Why a toilet keeps running
Most running cisterns fall into one of two situations. Either the water level is set too high, so water keeps overflowing into the bowl, or the flush seal leaks, so water slips into the bowl and the cistern keeps refilling. If your toilet cistern keeps filling between uses, start with these two.
HDB's home care guide for toilets lists cistern overflow and slow fill alongside fixes. It treats a bowl that drains slowly as a different problem, a choke from a partial blockage in the sanitary pipe: see how to unclog a toilet.
Other signs of a leak listed on PUB's water saving items page include unusually high water bills, the sound of running water or dripping at night when nothing is in use, mould or peeling paint on walls, floors or ceilings, and foul odours with no other source.
Test for a silent leak
PUB offers households leak detection tablets that find silent leaks in flushing cisterns, as its water saving items page explains. Its tips on finding leaks give food colouring as another option.
- Lift the cistern lid. Take the lid off the tank and set it down safely.
- Add the tablet or colouring. Drop one leak detection tablet, or some food colouring, into the cistern tank.
- Put the lid back. Close the tank so the test runs undisturbed.
- Wait without flushing. Leave the toilet for 10 to 20 minutes and make sure nobody flushes it.
- Check the bowl. Coloured water in the bowl means the cistern is leaking. With a tablet, look for blue water.
You can also check by eye. PUB's water saving items page suggests looking for water streaks entering the toilet bowl, or a ripple in the bowl water.
Adjust the water level and float
HDB's toilets guide gives three fixes for cistern overflow and slow fill: adjust the water level screw, replace a damaged ball float, or replace a worn washer. Compare your cistern with HDB's illustrations before you change anything.
| Part | What to look for | Fix |
|---|---|---|
| Water level screw | Water overflowing into the bowl | Adjust the screw |
| Ball float | Damage to the float | Replace the float |
| Washer | Signs of wear | Replace the washer |
The same HDB guide says to engage a plumber if your flushing system is different from the one in its illustrations.
What it does to your water bill
A leaking toilet can waste water quietly. PUB's tips on finding leaks say a leaking cistern can lose more than 10 litres of water an hour, and that prolonged leaks lead to high water bills, water wastage and possible damage to your property.
The same PUB guide suggests a meter test. Turn off all taps and water-using appliances, then watch your water meter for at least 10 minutes. If the dial moves, there is a leak.
PUB's meter reading guide says unusual spikes in usage, or the dial moving when no water is in use, may suggest a leak. In an HDB flat, the meter is along the common corridor near your unit entrance, exposed or in a utility duct, or at the staircase landing below your unit.
A moving dial shows a leak but not where, so follow it with the dye test. For routine checks, see the guide to bathroom maintenance.
Published toilet repair rates
11 companies in the directory publish a toilet repair line, all per job. Their published rates run from S$80 to S$150 per job, as printed, for one toilet part such as the siphon, valve or flush system. S$90 per job sits in the middle, and it is one company's own published rate.
FROM THE HOMEZYPRO DIRECTORY
Published toilet repair rates
For the most common unit (per job), the lowest published toilet repair rates from 11 companies run from S$80 to S$150 per job (middle rate S$90), for one toilet part such as the siphon, valve or flush system. The middle figure is a real published rate, not an average. Each figure is one company's own advertised rate with its conditions, not a quote.
