My toilet is filling very slowly. Sometimes it sounds like it is filling up a drip at a time. What's wrong with it and how do I fix it?

3 Answers 3


Some Fluidmaster valves can't simply be unscrewed, here are my steps for cleaning the ones I have experience with:

  • Shutoff the water to the toilet.
  • Flush the toilet to empty the tank (doesn't have to be completely empty, but you want some working space).
  • Open the valve by lifting the float to the top position, pressing down on the black plastic cap that covers the valve, and giving it a 1/8 to 1/4 turn. You should then be able to lift the cap directly off.
  • Clean sediment or other buildup off any small components of the valve, and if anything is easily detached, remove it temporarily for the next step. Be sure to check inside of the cap where the lever is attached.
  • While the cap is off, place a cup over the top of the valve and open the water supply for a few 5 second bursts. The cup prevents a small geyser from appearing in your bathroom and the water will drain into the toilet tank (this is why you flushed it earlier). This process will clear any sediment out of the valve and supply line, including any sediment that may break free from the toilet shutoff valve.
  • With the water shutoff again, reassemble the valve, and attach it in the reverse process (lifting the lever on the float allows you to turn the cap with a little downward pressure on the cap).
  • Let's all agree that Fluidmaster has simplified this issue a great deal. Worth every penny. By the way, did you know Fluidmaster was started by the same guy that started Kwikset? He understood something, heh.
    – Tim Quinn
    Nov 29, 2012 at 23:47

So having done this myself, I spent the money and bought a new Fluidmaster valve. After replacing the valve and connecting everything the toilet was still not functional. Turns out the problem was the flushing of the pipes was not good enough, the Fluidmaster had to be flushed. I flushed a gallon replacing it, and that simply was not enough.

  1. Turn off the water.
  2. Unscrew the cap on the Fluidmaster valve
  3. cover the top with a cup
  4. Turn on the water and allow it to spray into the cup until the water is clear, then wait 5 more seconds.

You could buy a new Fluidmaster. They are only $8.00. If you are worried about it happening again, get a whole house water filtration system and repipe your house.

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