Quick answer
A toilet keeps running after a flush when the inlet valve doesn't shut off, so water spills into the overflow pipe, or when the outlet-valve seal leaks into the bowl. In an HDB flat, lift the cistern lid and check the water level first. SG QuickFix fixes a running toilet from $70.
SG QuickFix pricesTap to WhatsApp
| Toilet keeps running repair | From $70 |
| Flush button repair | From $60 |
| Internal cistern repair | From $80 |
| Flush valve replacement+ part | From $90 |
Current SG QuickFix starting prices. Final price confirmed before work begins.
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Why does my toilet keep running after I flush?
A toilet keeps running after a flush when the inlet valve won't shut off or the outlet valve leaks into the bowl.
The inlet valve (fill valve) refills the cistern and should close as the ball float rises. If the float is set too high or the valve's washer is worn, water spills down the overflow pipe into the bowl.
The outlet valve (flush valve) drops back onto a rubber seal after each flush. If that seal is worn, warped or gritty, water trickles into the bowl and the inlet valve keeps topping up, so you hear it hiss on and off.
HDB's toilets care guide groups two symptoms, slow filling and water continuously flowing into the pan after flushing, with three possible causes: an angle valve (which HDB calls the ball valve) beside the cistern that isn't fully open, a ball float set too high or too low, and an outlet-valve rubber seal that is defective or stuck with fine particles. Of these parts, the rubber seal usually wears out first.
BTO flats come with dual-flush water closet suites. Most HDB flats have an exposed cistern with a push button on the lid; many renovated flats have a concealed cistern behind a wall flush plate.
To stop the water now, turn the angle valve beside the cistern clockwise to close it; if it's seized, close the stopcock at your flat's PUB water sub-meter, just outside your main door or in a service cupboard. For a repair, see the toilet repair service.
Is it the inlet valve or the outlet seal?
Lift the cistern lid: if water is spilling into the overflow pipe, it's the inlet valve; if not, a dye test checks the outlet seal.
- Unscrew the push-button knob anti-clockwise, lift the heavy ceramic lid off with both hands and lay it on a towel.
- Wait for the cistern to finish filling.
- If water is running into the top of the overflow pipe, the inlet valve is at fault.
- If the level sits below the overflow, add a few drops of food colouring or a PUB leak detection tablet.
- Don't flush. Wait 10 to 20 minutes.
- Coloured water in the bowl means the outlet-valve seal is leaking.
- Flush afterwards to clear the colour.
This is the food-colouring test in PUB's tips on finding leaks; PUB's water-saving items page offers the tablets.
How do I fix a running toilet myself?
Many running toilets are fixed by lowering the water level or cleaning the outlet seal; a worn seal, float or washer needs a new part.
If the cistern fills slowly and hisses for a long time, first check that the angle valve beside it is fully open, as HDB advises.
Water spilling into the overflow: lower the water level
- Find the adjusting screw on the inlet valve, where the float arm or float cup meets it.
- Turn the screw a little to lower the float.
- Flush and let the cistern refill.
- Check the water stops at the WL mark, or about 20 to 25 mm below the top of the overflow pipe.
- Repeat until the hissing stops once the cistern is full.
If the float is cracked or full of water, replace the float. If the valve still won't shut, its washer or the whole inlet valve needs replacing; see the licensing note below.
Colour in the bowl: clean or replace the outlet seal
HDB's tip: press and hold the flush button for a few seconds to wash fine particles off the seal. If dye still reaches the bowl, close the angle valve, flush to empty the cistern, and lift or unclip the outlet valve. Wipe the rubber seal and its seat with a damp cloth, not an abrasive pad.
HDB says to replace the rubber seal if it's defective: one that is hard, cracked or out of shape won't seal again. Seals are brand-specific, so take the old one, or a photo of the brand name, to the shop.
What if it's the flush button or a concealed cistern?
A sticking button or over-long rod holds the outlet valve open, and you can adjust the rod; a concealed cistern is usually a plumber job.
The button presses a rod or pulls a cable that lifts the outlet valve. Too long, and the valve never fully drops onto its seal; too short, and the flush is weak. Leave a gap of a few millimetres when the button is at rest, then repeat the dye test.
A button that stays down usually has a broken spring or cracked housing.
Concealed cisterns are reached through the flush-plate opening, the space is tight and the parts are brand-specific. HDB also advises engaging a plumber if your flushing system is an "exclusive" type that doesn't match the illustrations in its guide.
How much does it cost to fix a running toilet in Singapore?
SG QuickFix fixes a running toilet from $70; replacing a valve is a separate job, plus the part.
| Job | When you need it | SG QuickFix price |
|---|---|---|
| Toilet keeps running repair | Set the water level, clean or reseat the outlet seal | From $70 |
| Flush button repair | Button sticks, or the rod holds the valve open | From $60 |
| Internal cistern repair | Concealed cistern, or several parts at once | From $80 |
| Flush valve replacement | Dye still reaches the bowl after cleaning the seal | From $90 plus the part |
The price rises when a valve or seal must be replaced, the cistern is concealed, or brand-specific parts must be ordered. Each job is priced separately. Adjusting or cleaning usually takes 15 to 30 minutes; a concealed cistern can take up to about 2 hours.
