How to Stop a Running Toilet (5 Causes and Fixes)

A running toilet is one of the most common household problems. Not only is the sound annoying, but it can also result in a hefty water bill too. So what are the causes?

To identify the cause of a running toilet, you should first inspect the valve, fill tube, fill height, handle and flapper chains, and the flapper level.

This guide is going to help you identify which of the 5 reasons is causing the issue, with an in-depth guide on how to remedy the situation.

5 Fixes for a Toilet That Won’t Stop Running

A typical reaction to a toilet that will not stop running is to slap the side of the tank, but this rarely works, and it will not tell you where the problem is. Often the problem will get worse, and you may find that it starts running when you are asleep, which can lead to wasted water and large bills.

1. Check the Valve

A common cause for a running toilet is a broken fill valve, where the cistern controls the flow of water into the tank. The valve will have a small rubber insert that will press against a water inlet once the tank fills up.

This valve is connected to the ballcock or float so that you can set the amount of water that the tank stores. There will also be an overflow pipe to stop the water from flooding your bathroom if the valve doesn’t work.

If the rubber insert is old and crusted over with scale or the inlet jet is dirty, the seal will be imperfect and unable to stop the water. In some cases, these valves can crack with age, or the plastic pins that hold the valve flat to the jet wear out and become loose.

You can sometimes see that water is shooting out of the side of the valve, even when the water has reached the top. Another clear sign is the water reaching the top of the cistern’s overflow pipe and continuing to run into the toilet bowl.

The Fix

You may be able to clean off any sediment build-up on the rubber seal. If you feel that removing the valve is too involved, now is the time to call a plumber, or you can follow the below steps:

  1. Turf off Water – There will be a small tap next to the toilet that controls the flow to the cistern. Turn off the water by twisting the handle clockwise. Turn the valve until it is tight, do not overtighten as the handles on these small taps are easy to break.
  2. Flush – Empty all the water in the tank by flushing the toilet.
  3. Remove – Take the old fill valve out (some valves twist out anticlockwise). You should be able to see if the valve clips or twists into the base of the cistern.
  4. Disconnect – You will need to remove the hose that leads into the cistern. Have a bucket ready to collect the water in the hose.
  5. Shop – Take the old valve to a DIY or plumbing shop and ask for a replacement. The replacement valve may be a different brand, but the fitting and size should be standard.
  6. Install – Install the new replacement valve.
  7. Reconnect – Reconnect the hose to the cistern and turn the water back on.

2. Check the Fill Tube

Some toilets use a fill tube to direct the water away from the float as it enters the tank to reduce noise and splashing. As these tubes age and clog with sediment, the water flow will go from running smoothly to spraying all over the inside of the tank. This may cause some of the water to enter the overflow pipe as the tank is trying to fill.

The fill tube may have also moved and shifted to release water directly into the overflow pipe rather than into the tank. Fill tube problems can also cause the tank to take longer to refill or for there to be insufficient water to flush.

The Fix

Take the lid of the tank and inspect the fill tube for damage and blockages. You can separate the tube from the rest of the valve if you need to, but you should be able to inspect it in place. Make sure that the end of the tube is pointing down to the base of the tank to reduce splashing. And check that the nozzle is away from the overflow pipe.

3. Check the Fill Height

A ballcock or float controls the fill height in the tank by shutting off the water supply to the cistern. The overflow pipe will allow water to escape back into the toilet bowl if the float is set up wrong or something in the tank is broken. The overflow pipe, like the ballcock or the float, is also adjustable and should be set a couple of inches above the height the float is set at.

A common mistake with a new toilet is to not adjust the overflow pipe, leaving it below the highest level of the float. This would mean that the tank never fills to the height intended, and water will continue to flow back into the bowl. You will also notice that even though there seems to be plenty of water in the tank, it is not enough to make a complete flush.

The Fix

With a new cistern, you will find that everything is set to the lowest setting, including the overflow pipe. Once you have adjusted the ballcock or the float to the preferred level, you need to check that the overflow pipe sits above the overflow.

4. Check the Handle and Flapper Chain

The flapper stops water from escaping into your toilet bowl as the tank fills with water. When you pull the chain or push down on the handle or button, the flapper opens to release the water into the toilet bowl. The flapper relies on a perfect seal, but over time the rubber will wear, crack, and leak water into the bowl.

You can test to see if the flapper is damaged with the following steps.

  1. First, check that water is not flowing into the overflow pipe.
  2. Add some food coloring to the tank.
  3. Wait 30 minutes.
  4. Check the toilet bowl to see if the food coloring made it to the bowl without flushing and if the water is coming from the flapper.

The Fix

If you have a chain-style toilet, check that the chain is not lifting the flapper and allowing water to seep through. It may be a simple case of the chain and the handle being too heavy. For all toilets, you also need to check that the flapper does not get stuck open after a flush due to an obstruction around the flapper seal. And check that both the handle and the flapper can move freely.

If you need to remove the flapper, you can use these simple directions:

  1. Turn the water off at the stopcock that leads to the toilet, twisting it counterclockwise.
  2. Flush the remaining water out of the tank.
  3. Remove the flapper will hinge on two plastic pins. Carefully lift away the edge of the flapper from the pins to release it.
  4. Disconnect the chain that leads to the flush mechanism.
  5. Replace and install the new float and reattach the chain.
  6. Turn the stopcock valve clockwise and wait for the tank to fill.
  7. Test and add some more food coloring to the water in the tank to test that your new flapper is working.

5. Check the Float Level

The float level can be another reason for water escaping into your toilet’s overflow pipe. Test the valve first by lifting the ballcock or float to shut off the water supply. If the flow stops, the valve is fine, and you need to check the float. Every cistern will have a float in the form of a ball on the end of an arm or a vertical foam float.

Floating foam blocks are more common in modern cisterns. These foam blocks ride along the pipe that supports the valve. In both cases, you can adjust the float’s position to reduce or increase the amount of water that the tank stores.

If the foam block or ballcock is set too high, there will not be enough pressure to seal the valve to stop water from filling the tank. But if you set the float too low, there may not be enough water in the tank to flush everything away. And over many years, the float may have degraded, taken on water, and sunk by itself.

The Fix

If your cistern uses a float on a metal arm, the metal may be bent out of position or twisted. You will see the watermark on the back of the cistern. Assume that the water level is around an inch below the water mark, which should also be below the overflow tube.

You can twist the ball on the arm to change the height that it sits at in the water. Shortening the arm will raise the water level in the tank. If you raise the height of the ballcock, wait for it to continue filling to ensure that it stops lower enough beneath the overflow pipe. If you are lowering the ballcock, you will need to test the water in the tank to see if there is enough left to make a complete flush.

So how do you fix a running toilet without a ball float? For a vertical float, you will find that you can twist the float or the pipe that it travels on to change the fill limit. The same process of testing applies to a ballcock as with a vertical float.

Joshua Milton

I want to share everything I know about home improvement in order to help you. Whether you're a home enthusiast or an industry professional, I have the information that you need.

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