The 4 National Taps
Singapore is a small country with little resources and land, thus it needs to maximise the use of its resources.
In present times, Singapore utilises 2 systems for collecting rainwater and used water. A well linked network of drains, canals, rivers and stormwater and collection ponds is a storage ground for rainwater. Rainwater is then channeled to 17 reservoirs for permanent storage. Singapore is thus known as one of the few countries in the world to utilise urban stormwater for its water supply.
Click on the map below to find out more about the reservoirs!
the 1st national tap
local catchment water
Singapore has been importing water from Johor, Malaysia, under two bilateral agreements. The first agreement expired in August 2011 and the second agreement will expire in 2061.
imported water
the 2nd national tap
NEWater Usage: Industry and Drinking Water
Watch the NEWater treatment process here.
Industry: NEWater is primarily for non-potable industrial uses.
Drinking Water:A small percentage of NEWater is blended with raw water in the reservoir. The raw water from the reservoir then goes through treatment before it is supplied to consumers as tap water. This ensures that NEWater has a similar taste to raw water.
Stringent Processing Procedures
Twice a year, NEWater undergoes rigorous audit processes by international experts in engineering, water chemistry, toxicology and microbiology.
newater
the 3rd national tap
newater production process
1. Microfiltration (MF)
1. Treated used water is passed through membranes.
2. Suspended solids, colloidal particles, disease-causing bacteria, certain viruses and protozoan cysts are retained on the membrane surface.
3. Filtered water that passes through the membrane only contain dissolved salts and organic molecules.
2. Reverse Osmosis (RO)
1. Reverse osmosis uses a semi-permeable membrane, its small pores in allowing smaller molecules like water to pass through.
2. Contaminants like bacteria, viruses, heavy metals, nitrate, chloride, sulphate, disinfection by-products, aromatic hydrocarbons, pesticides, cannot pass through the membrane.
3. The resulting water is free from these contaminants and contains a negligible amount of salts and organic compounds.
At this stage, the water is already of a high grade water quality. The third stage of the NEWater production process is a further safety back-up to the Reverse Osmosis. Here, ultraviolet or UV disinfection ensures that all organisms are inactivated and guarantees purity of the product water.
With the addition of some alkaline chemicals to restore the pH balance, the NEWater is now ready to be piped off to its wide range of applications. NEWater supplies 30% of the nation’s current water needs.
desalination
the 4th national tap
1. Tuaspring Desalination Plant
1. Seawater enters the desalination plant and is channelled through ultrafiltration membranes to remove suspended solids and microorganisms.
2. After this pre-treatment, a two-stage reverse osmosis treatment is conducted, with the seawater passed through semi-permeable membranes, to remove the salt from the water and produce fresh, pure water.
3. This water is then re-mineralised before being delivered to PUB to be distributed to households and industries in Singapore.
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Capacity of 70 Million Gallons of desalinated water per day
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Desalination meets up to 25% of water demand
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Supplies PUB with desalinated water over 25 years
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Uses Hyflux’s Kristal® ultrafiltration membrane technology for pretreatment membrane installations
2. Singspring Desalination Plant
1. In SingSpring desalination plant, seawater goes through a pre-treatment process where suspended particles are removed.
2. The second stage is reverse osmosis; the same technology used in the production of NEWater. The water produced is very pure and is remineralised in the third stage.
3. After treatment, desalinated water is blended with treated water before it is supplied to homes and industries in the western part of Singapore.
Water demand in Singapore is currently about 400 million gallons a day (mgd), with homes consuming 45% and the non-domestic sector taking up the rest.
planning for the future
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