See 11 published toilet repair rates and sources
| Company | Service as listed | Rate | Source |
|---|---|---|---|
| Anytime Plumber.sg | Rectify water discharge into toilet bowl by replacing new siphon | From S$80 per job | anytimeplumber.sg |
| EZ Plumber SG | To rectify water discharge into toilet bowl | S$80 per job | ezplumber.sg |
| SG1 Plumber Singapore | WC Flush Cistern Replacement | S$80 per job | sg1plumber.com |
| Sin Plumbing Singapore | Rectify water discharge into toilet bowl by replacing new siphon | From S$80 per job | sinplumbing.com |
| Uncle Plumber | Rectify water discharge into the toilet bowl by replacing new siphon | From S$80 per job | uncleplumber.sg |
| Home Plumbers Singapore | Replace a toilet bowl valve | From S$90 per job | homeplumbers.com.sg |
| Active Plumbing Singapore | Rectify water discharge into toilet bowl by replacing new siphon | From S$100 per job | activeplumbing.sg |
| Ace Plumbing Specialist | Rectify water discharge into toilet bowl by replacing siphon | From S$130 per job | aceplumbing.sg |
| Sk Plumber | Replace shower set / WC flush system | S$135 per job | sksplumber.com |
| Best Plumbing | Rectify water discharge into toilet bowl by replacing new siphon | From S$150 per job | bestplumbing.com.sg |
| Summer Plumbing Service | Rectify water discharge into toilet bowl by replacing new siphon | From S$150 per job | sgplumbing.com.sg |
Lines as printed include several siphon replacement lines from S$80, a WC flush cistern replacement at S$80, a valve line from S$90, lines from S$100 and from S$130, a shower set or WC flush system at S$135, and two lines from S$150.
No line prices a concealed cistern or work behind an access panel, so ask for a separate quote for those, and ask whether the rate includes the replacement part. See the companies listing toilet repair, and other jobs under plumbing costs.
PUB's Plumbing Works page advises discussing scope and cost first, asking for itemised quotes and getting at least three quotes.
NEXT STEP
See plumbing companies in the directory with their published prices, the areas they say they cover and their sources.
Compare plumbersWhen to stop and call a professional
Stop and call a professional if:
- your cistern is concealed and you cannot reach the parts
- the cistern itself is cracked
- water leaks onto the floor rather than into the bowl
- the fix does not hold and the cistern starts running again
PUB's Plumbing Works page lists replacing a cistern flushing mechanism among the simple plumbing works a handyman may do. Other regulated water service and sanitary plumbing works must be done by a PUB Licensed Plumber, including installing, changing or relocating toilet bowls and the sanitary piping system. Engaging a plumber who is not licensed for regulated works has been an offence since 2018.
For a leaking cistern, PUB's water saving items page says to call a licensed plumber to fix or replace it. You can find licensed plumbers in the directory.
If the bowl itself needs replacing, see toilet bowl replacement cost. For other warning signs, see signs you need a plumber.
Questions
Why does my toilet refill by itself every few minutes?
A leaking flush seal is a likely cause: water slips into the bowl and the cistern refills to replace it. It is not the only cause, so check with a dye test. Add a leak detection tablet or food colouring to the tank, wait 10 to 20 minutes without flushing and look for colour in the bowl.
How do I test my toilet for a leak?
Drop a leak detection tablet or food colouring into the cistern tank, put the lid back and wait 10 to 20 minutes without flushing. Coloured water in the bowl means a leak. PUB's water saving items page also suggests looking for water streaks entering the bowl or a ripple in the bowl water.
How much water does a running toilet waste?
PUB's tips on finding leaks say a leaking cistern can lose more than 10 litres of water an hour. The guide also warns that prolonged leaks lead to high water bills, water wastage and possible damage to your property, so test as soon as you suspect one.
Can I fix a running toilet myself?
You can try the fixes in HDB's toilets guide: adjust the water level screw, or replace a damaged ball float or a worn washer. If your flushing system differs from HDB's illustrations, the cistern is concealed or cracked, or water leaks onto the floor, call a plumber.
Where can I get PUB leak detection tablets?
PUB offers leak detection tablets for flushing cisterns to households through its water saving items page. Check PUB's page for how to get them. If you do not have a tablet, PUB's tips on finding leaks suggest putting food colouring into the cistern tank instead.
How much does it cost to fix a running toilet?
11 companies in the directory publish a toilet repair rate for one part, such as the siphon, valve or flush system. Their published rates run from S$80 to S$150 per job, as printed, with S$90 in the middle. No line prices a concealed cistern, so ask for an itemised quote for that.
Prices come only from the sourced company rates in the HomezyPro directory, shown with each company and its source.
Practical guidance for planning a home job in Singapore. Company prices come from the HomezyPro directory, each linked to its source; rules and safety points link to the agency or manufacturer that sets them. This is not a site inspection, a quote or professional advice for your home.
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