How to Replace Bathroom Toilet Bowl Fill Valve

Fig.1 Toilet stop valve

By Gary Boutin

Supplies and Tools: 

Dry towels

Fluidmaster® Toilet Bowl Fill Valve 

Water pail

Sometime ago, Mr. Emmet James called me to see if I could repair his toilet. I asked him what was wrong with it. He stated the the toilet was running all over the house. It's an old joke, but toilets do run and then use up lots of water which adds to your monthly bill. A leaky toilet can waste as much as 200 gallons or 260 liters of water a day and that could be as much as $50 in a month. 

This post shows five steps on replacing a toilet bowl fill valve. 

Step 1: Upper right fig.1 shows the stop valve needs to be turned off. This stop valve does not have any fill lines or copper tubes coming from it, but if the water was turned on it would flow and flood the bathroom.
Step 2: Fig.2 shows the toilet bowl fill valve place a  water pail underneath the toilet fill line. This is done to prevent water from leaking on the floor. Now, unscrew the old water fill valve and place it in the trash can. 

Fig.2 Toilet bowl 
fill line

Step 3: Fig.3 shows once the old valve is removed, pull apart the carton box that the Fluidmaster® is in and get to the parts. The parts are all together and sealed so you need to take them apart to get to the valve seal. The black seal is the one with a hole in the middle. Now place this seal on the bottom of the tall tube and place the bubble of the seal on the bottom first.  This will seal the hole with the plastic nut on the bottom of the bowl.

Fig.3 Bowl fill valve

Step 4: Fig.4 shows the new plastic nut under the toilet bowl and hand tighten just enough so the bowl does not crack. You will know because the nut will get harder to turn. Next place the water fill line from the stop valve and move it to the bowl. This one is just tightened with your hand.

Fig.4 Nut

Step 5: Now turn on the water stop valve, just a crack about a 1/8 turn, and check for leaks. If no leaks, turn on the water valve another 1/4 turn. Look inside the toilet bowl and make sure that the valve is working correctly. For example, make sure the valve had just enough water up to the fill line. Usually the fill line is 5/8 below the drain tube. If there are leaks, tighten the valve seal and/or the fill line seal more. When the valve or the fill line is free of water then you know the job is done. Now check the water inside the bowl, and adjust the water level if needed. If everything is fine, turn on the water valve all the way. Finally use the dry towels and pick up any water around the toilet. It's a safety issue and can prevent injury.

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