Running toilet from a scaled flapper
Why it happens here
Hard water in the 91765 area leaves mineral deposits on the flapper. The deposit keeps the flapper from sealing, so water runs from the tank to the bowl continuously. It is the most common call we get along the boulevard.
Our approach
We replace the flapper with a Korky or Fluidmaster model that resists scale. We also check the fill valve and flush valve seal for the same buildup. If the valve is scaled, we replace it.