There are a variety of reasons why a toilet could keep running, however the following are some of the more common ones:
The rubber flapper valve that controls the flow of water from the tank to the bowl has been worn out and no longer functions properly. If the flapper valve is worn out or damaged and unable to form a tight seal, water may leak frequently into the bowl. This can be prevented by replacing the valve. It's possible that this will lead to an increased water bill in addition to water being wasted. If the flapper valve is broken or cracked, it is recommended that you replace it so that you can identify whether or not it was the cause of the problem.
a broken fill valve: The amount of water that is stored in the tank can be controlled by the fill valve. If the fill valve is broken, it may not be able to control the water level efficiently, which could cause the toilet to run constantly. This could be avoided by replacing the fill valve. You can identify whether or not the fill valve is the source of the problem by inspecting it to see if it is leaking or by observing the water level in the tank to see if it is either too high or too low. If such is the case, replacing the fill valve might be the best course of action.
a lift chain that is obstructed: The flapper valve and the flush handle are both connected to one another by the lift chain. If the chain is clogged for some reason, the flapper valve might not be able to be lifted all the way, which will cause the toilet to run continually. You can check to see if the lift chain is the cause of the problem by inspecting it. If the lift chain is the cause of the problem, it is possible that it would be best to replace the chain or make some adjustments to it.
If the flush handle is damaged or loose, it may not be able to lift the flapper valve adequately, which will cause the toilet to run continually. You can visually inspect the flush handle to see if it is stuck or loose to determine whether or not it is the source of the problem. In that case, it is possible that the flush handle has to be replaced or readjusted.
There is a problem with the plumbing: If none of the issues stated above are occuring, and the toilet is still running, the issue may be with the plumbing in your home, such as a clogged drain or an issue with the main sewage line. It is strongly suggested that a plumber be contacted in order to have the plumbing examined and the problem identified in this scenario.
Fixing a toilet that always runs can assist save money on water bills and also conserve water resources, therefore it is essential to keep this in mind while attempting to fix a running toilet. The majority of the time, an easy do-it-yourself remedy is all that is required to stop a running toilet. However, there are some situations in which it may be best to call a plumber.