Plumbers Assemble – toilet won’t stop flushing

Came home today to a rather annoying situation – my toilet won’t stop filling up. The float is raising to ‘close’ the valve but the valve does not close and water continues to pour into the cistern and then drain away into the pan. Aside from wasting water and costing money, the noise is bloody annoying and makes me want to go for a wee!!

We’ve turned the water off to shut it up and just turn it on when we need to use water but clearly this isn’t an ideal opportunity. Is this fix a call a plumber job or one that I could attempt myself with not a high level of DIY skill (ie I can plumb in a dishwasher but that is about it for plumbing)?

Cheers

fix it yourself .

Without pics I can only be vague .

What you have is an automatic fill valve that replens the amount of water in the cistern after each flush .

The fill level is controlled by a float and valve method.

Your valve diaphram has probably failed . Side entry or bottom entry ?

Either way , its water off , flush bog  a few times, sponge out cistern . Remove  metal flexy pipe , fit new valve  ( always buy Brass tails )  tighten into cistern , connect flexy , et voila

Assuming it’s the valve (massively likely), they’re easy to change in all (Both) the bogs I’ve done.

You may find that fine-tuning the ball “pressure” on the valve will do it, or also cleaning out any grit from the valve but a replacement is pretty cheap and likely very easy

Can you use a brick or something in the water tank to prevent the float from moving and thereby prevent the incoming water? If it’s a button flush there might be a jam in the button mech or twisted wires.

its not yhe flush valve though. the water fills the cistern and raises the float .

The overflow takes the still incoming water into the bowl = busted fill valve

Check the float thing can ‘float freely’ first.. Might just be gunked up if the float doesn’t float high enough to cut off the refill, it will keep drawing water.

Edited now, as it appears the fill valve doesnt shut off, so the internal overflow is running. New fill valve. The old one can be adjusted slightly, but IME, if they have staretd leaking, they need changing. Certainly easier than changing the flush valve, below.

Your flush valve is either damaged, or has dirt on its seal.
There are a number of different types, and, at least two sizes of outlet available, as well as different volumes in the older ones.
Changing it can be anything from 2 mintues to several hours.
Some just unclip, then you clip in the new section, leaving the bit that is in the bottom of the cistern in place. 2 minutes,and you dont even have to turn off the water.
Others will need the cistern removing. Firstly the bolts can seize and rust.Once they are off, and youve got the cistern off, it can be a right pain to get everything water tight. Scrupulous cleanliness and sealant paste work here, as well as tightening the correct amount. Then the rubber ring that seals between the cistern and pan can degrade over time, so may need replacing. Again, they can be a right pain to seal properly, but experience helps there.

My old toilet did that.

Bybtying a bit of string round the whole float arrangemenet and the tying it off to a convenient pipe running up the wall you could prevent the float from rubbing the side of the cistern and failing to float all the way to the top you could fix it.

By tightening the string occasionally you could get about 5 years out of it…

Push button flush? Could easily be the wee cable that runs down from the button to the syphon.  The can get corroded & leave the cistern permanently filling up.

Thanks for the replies – its a push button flush and the flush works fine when we press it, it is the fill valve that appears to be broken.
Sounds like I can have a bash myself tomorrow and the replacement unit is only a tenner or so from Screwfix. Plus an opportunity to buy some new tools for the job!

You’ll know if it goes wrong as I’ll come back here asking the best ways to limit damage from water leaking through a kitchen ceiling!!

Just to add, make sure the box for the new one is sealed. People tend to nick the rubber seal and return them!

happened to mine recently, just changing the diaphragm washer fixed it, no tools needed and took longer to turn the water off than change the washer.

Almost certainly the diaphragm has perished which will be sat under the float assembly. An adjustable (spring loaded) basin wrench is the correct tool (and a joy to use) to remove the float assembly as it’s a plastic part and can be stiff to turn.

The diaphragms are a couple of quid on eBay. It’s 100% DIY and you’ll feel like a plumbing god when you’ve fixed it.

On my push button one the flush assembly simply unclips at bottom and comes out. On the bottom is a large round washer which seals the hole which lets water from cistern into pan.

Eventually this blister’s letting water through. Often just need to replace that and problem sorted.