How to fix a fill valve in a toilet?

The key to fixing a toilet tank fill valve is to first identify the type of fault (no water inflow, continuous water inflow, or leakage), then inspect and repair core components such as the filter screen, float ball, and sealing ring accordingly. No professional tools are needed for the entire process. Below is an easy-to-follow step-by-step guide covering most common issues:

1. First Make 3 Preparations (Avoid Leakage/Damage)

1. Shut off water and empty the tank: Turn off the water supply stop valve under the toilet (turn clockwise to the end), press the flush button to drain all water from the tank, and soak up any residual water with a towel.

2. Gather tools: Adjustable wrench/pliers, Phillips/flathead screwdriver, old towels/bucket, white vinegar (for descaling), and spare sealing rings (universal types are available at hardware stores).

3. Use proper force: The tank and fill valve are mostly made of plastic. Do not over-tighten nuts to prevent stripped threads or cracking.

2. Repair by Fault Type (3 Most Common Issues)

🔧 Fault 1: No Water Inflow into the Tank at All

This is most likely caused by a clogged filter screen or a float ball that is too low.

1. Remove the filter screen: Unscrew the filter cover at the bottom of the fill valve (twist gently with pliers), take out the internal nylon filter screen. If it is clogged with sediment or limescale, rinse it with clean water; for heavy limescale, soak it in white vinegar for 10 minutes before scrubbing, then reinstall it.

2. Adjust the float ball:

• