How to Stop a Constantly Running Toilet

Homeowners with older houses often ask how they can stop a constantly running toilet. There are a couple of simple causes with equally simple fixes.

It may be that the flapper isn’t sealing correctly or that the fill valve is improperly adjusted. If the flapper is warped or damaged it’s pretty easy to replace. First, turn off the water supply and empty the tank. Then disconnect the flapper from the flush chain and unsnap it from the flush tower. Snap on a new flapper and re-connect the chain before turning back on the water.

If water is constantly running down the overflow tube, the fill valve needs to be adjusted. Turning the adjustment screw on the valve in one direction raises the water level and the other direction lowers it. The ideal level for a toilet tank is about an inch below the top of the overflow tube.

These simple repairs should stop the constant flow of water through the toilet. But if you really want to save money on your water bill you should probably consider replacing that old toilet with a new one. Some older toilets use as much as 3 and a half gallons of water per flush, while the law requires newer models to operate with a maximum of 1.6 gallons.


  1. I wish I would have seen this before I called a plumber! I will be checking this website from now on so I can do it myself. Plumbing problems are always scary for me to fix myself but your videos are very informative. I’ll checkout first from now on! Thanks!

  2. Following this video, I changed the flap in the toilet with no problem, but I had to hold the the handle for a complete flush. I kept flushing in hopes of see what the problem was. So, I Googled the phrase “changed toilet flap, now toilet won’t fully flush.” One website said to adjust the flap chain making it shorter until you get a full flush. After a several adjustments, it worked! I’m saying this to say it was left out of the video. Who knew it was an important point or that my replacement flap came with a longer chain.

  3. That is great if you have a ball type. If you have the type where the float goes up and down the tube, there is no screw. What do you do then?

  4. I have a problem with a portion of the toilet paper coming back after flushing is completed, needing a second flush. Upstairs bathroom works fine, since they share the same waste line, there isn’t an obstruction in the line. Is there a simple solution to this problem?

  5. My toilet is constantly making a flushing sound even though I am not using it, it happens specifically frequent in the early AM, like every 5 to 10 minutes. I look at the tank when the flushing sound happen, I see water is sitting very still in it, what could be the reason or problem? Thanks.

  6. My husband and I tried to fix a running toilet. We followed videos and changed flapper and water fill valve. After flushing, toilet stops running but water is still running slowly into the toilet bowl. Is there something we can do or is it time to get a new toilet?

  7. great advice except your picture does not align with advice about turning the adjustment screw, what is the advice for the pic listed about adjusting the fill valve?

  8. Can’t see a screw. My unit has a plastic cap that I cannot figure out how to remove. I am afraid it will break if I try to force it off

    • Hi, Alisha! If water is constantly overflowing, there’s either a toilet or a plumbing problem. This could be due to many different causes, so please contact a plumber if the problem persists.
      Good luck!

  9. I know why the toliet keeps running the small hole on the top of the float is clogged with hard water deposits. It is clogged with hard water deposits. I have used vinegar to unclogged it with some vinegar but it still requires me to to empty the tank and soak the entire tank…so I have done that, but now it’s filled with the tank with small bits of deposits and I can’t seem to get them all out. Any suggestions?

    • Hi, Sherri,
      Danny says, “It might surprise you to learn that you can replace every piece inside the tank with a Fluidmaster repair kit for less than $20. I would recommend you to check it out!”

  10. There are so many questions on your website but you do not answer the specific question/question so why do have a website.? Just so a person can ask a question???

    • Hi, Lois!
      Selected questions will receive a moderator’s answer on the same page. (Just like you see here. :D)
      It’s not possible to answer all the questions we receive, due to the high volume, but we sure do our best!
      Thanks for your question.


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