Blog>Expert Advice>Fixing a toilet that fills up with water when it's flushed
Last updated: 7 March 2024
Fixing a toilet that fills up with water when it's flushed
If you're dealing with a toilet that fills up with water when you flush it, then you're probably panicking every time you flush it and just hoping the water doesn't overflow! In this guide we'll cover everything from why your toilet fills up then slowly drains and home remedies to try and sort the problem.
Facing a toilet filled up with water in the middle of the night is never good. Imagine the impending doom as the toilet won't stop filling up. Panic will inevitably occur!
But when your toilet fills up when flushed, it isn't always a major cause for concern. There's a workaround for your U-bend.
To learn how to get to the root of your toilet flushing issues and how to fix them, keep scrolling.
Why is my toilet filling up when I flush?
If it fills up with water instead of flushing as usual, there could be several culprits.
Once you know the why, you can deal with the how.
Let's explore the causes of a toilet filling up with water once you flush it.
1. Clogged drains
A clogged drain is one of the most common causes of a toilet filling up with water.
Anything big enough to obstruct your drain can prevent water from flowing freely. This causes the water to come back up the toilet bowl when flushed.
Think about it: the water has to go somewhere.
Need more help? Dive into our guide 'how to unblock a toilet'.
2. Water supply issues
Any problems with your water supply valve or a malfunctioning fill valve can lead to inadequate water levels.
Insufficient water levels don't just interrupt flushing. They often lead to a toilet filled up with water.
Some of the common causes of water supply issues include leaks, overuse, a broken flush tube, and evaporation.
3. Faulty flapper
Yes, it might sound funny. But when your flapper becomes faulty, it doesn't feel funny.
The rubber seal that controls the water flow from your tank into the bowl is the flapper.
When your flapper is old, worn or damaged, it makes your toilet constantly run. Of course, this results in excess water, which is why your toilet fills up when flushed.
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Why won't the water go down when I flush?
When your toilet keeps filling up when flushed, other common causes to look out for include:
Blocked rim jets
A faulty float
Broken handle and chain
How do I stop my toilet from filling after flushing?
If your toilet keeps filling up when flushed, we have some helpful solutions you'll want to try.
1. Check for obstructions
Inspect the toilet bowl and drain hole for any visible blockages. Toilet paper, flushable wipes and foreign objects can cause obstructions.
Malfunctioning plumbing, like broken valves, can also create blockages.
Get to work with a plunger to dislodge any clogs in the toilet drain. You can try a toilet auger (a plumber's snake) for deeper blockages.
You might find our article 'who to call for a blocked drain' useful.
2. Test the flush
Try to observe the water flow while you flush the toilet.
If the toilet doesn't drain and fill as usual, there could be a deeper problem.
Or, if the flapper is working correctly, it shouldn't let more water through than usual. Flappers are fairly cheap and easy to install, so they're not too difficult to repair.
Call a trusted plumber if you have flush issues you can't get to the root of.
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3. Clear the drain line
If you've checked and plunged for apparent blockages with no luck, try snaking the drain line.
It might help to clear any stubborn clogs.
Or, if you'd prefer a less hands-on approach, try a drain-cleaning product specifically designed for toilets.
4. Look at the fill valve
You can also try adjusting the fill valve. Turn the adjustment screw of the fill valve to change the water level.
You can check your toilet's instruction manual for help if you need it.
If you don't have your toilet instructions (who does?!), it might be easier to call a local plumber.
5. Search for sediment buildup
If your toilet fills up with water and then slowly drains, the problem is probably with the rim.
When the rim jets get clogged with sediment, the water pressure drops. Then, there isn't enough force to push the bathroom's contents down the drain.
Use a small mirror to find these mineral deposits - they look like light or colour across the holes.
You can apply a mineral remover and wait a few minutes before. Chip away at the deposits with a screwdriver or strong wire.
6. Check your water levels
Low water levels in your tank are common causes of toilets filling up with water when flushed. They can also cause slow-draining toilets.
You can manually top up your tank with water to help the flush.
Then, check the flush tube for cracks and bends that lead to leaks. If you notice damage, install a new one for an easy fix.
If you've exhausted all possible avenues and your toilet still won't flush, it's time to call a plumber to take a look.
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Tips for unclogging a toilet with a plunger
Knowing how to use a plunger effectively can mean the difference between a clogged and unclogged toilet.
If you don't have time to wait for a plumber, work on your technique to unclog your toilet.
Act quickly. Remove the tank lid, find the flapper and push it down quickly to stop the water. Then turn off the water valve.
Choose the right plunger. Pick a funnel-style cup or any cup that gets you a good seal between the plunger and bowl.
Warm up your plunger. Mould your plunger to the bowl's shape. Pop it in hot water for a few minutes before using it (if time allows) to seal better over the drain.
Get the technique down. Seal your plunger over the drain properly, then plunge firmly up and down. Make sure your pullback motion is as firm as your downward motion.
If you unclog the toilet, water will rush from the toilet bowl. Then, turn the water back on and try to flush normally.
You might have a bigger problem farther down the drain if these tricks don't work.
We have a handy cost of unblocking a toilet guide, should you need it.
Finding plumbers to deal with your broken toilet
Hopefully, these home solutions for toilets filling up with water will get your toilet flushing normally.
But it's important to know when to call in for professional help. When none of these DIY solutions works, a plumber can get your flush like new.
Pop your postcode in the box below for a list of top-rated plumbers in your area.
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