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Test a Toilet for Leaks

Use this simple test to determine if your toilet flapper is leaking and needs to be replaced.


Step 1

Your toilet gets a lot of use, so normal wear-and-tear results in a lot of maintenance. One of the biggest bathroom issues is a toilet that keeps running after you flush it. If left untreated, this problem can run up your water bill, so you should fix this problem as soon as possible.

These problems are typically rooted in the fill tank. The first issue could be the water level. If the water level is above the overflow pipe, then the fill valve or ballcock isn't working properly or is set to the wrong height. Make sure that the water level is adjusted to the manufacturer's instructons. Be sure to check the flapper. It's usually stamped inside the tank. If the flapper is leaking, it will keep triggering the fill valve to refill the tank.

To see if the flapper is leaking, here is a simple test:

  • Put a few drops of food coloring in the tank. 
  • Let it sit for 25 minutes.
  • If the color leaks into the toilet bowl, then there's a leak.

First, check the flapper to see if sediment or debris has built up around it. If not, replace it. This is typically a lot cheaper and easier to replace than the fill valve.

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