventional seawater reverse osmosis process.

PUB has plans to scale up this technology and demonstrate it at a facility in Tuas. We will also be validating this technology at Tuas Desalination Plant.


Besides electro-deionisation, PUB is also exploring biomimicry. This desalination method involves mimicking biological processes by which mangrove plants and euryhaline fish extract freshwater from seawater using small amount of energy.

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