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Is your toilet cistern still running after flushing? As annoying as this often is, it doesn’t have to be a sign that something truly terrible is going on. Often the cause is something quite common and can often be fixed by you in the comfort of your own home. Throughout this post we’ll take you through the most likely causes and their fixes, and if that doesn’t help, it’s probably time to call a plumber… But we’re getting ahead of ourselves, for now, here’s everything you need to know about your toilet cistern still running after flushing!

Float Valve VS Flush Valve

If your toilet cistern is running after flushing continuously, then it’s likely that either your float valve or flush valve is having problems. Your float valve controls the flow of water into the cistern, so if there is a problem there, it could just keep the water flowing constantly, even though you aren’t still flushing.

The second one isn’t to do with the cistern itself, but it’s often banded together in the same category because the ‘symptoms’ of your flushing toilet are often the same. Your flush valve controls the flow of water into the pan or toilet bowl. If this is broken, then it can sound as if it is still flushing even though you aren’t doing anything to it because water is constantly leaking from the cistern.

Lever Flush VS Button Flush

We thought it would be helpful as you try to diagnose this problem to keep something in mind. A toilet that flushes via a siphon (you’ll notice this by the lever that raises water above the spillover point to release water into the pan) doesn’t have a flush valve. That’s because a flush valve allows water to enter the pan through gravity alone, by simply opening and then closing again once it has released the water, there is no siphoning.

Why are we telling you this? Because a toilet with a siphon doesn’t have a flush valve, so if you are having an issue with your cistern still running after flushing, then it’s almost certainly the float valve at this point.

But don’t worry, you don’t need to know whether you have a siphon or a flush valve based on how it looks. That’s because:

– Toilets with a siphon usually operate via a lever flush

– Toilets with a flush valve usually operate via a button flush

So, if you have a lever flush, it’s most likely a float valve issue, not a flush valve. And if you have a button flush, then it can be either a flush valve issue or a float valve issue. But don’t worry, we’ll tell you how to identify and then fix both below!

Identifying The Specific Problem

First, shut off the water supply to the cistern. There’s an isolation valve on the supply pipe, but if you can’t find this, then simply turn off the water at the mains. Now all you need to do is wait.

Wait for an hour. If the leak stops and the cistern is no longer running, then the float valve is the problem.

If, after an hour, the water is still running, then the problem is the flush valve.

Now you know the issue, let’s look at what the potential problems are, and tell you how to fix them! We’ll start with the float valve, since this is a problem that can effect any toilet.

Float Valve Fixes

There are three common problems with a float valve, and we can fix all of them quickly in the same way. The first issue is that the washers and valve seatings can become worn after so many uses. When this happens, the seal is no longer watertight, so water constantly flows into the cistern.

The second issue is that a float valve can simply break or become jammed in the open position. Again, this signals that water needs to flow into the cistern constantly, which is why your cistern is still running long after you’ve flushed.

And finally, floats can become waterlogged, detached from the float arm, or have a build up of dirt inside them. There are cleaning products available that may fix the issue if it’s the latter. However, if this doesn’t work, then you will need to do the next step anyway, so to avoid extra expense, it may be worth skipping the cleaning part.

The quick, easy, and affordable fix for all of these issues? Replace the float valve. It’s that simple, because by the time you’ve paid for new washers and valve seatings, or float valve cleaning products, you might as well just have picked up a whole new float valve considering how inexpensive they are.

Replacing The Float Valve

There are plenty of YouTube videos detailing how to do this if you’re more of a visual learner, but if you prefer a quick general guide, then here it is:

– Turn off the water supply by turning the water shut-off valve clockwise until it stops moving

– Drain the tank by flushing

– Detach the toilet fill valve with pliers or a wrench – this valve is located off to one side – and pull it out gently

– Get your new float valve and put it into place

– Look at package instructions to make sure all washers and valve seatings are in place and watertight

– Tighten the fill valve nut again to keep it in place

– Turn on the water and test the flush – it should now be fixed

Flush Valve Fixes

The flush valve only really has one major issue associated with it, so it’s a much easier fix. It’s usually the case that the flush valve doesn’t have a watertight seal because of the main washer. When this is the issue, water will flow constantly from your cistern into the toilet pan or bowl because nothing is stopping gravity from taking the water down into the pan to flush.

The fix? This time you won’t need to replace the whole flush valve, but you will need to replace the main washer, or flush valve seal – they’re the same thing.

Replacing The Flush Valve Washer

Again, you can watch a video to guide you, but this general guide might help you too:

– Turn off the water supply by turning the water shut-off valve clockwise

– Drain the tank by flushing

– Identify the old valve seal at the bottom of the overflow tube and float

– Pull the seal until it breaks

– Gently stretch and pull the new valve over the overflow tube and float and navigate it towards the bottom of the cistern

– You should be able to get it into place and twist the seal into the groove until watertight – Turn water on and test the flush – it should now be fixed

Take-Home Message

If the following causes and fixes don’t help you, or you feel more confident having somebody do it for you, then contact a plumber. It’s usually a simple fix that can be done in 10 minutes or so once they’ve identified the problem. If you feel comfortable fixing the issue yourself, then the above guide ought to help you solve the issue in no time at all!

Looking for some tips that aren’t about your toilet? We have some great guides on Bedroom Decor Ideas and ways to furnish your flat or apartment on a budget.