Why Does My Toilet Keep Running?

411 plumb A toilet can keep running for two reasons either of which can easily be seen by removing the lid from the tank. I would suggest that you put the lid on the floor while you look because toilet tank lids can be very expensive and sometimes almost impossible to get replacements. The water running is either the fill valve or, ballcock as we call them in the plumbing trade, is not shutting off and water is running over the top of the overflow tube or, the water is leaking past the flapper.

If you see water running over the top of the overflow tube the fill valve the fill valve has either failed or, it is not adjusted properly. You can try to adjust it to maintain the water level at the water level marked on the tank or overflow tube if there is a mark or, 5/8” below the top of the overflow tube. If once adjusted the fill valve cannot maintain the level but continues to allow the water level to rise above the top of the overflow the fill valve or, ballcock should be replaced. In many cases a Fluidmaster 400A is an ideal replacement.

If the water is not going over the top of the overflow tube but the water level drops down and the fill valve or, ballcock turns on to replenish the tank water level then the problem is water getting past the flapper. In most cases replacing the flapper with a new flapper of the proper type for your toilet, installed properly will solve the problem however, in some cases there may be other problems allowing the leakage.

  • If the bowl refill tube from the fill valve to the overflow tube is inserted into the overflow tube below the water level in the tank it can siphon water from the tank down into the overflow tube. The refill tube should clip onto the overflow tube above the top of the overflow tube.
  • On some toilets the rubber gasket below the flush valve can deteriorate from chemicals in the water and ripple up causing interference, which keeps the flapper from seating properly. I have frequently seen this on Kohler toilets and in most cases was able to trim off the ripples in the rubber gasket with a single edge razor blade allowing the flapper to seat properly.
  • The flapper chain being too tight can cause the flapper to leak. The chain should have slack then the handle is released and the flapper seated.
  • Check the flapper chain hook’s position on the tank lever to make sure the hook does not run a risk of catching additional links on the flapper chain when running through the flush cycle. Move the hooks position as required to prevent problems.
  • Excess flapper chain landing under the flapper can cause the not to seat properly. The excess chain should be cut off and thrown away. I usually just leave about 3 extra links just in case additional adjustment is needed.
  • Problems with the handle and tank lever causing inconsistencies in the chain tightness can cause the chain to be too tight at times causing leakage, the handle and tank lever should move smoothly and not stick or bind if it doesn’t replace the handle and tank lever. Sometimes the mount may be loose in the hole in the toilet tank allowing the position of the tank lever to vary. If this is happening keep the tank lever in it highest possible resting position when adjusting the flapper chain slack. When you do this procedure the chain can never become too tight causing leakage.

A leaking toilet can waste huge amounts of water everyday without you even realizing it because it runs right through the toilet and down the drain without you ever seeing a puddle of water. You can easily be wasting as much as two hundred gallons of water a day and never know it until you get your water bill. A $5 flapper or, $10 fill valve is cheap compared to what three months of a toilet pouring two hundred gallons of water a day down the drain could cost.