Stop Running Toilets

A toilet that runs constantly due to a leak is not only annoying but can be a big waste of water. In fact, a leaky toilet can waste up to 200 gallons of water a day. Toilet leaks are the most common type of leaks at home, so it’s worth taking a few minutes to check your toilets for leaks and repair as needed.

Meet John the Running Toilet

John the running toilet team pic
John, the Running Toilet 2

We’re excited to introduce John the Running Toilet as the newest member of our water conservation team. John will be appearing at home games of the San Rafael Pacifics baseball team throughout the summer as a reminder to save water by finding and fixing toilet leaks. Between innings, kids will have a chance to chase down John in a challenge to stop the running toilet.​

​Testing your toilets for leaks

Check your toilet for leaks by placing a leak detection dye tablet or a few drops of food coloring into the toilet tank. Wait 15 minutes. If you see color in the toilet bowl, you have a leak that needs repair.

Fixing common toilet leaks



Two common toilet leak sites are the overflow pipe and the flapper valve, both located inside the toilet tank.

    toilet diagram
  • Overflow pipe: If the leak is at the overflow pipe, you will see water flowing over the top of the pipe, which means the water level is too high. (Sprinkling talcum powder on the surface of the water makes it easier to spot this leak.) You can adjust the water level in different ways, depending on the type of toilet. Older toilets have a float arm that can be bent down (be careful, or it may break) to adjust the water level so it stops a half-inch below the top of the overflow pipe when refilling. For many newer toilets, the water level can be adjusted by turning a small knob.
  • Flapper valve: If the leak is not at the overflow pipe, the flapper valve is probably the culprit. If the flapper valve appears to be deteriorated or does not seal completely, it should be replaced. You can find a replacement flapper at a local hardware store. Make sure you know your toilet's manufacturer (often written behind the seat hinge, between the seat and the tank) and model number (often a four digit number stamped into the porcelain on the back inside of the toilet tank) before going to buy a replacement. So-called “universal flappers” may fit your toilet, but can cause it to use much more than it was designed to - as much as 5 gallons per flush.
If your toilet still leaks after checking the overflow pipe and the flapper valve, you may need the assistance of a plumber.