Plumbing in the Home/toilet running


QUESTION: Approximately one year ago, we purchased a home (built in 1991). One of the baths has a 1.6 GPF Kohler toilet. Recently, I noticed that I would hear the toilet run about once every hour or so for approximately three seconds refill the tank. My first step was to replace the flapper. When this didn't resolve the problem, I replaced the fill valve with the identical model that was already installed (fluidmaster 400 anti-siphon). I adjusted the new fill valve to ensure that the water level was at the appropriate mark on the side of the overflow tube. The new fill valve has improved the problem, but I still notice that once every hour or so, the toilet will run, but this time only for about one second. I have tried adjusting the valve to lower the water level, but this does not fix the problem. I have now tried everything I know to do. Are there any other areas I should check before calling a plumber?



ANSWER: Hi Michael,
This phantom flush is usually a bad seal on the flapper causing the level to go down in the tank. You can verify this by putting a bit of food dye in the tank and then checking if it made it into the bowl after a time of non-use.  
If it has,
1. the flapper may not be sealing properly for some reason.
2. the ring that the flapper seals against may be damaged or have a build up of minerals or debris. Can be cleaned with a scotch brite pad if not badly damaged.
Good Luck,

---------- FOLLOW-UP ----------

QUESTION: Thank you Dana. I tried the food dye experiment and the colored water did indeed make its way into the tank. I replaced the flapper several months ago as a first step to solve the problem. I checked the flapper again and it appears to be intact and had no deposits on it. The plastic ring that the flapper seals against also appeared to be free of deposits and I felt no chips or cracks that would prevent a tight seal. I cleaned it as a precaution, but I am still experiencing the same problem with intermittent running of the fill valve for a second or two about every hour.

The new flapper I installed was universal, and it appears to fit the opening. Would you recommend trying a different type of flapper, or is there another solution I can try?

Thank you very much for your help.

Best regards,


Hi Michael,
If the dye is getting into the bowl, the flapper is not sealing and the tank level is going down triggering the refill.  "Universal" is like "average" of the worst and worst of the best! LOL  
I would try a different one.  Fluid Master makes a flapper replacement/repair kit as well. That might work better.
Good Luck,

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Dana Bostick


Pretty much any residential plumbing questions. For "item specific" details such as a specific model of fixture, I will need to research and there may not be any useful information available. Note: I live and work in Southern California. We do not, as a rule, use hot water or steam heating systems, oil fired boilers or private water wells so my knowledge in those areas is pretty limited. There are others here on AllExerts that can probably answer those questions better.


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