Toilet keeps running: causes and the fix
A toilet that keeps running almost always has one of two faulty parts: the float valve, which fails to shut off the incoming water, or the flush valve, which lets water leak into the pan. Close the small isolating valve on the toilet supply to stop the waste, then call someone to replace the part.
Why the toilet keeps running
The cistern, the tank behind or above the toilet, has two parts that work together. The float valve lets water in and shuts off when the cistern is full. The flush valve, at the bottom, opens when you press the button and closes again. When either one stops sealing, water runs non stop, sometimes noisily, sometimes in silence.
The float valve will not shut off
The cistern fills, but water keeps coming in and escapes down the overflow pipe into the pan. Usually the float is stuck, there is limescale in the valve or a washer is worn.
The flush valve is not sealing
A thin trickle runs down the back of the pan and the cistern refills every so often to make up the loss, sometimes in the middle of the night with nobody touching it. It is the sneakiest case, because you barely hear it, and it is the most common cause of an unexplained high water bill.
What you can check yourself
None of these checks needs tools or taking anything apart.
- Wipe the back of the pan, inside, with dry toilet paper and wait a few minutes. If it gets wet again, water is leaking from the cistern.
- If the cistern is exposed, lift the lid and see whether water is spilling into the overflow pipe, the upright tube open at the top. If it is, the float valve is not shutting off.
- Check whether the float is caught against the side of the cistern or on the flush chain. Freeing it by hand sometimes solves it.
- Press the button and let go. Some buttons stick halfway and hold the valve open.
What to avoid
Do not force old plastic parts, which snap easily, and do not leave tablets or harsh products in the cistern, because they damage the seals. With a concealed cistern, the access is through the flush plate on the wall: if you do not know how it comes off, leave it.
How to stop the water while you wait
A running toilet will not flood your home, because the water goes down the drain. But it wastes water around the clock and shows up on the bill. To stop it, close the isolating valve, the small tap on the pipe that feeds the cistern, usually on the wall beside or below it.
You can still use the toilet: after flushing, open the valve until the cistern refills and close it again, or pour a bucket of water straight into the pan. If the valve is stiff, do not force it, because an old valve can start to drip.
If there is water on the floor
That is a different problem: it may be a leak at the water connection or at the seal under the pan. Close the valve, dry the floor and call without leaving it for later, because standing water ruins floors.
When to call a plumber and how the repair goes
Call when the checks do not fix it, when there is water on the floor, when the cistern is concealed in the wall or when a part is broken. For a plumber, toilet repair means replacing the part that has failed, not the toilet: in toilet repair in Porto we change the float valve, the flush valve or the whole mechanism. Concealed cisterns are opened through the flush plate, the intended access point, without touching the tiles.
You call or send a message
A person answers. We ask for your address, whether the water runs all the time or now and then, and whether the cistern is exposed or in the wall. A photo on WhatsApp helps us bring the right part. If you need a fast response, call rather than message, and we give you a real arrival time and agree payment on the phone.
Diagnosis and quote
The technician opens the cistern, finds which part is failing and shows it to you. The quote is free, given before any work, and nothing goes ahead without your approval. If the mechanism is not worth repairing, we say so.
We repair and test in front of you
We replace the part and flush several times to confirm the cistern fills, shuts off and stays quiet. If the part for that model has to be ordered, we tell you how long it will take rather than inventing a date.
You keep the invoice
The invoice lists the work and the materials separately. That document is your guarantee and what entitles you to complain if the toilet starts running again.
Running toilet or blocked toilet?
Sometimes the complaint is a toilet that fills up and empties slowly. That is not the cistern. If the water rises in the pan and drains slowly, or the drains gurgle when you flush, it is a blockage and the right service is drain unblocking in Porto. The warning signs are in our guide to a blocked drain.
Running toilet questions
The cistern only runs sometimes. Is it worth a call out?
It is. A valve that seals poorly passes water silently and is the most common cause of an unexplained high bill.
Does the toilet need replacing?
Almost never. What fails are the parts inside the cistern, and they are replaced without touching the toilet.
Do you come out at night or at weekends?
Yes, we answer 24 hours a day, every day of the year. But with the isolating valve closed, this is a job that can wait for a time that suits you.