How to Adjust a Fluidmaster

Updated June 29, 2018

Toilet tank assemblies need adjustments upon installation and may need minor adjustments after several years of operation. Additional items can cause components to operate inefficiently, like rust and debris in the water line. Pipes that freeze in the winter with no water flow will carry sand, rust or glue particles with the water when it is working again. These items will stop up the water-fill valve. Additional components will eventually wear due to age, including the flapper, causing a toilet to run.

Locate the water-level adjustment clip on the Fluidmaster toilet assembly. Open the toilet tank lid and set aside. A small clip rests on the metal rod or link to the right of the float cup.

Squeeze both sides of the adjustment clip to release its pressure on the link. While squeezing the clip, move it higher or lower to adjust the water level in the tank.

Move the clip up to increase the water level and down to decrease the water level. Release the clip in its new position on the link. The water level will fill to the top of the clip. This adjustment will correct a running toilet with a water level that is too high. If the water level is too high, it will enter the overflow pipe, lower the tank level slightly and cause the valve to refill the tank often.

Check the float ball rod for bends. If the rod is bent, the toilet will run constantly and try to refill itself. Bend the rod gently back into a straight position. This adjustment will also allow the toilet to evacuate the water completely after each flush.

Adjust the float ball so it does not touch the sides or back of the toilet tank when it lowers and rises on top of the water level. If it is touching any object, bend the float ball rod to keep it from rubbing.

Check the flapper in the bottom of the toilet. If the flapper does not seat properly to cover the hole in the bottom of the tank, it will cause the tank to leak continuously. In addition to the toilet leaking from the bottom, it will also fill with water.

Unscrew the top of the fill valve by turning counterclockwise one-eighth of a turn and lifting the top off. Observe inside the fill valve to see if there is any debris travelling into the valve through the water lines.

Straighten out a wire coat hanger and remove any rust or debris from the opening in the fill valve. Invert a small plastic cup over the top opening of the fill valve and flush the toilet several times. This will clear any debris that the valve captures.

Replace the top on the fill valve by placing it on the assembly and turning it clockwise one-eighth of a turn while pressing down.


A slow-filling toilet tank can result from the main water valve not being all the way open. Turn the main water valve at the base of the toilet fully in a counterclockwise direction so that the maximum amount of water can enter the toilet assembly.

Things You'll Need

  • Wire coat hanger
  • Small plastic cup
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About the Author

Mary Lougee has been writing for over 10 years. She holds a Bachelor's Degree with a major in Management and a double minor in accounting and computer science. She loves writing about careers for busy families as well as family oriented planning, meals and activities for all ages.