Over time, a toilet can develop issues, including continuously running water, which can significantly increase your water bill and wastewater.
The good news is that the issue of a toilet constantly running is often easy to identify and can usually be fixed without calling a plumber. With a bit of time and the right tools, you can fix your toilet and save money on your water bill.
Common reasons for a constantly running toilet tank or bowl
A constantly running toilet is typically caused by one of a few key issues within the toilet tank. Understanding how the toilet works will help you troubleshoot the problem and identify which part needs repair or replacement.
The most common culprits include the overflow tube, flush valve, and fill valve, all of which play essential roles in the toilet’s water management system.
Faulty overflow tube
The overflow tube is part of the flush valve assembly and is responsible for directing excess water from the toilet tank into the bowl, preventing overflows.
If the overflow tube is too short or damaged, water will continuously flow into the toilet bowl, causing the toilet to run without stopping. This issue is especially common if the current flush valve assembly isn’t compatible with your toilet or if the tube was cut too short during installation.
When the overflow tube is at the incorrect height, it will fail to regulate the water level properly, leading to water constantly flowing into the toilet bowl. The solution may involve adjusting the height of the tube or replacing the flush valve assembly with a compatible one.
If the overflow tube is in good condition and at the correct height, the issue might be with the tank's water level or the fill valve.
Worn toilet flush valve
The flush valve is responsible for releasing water from the tank into the bowl during a flush. Over time, the flush valve can become worn, or the flapper attached to it may lose its ability to seal properly. When this happens, water will leak through the flush valve even when the toilet isn’t being used, leading to a constantly running toilet.
If the flush valve is worn out or damaged, it won’t close properly after a flush, allowing water to continuously escape into the toilet bowl.
This constant flow of water not only wastes water but can also prevent the tank from refilling fully, causing poor flush performance. Replacing the flush valve or flapper with new components will usually solve this problem and restore normal function to your toilet.
Faulty fill valve
The fill valve controls the water level in the toilet tank by regulating the flow of water into the tank after each flush. If the fill valve becomes faulty or misaligned, water can continue to flow into the tank, eventually spilling into the overflow tube.
This constant refilling cycle can waste large amounts of water, driving up your water bill and leaving you with a constantly running toilet.
The fill valve is typically easy to replace and should be adjusted to ensure the water level in the tank stays about an inch below the top of the overflow tube.
If the water continues to rise past this point, even after adjusting the float mechanism, then it's likely time to replace the old fill valve with a new one.
What you'll need
Before starting your toilet repair, grab any tools and materials you might need. Having everything ready will help you complete the job quickly and efficiently without any unnecessary interruptions.
Materials
- Float
- Flapper
- Flush valve
- Fill valve
- Flush valve chain
Tools
- Channel locks
- Screwdriver
- Bucket
- Towel/cloth/sponge
How to fix a running toilet
Step 1: Check the overflow tube height
Start by removing the tank lid and inspecting the overflow tube. The tube should be tall enough to prevent water from constantly flowing into the toilet bowl.
If the tube is too short or has been cut improperly, it will need to be replaced with a flush valve assembly that fits correctly in your toilet tank. If the overflow tube is at the correct height, check the water level in the tank.
Step 2: Lower the water level in the tank
If the water level in the toilet tank is too high, it may be flowing into the overflow tube, causing the constant running sound. Ideally, the water level should be about an inch below the top of the overflow tube. Adjust the float rod, float cup, or float ball to lower the water level to the desired height.
To do this, locate the adjustment screw on the fill valve and turn it counterclockwise with a screwdriver or channel locks.
Make small adjustments until the float is set correctly. If the float is damaged or waterlogged, replace it with a new float to ensure the fill valve works properly.
Step 3: Inspect the flush valve chain
Next, inspect the flush valve chain that connects the flush lever to the flapper. If the chain is too short, it won’t allow the flapper to close properly, causing a steady stream of water to flow through the toilet.
Conversely, if the chain is too long, it can become trapped under the flapper, preventing it from forming a proper seal.
Make sure the chain is the correct length to allow the flapper to close completely. You can remove excess links from the chain or replace them with a flush valve chain of the correct length.
Step 4: Check the flapper
The flapper, usually made of rubber, can wear out over time or become warped. A damaged or worn flapper won’t seal the flush valve properly, allowing water to continuously flow into the bowl. Remove the rubber flapper and inspect it for any signs of wear, warping, or grime.
If the flapper is damaged, replace it with a new flapper. If it’s just dirty, clean it with warm water and vinegar to remove any debris, and then reinstall it to ensure a proper seal.
Step 5: Replace the flush valve
If adjusting the overflow tube and inspecting the flapper doesn’t stop the water from running, it may be time to replace the entire flush valve assembly.
Start by turning off the toilet's water supply and flushing it to empty the tank. Remove the tank-to-bowl bolts and carefully lift the tank off the toilet bowl.
Loosen the flush valve nut, remove the old flush valve, and install the new flush valve assembly.
Reattach the tank-to-bowl gasket, secure the tank bolts, and reconnect the water supply. Turn the water back on and test for leaks.
Step 6: Replace the toilet fill valve
If the overflow tube and water level are correct, but the toilet continues to run, the fill valve may be faulty. To replace the fill valve, turn off the water supply and flush the toilet to drain the tank.
Disconnect the water supply line and remove the old fill valve by unscrewing the locking nut underneath the tank.
Install the new fill valve and adjust the height to the correct level. Tighten the locking nut, reconnect the water supply line, and turn the water back on.
Ensure there are no leaks and that the fill valve stops the water flow when the tank is full.
When to call in a JustFix professional
If these steps seem too complex or you’re unsure about handling the repair, it’s always best to call in a professional plumber. At JustFix, our team of skilled plumbers can quickly diagnose and fix a running toilet, ensuring the job is done right the first time.
We offer convenient, next-day service to get your toilet back in working order without delay. Let us handle the hard work, so you can avoid the frustration of dealing with a constantly running toilet.
If you're dealing with other issues, like a toilet cistern not filling or a badly blocked toilet, our comprehensive guides offer solutions.
