How To Test For Toilet Leaks

Toilet leaks can waste as much as 4 to 5 gallons of water per minute and significantly increase your monthly water bill.


One of the most common toilet leaks, and often hardest to detect, is caused by a deteriorated or defective flush valve (flapper) ball at the bottom of the toilet tank.  If the flapper or ball valve does not seat properly and form a watertight seal, water will leak around it and flow into the toilet bowl.  This type of leak can be occur without any detectable sound.  To test for this type of leak:


  • Remove the tank lid
  • Place several drops of red or green food coloring or a dye tablet inside the tank
  • Replace the tank lid and check the next morning (do not flush during this time)
  • If any trace of the color appears in the bowl there is a leak



Another common toilet malfunction that can use an excessive amount of water happens when your toilet does not shut off promptly after the tank fills.  Do not walk out of the room and assume this is happening.  Watch and listen for several minutes after flushing each toilet to detect any prolonged flow. 


Toilets that are not used frequently, such as those in spare bedrooms or other unoccupied areas of the residence, can develop leaks and run for long periods of time without your knowledge.  Don’t forget to check those frequently!