If you've tried replacing the toilet flapper but the toilet still runs, the flush valve seat is probably rough or pitted. You can replace the entire flush toilet flapper valve, but it's a big job.
A chain that's too short or tangled won't allow the flapper to close and water will continue to leak into the bowl. This causes the fill valve to cycle on and off to refill the tank. A chain that's too long, or a flush rod that hits the tank lid, won't open the flapper wide enough to stay open for the full flush.
Will a running toilet stop eventually? As fresh water enters the tank, a mechanism eventually shuts off the water flow and the toilet will stop running. However, when things go wrong with the valve, flapper or overflow then it's best to get it sorted.
Adjust the chain
You don't want the chain too short or it will constantly pull the flapper up and allow water to leak into the bowl. You also don't want to leave the chain too long or it will not be able to pull the flapper open all the way when you flush. You may need to adjust it several times to get it JUST right.
With a simple adjustment of your toilet flapper, this is quickly resolved. If your toilet is flushing twice, it is most likely due to the fact that it is staying open too long and flushing too much water. If you have an adjustable flapper, this can be corrected by adjusting your toilet flapper to close quicker.
A chain float helps the flapper stay open a bit longer, allowing more water to enter the bowl for a better flush. You can adjust the float up or down on the chain to fine-tune how long the flapper remains open. Get a stronger flush—and a lower water bill. Find out how to fix things if your toilet keeps running.
Among the most common problems for a running toilet is caused by a fill valve issue. This is when the water level is too high and water spills out of the top tank and into the overflow tube then down into the toilet bowl. This happens when there is excess water in the top tank.
Usually this is caused by one of the following problems: The water level in the tank may be at or above the top of the overflow pipe. The flapper or stopper ball that closes off the outlet at the bottom of the tank may be defective. The fill valve may need replacing.
If your Fluidmaster fill valve is not shutting off all the way or not filling quickly like it did when it was new, then replacing or cleaning the fill valve seal will most likely fix the problem.
Wipe up any water left inside the tank with a sponge. Lift the flapper and prop it against the overflow tube. Apply a light coat of Vaseline around the rim of the flush valve opening. Lower the flapper and restore the water supply by opening the supply valve.
A dirty flapper can cause a leak due to algae or other minerals not allowing the flapper to properly close. If the flapper is dried out, warped, cracked, or pitted, then you'll need to replace it. Check for cracks in the flush valve (the piece the toilet flapper seals against).
While toilet flappers are normally pretty durable, they can wear out over time. The average toilet flapper lasts about 4 to 5 years. It is important that you replace your toilet flapper when needed to prevent damaging leaks.
While flappers are simple devices, they are not indestructible. Over time, the flapper can warp, crack, or break. If it does, it is no longer able to control water flow between the tank and bowl. Accordingly, water often leaks from the tank into the bowl, creating an annoying, trickling sound.
An overflowing toilet is caused by one of three things: a clogged or blocked drain that doesn't allow for a proper flush, an improperly adjusted float that allows the tank to overfill or a blocked vent pipe that replaces the air in the pipe after each flush.
If the water level is too low, you may end up with frequent clogs because there isn't enough water to properly flush the toilet. If it's too high, your toilet could become dangerously close to overflowing every time you flush.
A universal sized toilet flapper used to be the norm, but today toilet flappers can range anywhere from 2″ to 4″ in size. The size of the flapper that your toilet uses usually is determined by a couple of factors. More recently manufactured toilets tend to use 3″ or 4″ flappers, as opposed to 2″ flappers.
Even a small leak in your toilet can cause it to constantly run. Check the base of the toilet, the water supply line, and the tank for any signs of water. If you notice a leak, you may need to tighten a connection or replace a seal. Then check the water level in the tank to see if it's too high or too low.
It is possible for dirt and debris to lodge itself inside the valve. This can happen any time the water is on and may happen after a new installation, a few days later or even months and years after installation.