Repair when Not in Use

Prevent flooding - Ensure proper adjustment

This article will explain the importance of both the flush valve and fill valve, along with a diagram showing the placement and height requirements needed to build a safe toilet.

The Importance of the Flush Valve

The most important safety feature in a toilet is the flush valve overflow pipe.

  1. The overflow pipe is critical because it is a defense against water exiting the toilet tank.
  2. Plumbing codes require toilets to be equipped with overflow protection of sufficient size to prevent tank flooding at the maximum rate at which the tank is supplied with water under normal operating conditions.
  3. In the event the toilet fill valve does not completely shut off at the end of a flush cycle, the overflow pipe is designed to transfer the water from the toilet tank to the toilet bowl and out the drain line.
  4. Preventing water from exiting the tank can beachieved through proper height adjustment of the overflow pipe.
  5. Fluidmaster instructs setting the height of the overflow pipe at least 1 inch below the opening of the tank lever.
  6. In most applications it will be necessary to cut the overflow pipe to achieve a proper fit.

The Importance of the Fill Valve

  1. Proper height of the fill valve in relation to the overflow pipe will ensure the toilet cannot siphon water from the tank back into the water supply.
  2. Proper fill valve height also allows for proper water level in the tank and bowl.
  3. Critical Level Mark (Indicated with the letters CL on the fill valve) of the fill valve must be 1 inch above the top of the overflow pipe.
  4. When the fill valve height is set correctly it is possible for the top of the valve to be positioned above the rim of the tank.
  5. This is normal in most applications and will still allow the tank lid to fit properly on the toilet tank.

Placement and Height Requirements Needed for a Safe Toilet


To download our free guide to fix common toilet problems please click here: Fluidmaster Toilet Repair Guide