For an accurate price, send a 10-second video of the cistern with the lid off just after a flush, plus a photo of the brand name or flush plate. See all toilet repair prices and the full plumber price list for Singapore.
Water on the floor is a different fault: see the guide to a toilet bowl leaking at the base. If your water meter still moves with every tap off after the toilet is fixed, a hidden pipe may be leaking: that's a leak repair job.
Do I need a licensed plumber to fix a running toilet?
Not by law: PUB lists replacing a cistern's flushing mechanism as simple plumbing work that an unlicensed handyman may do.
PUB's list doesn't name the inlet (fill) valve or the angle valve, so have a PUB Licensed Plumber replace either. Changing the toilet bowl itself always needs one. In an HDB flat, the owner pays for cistern repairs once the 1-year Defects Liability Period (DLP) from key collection has ended. For the wider rules, see which plumbing jobs need a PUB-licensed plumber.
| Safe to DIY if… | Call a professional if… |
|---|---|
| Water spills into the overflow and the float screw lowers it | The inlet valve won't shut after adjusting |
| Pressing and holding the button stops the trickle | Dye still reaches the bowl and you can't get the right seal |
| The cistern is exposed, with a push-button knob that unscrews | The cistern is concealed behind a wall flush plate |
| You can find a seal made for your cistern's brand | The mechanism is an "exclusive" type HDB says needs a plumber |
| The water meter stops once the toilet is fixed | The meter still moves with every tap off: suspect a hidden pipe leak |
| Not a DIY job | The toilet bowl itself must be removed or replaced: PUB Licensed Plumber work |
What happens when you WhatsApp us?
- 1WhatsApp us a photo or short video of the problem.
- 2We confirm the price before we come.
- 3A technician arrives at the agreed time.
- 4The job is done and you pay only the confirmed price.
Toilet Repair
From $70
- Cistern & flush repair
- Seal & gasket replacement
Toilet Repair FAQs
PUB says a silent cistern leak can waste more than 10 litres an hour. A slow leak into the bowl is often silent, so it can run for weeks before anyone notices. If your water bill jumps with no change in use, do the dye test on every toilet in the flat.
A running toilet rarely stops on its own: a worn seal or mis-set float stays that way. It normally won't flood the bathroom, because the overflow pipe drains into the bowl. A choked bowl is the exception: it can fill and spill over, so close the angle valve (which HDB calls the ball valve) beside the cistern at once.
A toilet that refills by itself, with a short hiss every few minutes or hours, usually has a slow leak at the outlet-valve seal. Water seeps into the bowl until the level drops enough to open the inlet valve. A dye test confirms it; cleaning or replacing the seal stops it.
In-cistern cleaners containing bleach or chlorine can harden and warp rubber seals and plastic parts over time, and Fluidmaster, a cistern-valve maker, warns against them. Clip-on rim cleaners that hang in the bowl keep chemicals away from the cistern parts, so they are a safer choice for a dual-flush cistern in an HDB flat.
HDB rectifies maintenance issues in a new flat within the 1-year Defects Liability Period (DLP) from key collection, so report a running toilet to HDB within that year. After it ends, the flat owner pays for repairs to sanitary fittings inside the flat, including the cistern. In a rented flat, check the tenancy agreement for who handles minor repairs.
Yes. PUB offers leak detection tablets that you drop into the toilet cistern to show silent leaks into the bowl. Request them through the form on PUB's water-saving items page. Food colouring from the supermarket works the same way if you want to test your toilet today.
Related services
Serving Bedok, Pasir Ris, Punggol, Sengkang and Tampines and island-wide.
Sources & updates
- HDB: Home care guide, toilets, checked 1 Oct 2026
- PUB: Tips on finding leaks (PDF), checked 1 Oct 2026
- PUB: Water-saving items, checked 1 Oct 2026
- PUB: Plumbing works (licensed plumbers and simple works), checked 1 Oct 2026
- MyNiceHome (HDB): HDB maintenance guide, checked 1 Oct 2026
- MyNiceHome (HDB): HDB move-in guide, checked 1 Oct 2026
- Updated 1 Oct 2026: First published
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This guide is general information for homes in Singapore. It is not professional, legal or safety advice for your specific situation. Electrical, gas and some plumbing work can be dangerous, and Singapore law requires certain jobs to be done by licensed workers. Any work you carry out yourself is at your own risk, and SG QuickFix accepts no responsibility for any loss, damage or injury arising from the use of this information. Prices shown are current starting prices, may change, and the final price is confirmed before any work begins. Rules and figures from HDB, PUB, EMA, SP Group and town councils were correct when last checked; please confirm with the relevant authority before acting.