Plumbing issues in Singapore apartments tend to cluster around three problems: dripping taps, slow-draining sinks and running toilets. In older HDB estates — Toa Payoh, Queenstown, Ang Mo Kio — the galvanised steel pipes installed in the 1970s and 1980s have largely been replaced during PUB-mandated upgrading programmes, but internal fittings such as tap cartridges, trap seals and cistern valves still require periodic attention.
Fixing a Dripping Tap
A tap that drips once per second wastes roughly 10,000 litres of water per year. At PUB's current tariff of SGD 3.69 per cubic metre (including the water conservation tax and waterborne fee), that amounts to about SGD 37 annually for a single tap.
Ceramic Disc Taps (Most Common in Post-2000 Flats)
Modern mixer taps use a pair of ceramic discs that rotate against each other. When these discs wear or accumulate mineral deposits from Singapore's treated water, the seal becomes imperfect. To replace the cartridge:
- Turn off the water supply at the angle valve under the sink. In most HDB flats, each tap has its own isolation valve — a small chrome handle located where the flexible hose connects to the wall pipe.
- Open the tap to release residual pressure.
- Remove the decorative cap on the handle (usually a snap-fit plastic disc marked H or C). Use a flat screwdriver to pry it off gently.
- Unscrew the handle retaining screw (Phillips head or Allen key, depending on brand).
- Use an adjustable wrench to unscrew the cartridge from the tap body. Note the orientation — cartridges are keyed with flat edges or tabs that must align correctly on reassembly.
- Take the old cartridge to a plumbing supply shop. The row of shops at Block 462 Crawford Lane (near Lavender MRT) carries cartridges for most brands sold in Singapore, including unmarked OEM taps supplied by HDB-appointed contractors.
- Install the new cartridge, reassemble in reverse order, turn on the angle valve, and test.
Compression Taps (Older Flats)
These use a rubber washer that compresses against a brass seat. The washer is a consumable part and costs less than SGD 1. Remove the handle and bonnet nut, pull out the jumper valve, pry off the old washer, press on the new one, and reassemble. If the drip persists, the brass seat may be scored — a tap reseating tool (about SGD 15 at Selffix) grinds the seat flat.
Clearing a Slow Drain
Bathroom sinks and floor traps in Singapore apartments frequently slow down due to hair, soap residue and the mineral deposits that form more readily in warm water. Chemical drain cleaners such as Mr Muscle and Drano are widely sold, but they can corrode older brass trap assemblies. Mechanical methods are more reliable for recurring blockages.
Method 1: Baking Soda and Vinegar
Pour 100 g of baking soda into the drain opening, followed by 200 ml of white vinegar. Cover the opening with a wet cloth for 15 minutes, then flush with a full kettle of boiling water. This dissolves soap scum and light grease buildup without affecting pipe materials.
Method 2: Drain Snake
A 5-metre flexible drain snake (SGD 8 to SGD 12 at most hardware stores) reaches past the trap bend to dislodge hair clogs. Insert the snake into the drain, rotate the handle clockwise as you push forward, and retract slowly when resistance decreases. Clean the retrieved debris and flush with hot water.
Method 3: Removing and Cleaning the Trap
Under-sink P-traps unscrew by hand in most modern installations. Place a bucket underneath, unscrew the two slip nuts, remove the curved section, clean it thoroughly, and reinstall. Replace the rubber washers at the joints if they appear compressed or cracked — a set of three costs about SGD 2.
Stopping a Running Toilet
A running toilet can waste over 750 litres per day. The noise is also a nuisance, particularly in HDB flats where bathroom walls are thin and sound transmits to adjacent units.
Diagnosing the Cause
Lift the cistern lid and observe the water level. If water is flowing over the top of the overflow tube, the fill valve is not shutting off — the float may be set too high, or the valve diaphragm may be perished. If the water level is below the overflow tube but water still trickles into the bowl, the flush valve seal (flapper) is leaking.
Adjusting the Float Level
Most cisterns in Singapore use a side-entry fill valve with a plastic float arm. Bend the arm downward slightly (for brass arms) or turn the adjustment screw on the float (for plastic arms) until the water level sits about 25 mm below the overflow tube.
Replacing the Flush Valve Seal
Turn off the water supply, flush the toilet to empty the cistern, and disconnect the flush valve tower by twisting it counterclockwise (for dual-flush systems) or unclipping the chain (for single-flush). The rubber seal at the base lifts off. Take it to a hardware shop to match the diameter — 50 mm and 63 mm are the two standard sizes in Singapore. Install the new seal, reassemble, and turn the water back on.
When to Call a Licensed Plumber
PUB requires that any work on shared water supply pipes or sanitary stacks be performed by a licensed plumber registered with PUB. The following tasks fall outside the scope of DIY repair:
- Replacing angle valves or stop taps connected to the incoming water supply
- Any work on the vertical waste stack or shared drainage risers
- Installing new plumbing points (e.g., adding a bidet spray line)
- Water heater connections
The PUB Licensed Plumber Directory lists all registered professionals by area. Rates for common call-outs in 2026 range from SGD 60 to SGD 120 for the first hour, plus parts.
For general information about water supply and drainage responsibilities in HDB estates, refer to PUB's homeowner guidelines at pub.gov.sg.