5 reasons why your toilet won't flush – and how to fix it

Most of us have had that feeling of panic when the toilet won’t flush but don’t worry, there are a few simple steps you can take to sort it out quickly

Toilet flush
(Image credit: Getty Images)

How often have you gone to flush the toilet only for it to fill up with water? That feeling of panic when a toilet won't flush and you imagine it overflowing is not something you want to repeat, so by learning a few simple tricks, you can handle the worst if it happens again. 

Usually, these tricks will involve learning how to unclog a toilet

‘A toilet that won’t flush is actually a really common issue that’s usually easy to repair,’ according to the experts at Homeserve (opens in new tab). ‘Remember that with all home DIY projects, safety is important. If you don’t feel comfortable doing a task, it’s best to leave it to a professional plumber.’

Here are five of the most common reasons why your toilet won’t flush – and how to fix them.

Why your toilet won't flush, and what to do

It's not a job any of us look forward to, but it is one that can often be done without the bother and expense of calling in a professional. Here is what to check first.

1. Low water level

If there isn’t sufficient water in the toilet tank, it can’t flush as there isn’t enough water to refill the bowl. Look in the back of the tank and check if the water level is about an inch from the top of the overflow tube. 

If it isn’t, look for the float shaped like a round ball connected to the fill valve. Lift or bend the float arm up and the water level should start to fill. In toilets with an intake assembly, simply move the metal clip upwards to adjust the water level.

2. Flapper or lift chain issues

Another common cause of toilets that won’t flush is a problem with the flapper or lift chain. The flapper is the rubber cup shape at the bottom of the tank. The lift chain is attached to the top of this flapper and a long metal arm, which is the handle. 

When you flush, the metal arm usually rises, bringing the chain and flapper with it. If the chain is broken, it stops the flapper rising and letting water enter the bowl. If the flapper is damaged, this can cause water to constantly fill the bowl. In both cases, the toilet won’t flush and you need to replace the chain and flapper. 

To do this, turn the water off and flush. This empties the tank of water so you can easily access the flapper and chain. Remove and replace with new ones before testing a few times then turning the water back on.

3. Clogged toilet

It may be the case that your toilet is clogged up. Things like too much toilet paper, sanitary products, face wipes and other items can all cause the toilet to clog. 

An easy fix is to take a plunger or poke it with a loo brush to dislodge the clog. Try plunging three or four times and it should do the trick. If not, turn the water off, flush then add warm water to the bowl. Let it sit for a while and flush again. 

If this still doesn’t work, you may need to call a plumber in, who can use a toilet or closet auger. It looks like a drain snake and has a cable that rotates by a handle. This should fix things quickly.

4. Faulty toilet handle

If the handle is broken it should be pretty obvious this is the issue. All that’s happened is that it has become disconnected and is quick and easy to fix. Look inside the tank and see if the handle is still connected to the little arm and chain that lifts the flapper. You may just need to reconnect a couple of basic parts such as a broken link in the chain or a loose nut.

5. A drain line problem

If all else fails, it could be the drain line. This pipework moves waste to the sewer or septic tank and if other drains in the house are also not rinsing properly – the bathroom or kitchen sink, shower, bath – then it’s likely to be a drain line issue. Your plumber should be able to use an extra-long auger to clean it out. In some cases, trees and other roots can creep into drain lines and cause issues, which will require more specialist help.

How can I force my toilet to flush?

Take a bucket of water and pour slowly into the toilet bowl. Speed up gradually and the water should push the waste in the bowl through the pipes, allowing you to flush the toilet in the usual way.

How much do plumbers usually charge per hour?

If you need to call the experts in, a plumber usually charges between $45 and $200 per hour. Any small repairs don’t tend to need a permit to complete the job.

Hayley Gilbert
Hayley Gilbert

Hayley is an interiors journalist, content provider and copywriter with 26 years experience who has contributed to a wide range of consumer magazines, trade titles, newspapers, blogs and online content. Specialising in kitchens and bathrooms, she has twice won the CEDIA Award for Best Technology feature. Hayley writes for H&G about kitchens, bathrooms, cleaning, DIY and organizing.