Domakihub How to Fix a Running Toilet (Stop the Waste Fast)
Silence that endless trickle in minutes with a few simple tank checks.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 4 min read
A toilet that never stops running is more than an annoying hiss in the night; in Greece, where every home, apartment, holiday rental and hotel is metered, it can quietly waste hundreds of litres of water a day and inflate your bill. The HGTV video above shows the repair on real tank hardware, and this guide walks you through the same checks step by step so you can fix it yourself in most cases. If the parts are worn or the problem returns, a quick visit from a plumber settles it for good.
Why a toilet keeps running
Almost every running toilet comes down to one of two parts inside the tank. The flapper (or flush valve seal) is the rubber piece that lifts when you flush and drops back to seal the tank; when it hardens, warps or gets coated in mineral scale, water leaks past it into the bowl and the fill valve keeps topping the tank up forever. The other culprit is the fill valve and float: if the float sits too high, water rises above the overflow tube and drains away continuously.
In hard-water areas common across much of Greece, limescale build-up speeds up flapper wear and can stiffen the fill valve, so these issues tend to reappear every couple of years. The good news is that both parts are cheap, sold in any hardware or plumbing shop, and replaceable without special tools.
What it costs you to ignore it
A slow, silent leak past the flapper can waste anywhere from 70 to several hundred litres a day, while a tank overflowing into the tube wastes even more. Over a month that is a meaningful jump on the water bill, and for owners of multiple rental units or hotel rooms it multiplies fast. A guest is also far less likely to leave a good review if the bathroom hisses all night.
Fix it in five steps
- 1
Confirm the leak and shut off the water
Listen for a hiss or watch for water trickling into the bowl long after a flush. To be sure, add a few drops of food colouring to the tank and wait 15 minutes without flushing; if colour appears in the bowl, the flapper is leaking. Then turn off the supply at the small valve on the wall behind the toilet (turn clockwise) and flush to empty the tank.
- 2
Inspect the flapper
Lift the tank lid and look at the rubber flapper at the bottom. Press it down gently and feel for cracks, stiffness, warping or a slimy mineral coating. Check that the chain connecting it to the flush lever has a little slack; a chain that is too short or tangled holds the flapper open. Adjust the chain length first, as that alone fixes many running toilets.
- 3
Replace a worn flapper
If the flapper is hard, split or scaled, unhook it from the pegs on the overflow tube and unclip the chain. Take the old one to the shop to match the size and style, then snap the new flapper onto the pegs and reconnect the chain with slight slack. Universal flappers fit most modern tanks sold in Greece.
- 4
Check and adjust the fill valve and float
Turn the water back on and watch the tank refill. The water should stop about 2 to 3 cm below the top of the overflow tube. If it rises higher and spills into the tube, lower the float: turn the screw on top of the fill valve, or pinch the clip on the float arm and slide it down. Refill and confirm the level settles below the overflow.
- 5
Test, and replace the fill valve if needed
Flush a few times and watch the tank refill and shut off cleanly with no ongoing hiss. If the valve still runs, leaks at the top or never fully stops, replace the whole fill valve: shut off the water, disconnect the supply line, unscrew the locknut under the tank, fit the new valve, and reconnect. If anything leaks under the tank or you are unsure, call a plumber rather than risk water damage.
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FAQ
- How do I know if it's the flapper or the fill valve?
- Do the food-colouring test: add a few drops to the tank and wait 15 minutes without flushing. If colour seeps into the bowl, the flapper is leaking. If the tank water keeps rising and spilling into the central overflow tube instead, the fill valve or float is set too high or faulty.
- Is a running toilet really worth fixing right away?
- Yes. Even a silent leak can waste tens to hundreds of litres a day, which adds up quickly on a metered Greek water bill, and across several rental or hotel units it is significant. The parts cost only a few euros, so a same-day fix almost always pays for itself.
- When should I call a plumber instead of doing it myself?
- Call a professional if the leak is under the tank, the shut-off valve is seized or dripping, the problem returns soon after a repair, or you are not comfortable swapping the fill valve. For rentals and hotels, a plumber can also service several units at once and check for hidden limescale damage.