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Fluidmaster Fix It Zone


Water Leaking From The Bottom Of Toilet Tank

  1. Constant leaking means the locknut is not tight enough, the rubber washer inside the tank has flashing or the porcelain surface inside tank is uneven or has a chip, therefore not sealing.
    1. Get out your pipe wrench and tighten the locknut 1/4 turn more, dry the area and then check for leaking. If the leaking stops then don’t tighten any more. If this reduces the leaking then go 1/4turn more and check again. If this still does not seal it then do not tighten anymore. Go back and check the parts and gasket for any signs of improper fitting, flashing (excessive rubber), or cracks in flush valve threads or in porcelain surface.
    2. Check the rubber washer in the tank for flashing (excessive rubber) or improper contact with flush valve and tank. There may be a chip in the porcelain tank or dirt and debris around thesurface opening. Clean the bottom of the tank. You can sand and/or file the porcelain surface to remove bumps and ridges. Re-install the lock nut, if the leak persists, use silicone sealant on the underside of the rubber washer to stop the leak. DO NOT USE PLUMBER’S PUTTY.
  2. Leaks occur when you flush the tank, the problem is the Tank to Bowl Gasket.
    1. Make sure the tank and bowl are touching the “Ridge”. The ridge is about ¼” higher porcelainon either the tank or bowl surface that the other rests on for stability. Tighten the wing nuts down until the tank and bowl touch. Place the sponge rubber gasket from your Fluidmaster kitover the nut before placing tank on to bowl, see example A. 

      "5403" 3 universal flapper by Fluidmaster
      Example A

      Some models of toilet do not have a ridge, but use rubber support spacers for stability, see example B below. The lock nut goes on after the triangular gasket is placed on tank.

      "5403" 3 universal flapper by Fluidmaster
      Example B

      A third type of tank to bowl connection does not have a ridge nor does it use rubber supports at the bolts. This type seals by the gasket and supports the tank by the tank to bowl gasket.

    2. You may have a toilet that requires a larger or smaller gasket in order to seal the tank to the bowl. Compare the tank to bowl gasket in the kit to the relative shape, size and density to the gasket you took out? If they are similar or the same proceed further. If not, purchase the correct sponge gasket to finish the job. For example: some Gerber toilets use an extra thick gasket. It is helpful if you know who manufactured your toilet. You may even want to call them to confirm the correct thickness of gasket required by your toilet.
    3. "5403" 3 universal flapper by Fluidmaster
      Examples of common tank to bowl gaskets