How is an under-sink water filter installed in a Singapore home?

Do I need a water filter in Singapore?

For safety, no. Our explainer, is tap water safe to drink, covers why water from the kitchen tap can go straight into a glass. So if you are asking "do I need a water filter in Singapore", the honest answer is that it is a comfort choice.

PUB publishes the numbers. Its drinking water quality report lists calcium from 2.81 to 74.6 mg/L and total hardness (as CaCO3) from 7.24 to 191 mg/L. If you want to know what comes out of your tap, read that report rather than a filter brochure.

People who fit a unit usually have a specific reason. Some dislike the taste. Some live in an older resale HDB flat or a landed home where the pipes inside the house have been in place for decades. Others just want a separate drinking tap beside the sink. These are all fair reasons, but none of them is a health requirement.

Under sink water filter installation, step by step

A standard kit has three parts: a tee that splits the cold supply, a housing that holds the cartridge and a slim drinking tap.

1. Measure the cabinet. Clear it out and check the room beside the waste pipe and bottle trap, including hand space below the housing to unscrew the cartridge.
2. Shut the angle valve. Close the small valve feeding the kitchen tap, then open the tap to release pressure. Keep a towel and a basin underneath.
3. Fit the tee. Undo the flexible hose at the angle valve, fit the kit's tee adaptor and reconnect the hose so the kitchen tap still works.
4. Mount the housing. Screw the bracket to the cabinet side wall, clear of the base where water collects.
5. Connect the filter tap. Use a spare hole in the sink or a new hole in the counter, fit the tap and run tubing from tee to housing to tap.
6. Flush the cartridge. Open the valve slowly and run the filter tap for as long as the maker's sheet says before you drink from it.
7. Watch for drips. Lay dry tissue under each joint and check it over the next day.

Under-sink leaks are easy to miss in a dark, crowded cabinet. If water pools after the install, work through our checks for a kitchen sink leaking underneath before blaming the filter. The waste pipe and bottle trap can leak too.

Who should do the work

PUB says all regulated water service and sanitary plumbing works must be done by PUB Licensed Plumbers, except the simple plumbing works handymen may do. Installing or replacing a washbasin or sink and its bottle trap is one of those simple works. Since 2018 it has been an offence to engage a plumber not licensed by PUB for regulated works (PUB: Plumbing Works).

Most under-sink kits connect to the existing cold point with a tee and tubing and leave the pipes in the wall alone, which makes them a simple fitting. New piping is different. Running a fresh line to a condo island counter or moving the supply point is plumbing work for a licensed plumber. Our guide on what needs a licensed plumber explains where that line sits. If an installer cannot tell you which side of it your job falls on, find someone who can.

Water filter Singapore HDB: space and fittings

In most HDB kitchens the sink cabinet already holds the waste pipe, the bottle trap, the angle valve and years of cleaning supplies. Empty it and measure before you buy. A single housing needs less room than a multi-stage unit.

Next comes the tap hole. A stainless steel sink may already have a spare hole, but a solid counter needs one drilled. If you would rather not drill, some households fit a kitchen mixer with a separate filtered outlet instead, which turns the job into a tap replacement.

Then check the cabinet floor. Soft, bulging or stained board points to an old leak. Fix that first, using our notes on a swollen cabinet under the sink, because a new filter in a damp cabinet only hides the next drip.

Cartridge care

Treat the cartridge as a consumable. Follow the replacement interval the maker gives for your model, and write the fit date on the housing with a marker. If the maker states a volume as well as a time, go by whichever comes first.

PUB advises flushing service pipes or a water heater whose water has been stagnant for a long time before using the water, especially for drinking (PUB: Drinking water quality). The same habit helps with a filter: after a long holiday, run the filter tap for a while before you fill a glass.

Discoloured or smelly water

A brown glass is not a reason to buy a filter. PUB says drinking water is normally clear but very occasionally may appear discoloured or contain particles, from maintenance such as routine cleaning of water tanks, flushing of service pipes in buildings and testing of fire hydrants, or from internal fittings and installations in homes. Let the tap run until clear before drinking. If it is not clear after 5 to 10 minutes, call 1800-CALL-PUB (PUB FAQs).

Our guide to discoloured tap water covers what to check inside your home. If a smell comes only from the filter tap and not the kitchen tap, start with the cartridge.

Questions