Repair when Refilling


Toilet Tank Won't Fill Up Or Is Slow To Fill

The main reason for a toilet tank not filling or filling slowly is due to the toilet fill valve. The most common reasons for the fill valve to slow down or no longer fill the tank after the flush are debris issues and the length of time a fill valve has been in use.

Debris that builds up over time inside the water system, including the valve body, supply line or shut off valve (at the wall) can restrict the flow path of water and slow down the valves filling speed.

Toilet fill valves in use for a period of 7 years or more can have their working parts start to wear out.

1. Read more for instructions on how to flush debris from your water supply or watch our instructional video:

2. You can also read more below if you are looking for repair parts or replacement valves.

Flushing debris from your water supply:

Fluidmaster recommends flushing debris out of the valve / water system first in order to resolve the issue.

Steps for removing the top cap and flushing out debris from the fill valve:

  1. Turn off water supply and flush the tank.
  2. Reach inside the tank with your right hand under the float cup and lift it up. With your right hand hold onto the gray shaft keeping the float cup all the way up. Do not allow the float cup to drop or valve shaft to turn.
  3. Place your left hand on the top of the valve cap and while placing your left hand thumb on the side of the arm coming out of the top. Turn the cap and lever counter clockwise 1/8th of a turn to unlock. You should be able to lift off the cap and lever from the valve body.
  4. Once the cap assembly has been removed inspect for debris on the seal (rubber disc with pin coming through) and also the valve portion still in the tank.
  5. Hold a cup upside down over the exposed opening of the valve and turn on the water supply full force for 10-15 seconds, allowing the pressure to free any debris inside the valve inlet.
  6. Reassemble the top of the valve by placing the cap arm next to the refill tube. To lock, press the cap down while turning it and the arm clockwise.

The bottom hand is lifting up on the float cup, which raises the black arm under the top cap. The top hand is gripping the cap while the thumb is pressing on the raised lever arm.

Here is a video on how to remove and replace cap assembly of the 400A fill valve:

2. Repair parts and replacement toilet fil valves:

When flushing debris does not seem to correct the next step is to repair or replace the valve. Fluidmaster Repair Parts and Fill Valves are available at most local retailers and we recommend genuine replacement parts. Repair Models sold:

Replacement Parts recommended:

Replacement Valves recommended:

If you need to replace any of the toilet parts, why not get Fluidmaster’s Everything Kit includes everything you need to fix your toilet in one purchase?

If you are in the U.S. and have a 2″ flush valve toilet, we recommend the 2″ Everything Kit

If you are in the U.S. and have a 3″ flush valve toilet, we recommend the 3″ Everything Kit

If you are in Canada and have a 2″ flush valve toilet, we recommend the 2″ Everything Kit

If you are in Canada and have a 3″ flush valve toilet, we recommend both the 540AKR Flush Valve and the 400H Fill Valve