If your toilet runs continuously, fills slowly, or shuts off at the wrong water level, the fill valve may simply need adjustment. This valve controls the amount of water that enters the tank after each flush and determines the final water level in the tank.
In many cases, a small adjustment to the float or adjustment screw can get it working right again without replacing any parts.
Quick Answer
To adjust a toilet fill valve, locate the adjustment screw or float mechanism on the fill valve inside the tank and raise or lower the float until the water level stops about 1/2 inch below the top of the overflow tube.
How a Toilet Fill Valve Works
The fill valve is the tall mechanism inside the toilet tank that refills the tank after flushing. As the water level rises, a float attached to the valve lifts and eventually shuts off the water supply.
If the float is set too high, the toilet may run continuously or refill repeatedly. If it’s set too low, the toilet may not flush properly because the tank doesn’t hold enough water.
Adjusting the float restores the correct tank water level.
Tools You May Need
Most fill valve adjustments require only basic tools:
- Screwdriver (flathead or Phillips)
- Small adjustable wrench (occasionally)
- Towel or sponge
Step-by-Step: How to Adjust the Fill Valve
Step 1: Remove the tank lid
Carefully lift off the toilet tank lid and set it aside where it won’t be damaged.
Step 2: Locate the fill valve
The fill valve is usually positioned on the left side of the tank and connected to the water supply line below the tank.
You will see:
- a vertical valve body
- a float (either a cup or ball)
- an adjustment screw or clip
Step 3: Check the current water level
The correct tank water level should be about 1 inch below the top of the overflow tube.
If the water level is higher or lower than this, adjustment is needed.
Step 4: Adjust the float
Different valves adjust in slightly different ways.
Float cup style valves (most common)
Turn the adjustment screw on top of the valve.
- Turn clockwise to raise the water level
- Turn counterclockwise to lower it
Ball float valves (older toilets)
Gently bend the float arm slightly upward or downward.
- Bend upward to raise water level
- Bend downward to lower it
Step 5: Test the adjustment
Flush the toilet and allow the tank to refill.
Watch the water level as it rises and confirm that it stops about 1 inch below the overflow tube.
If necessary, repeat the adjustment until the level is correct.
Adjust the Refill Tube
The refill tube directs water into the bowl during toilet tank refill.
Make sure the small flexible tube is clipped to the top of the overflow tube and pointing into the overflow pipe but not pushed down inside the pipe. Incorrect placement can cause bowl water level problems.
See: Toilet Bowl Water Level Too High or Too Low
When Adjustment Doesn’t Fix the Problem
If adjusting the fill valve doesn’t stop the problem, the valve may be worn or damaged.
Common signs include:
- toilet continues running
- tank fills very slowly
- valve makes squealing or humming noises
To Hire a Plumber…
If the repair turns out to be more complicated than expected, you can always find a qualified plumber near you.
For hiring advice, see Trade Secrets for Hiring the Right Plumber.
Related Articles
If you’re not sure what’s causing the problem, see our
Toilet Repair and Troubleshooting Guide for a complete diagnostic overview.
Also see:
How to Fix a Running Toilet
How to Fix a Toilet That Won’t Fill With Water
Why a Toilet Makes Noise and How to Fix It
How to Replace a Toilet Fill Valve
