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Toilet Runs On Its Own Ghost Flushing

When the 400A fill valve turns on and off during periods of non-use, it is refilling the tank due to water loss. This is commonly called “Ghost flushing”.

If this is a new installation of a Flush Valve, then try removing the toilet tank and tightening the Flush Valve lock nut ¼ to ½ turn beyond hand tight first, as this is the most common leak on a new installation.

Water Test

  1. Turn the water off at the wall. Do not flush the toilet. Leave the tank full.
  2. Mark the water level with a pencil. (This is for a reference point each time you check the water level of the tank).
  3. Check the tank every hour or so. Each time you check the tank and the water level has dropped from your previous mark, remark the new water level.
  4. Eventually, you will check the tank and the water level will not change from the previous pencil mark, or the tank is empty.

Determining the location of the leak:

  • When the water level has stopped draining and the tank is not empty, the leak is slightly above the surface of the water on the flush valve.
  • If the water level stops at the lower lip of the flapper, you should clean or replace the flapper. The flush valve seat may need to be cleaned as well.
  • If the water level stops anywhere above the flapper, check the refill tube. If the fill tube is shoved deep inside the overflow pipe, and is below the water level of the tank, it will siphon water. Shorten the hose so the end is above the water level of the tank or use the refill clip supplied with the Fluidmaster kit. Refill clips and new refill tubes are available at most hardware stores. If the water drops below the flapper and seat, check the tank for cracks as well as the condition of the spud gasket (rubber washer under drain seat). The Flush valve should be replaced or repaired.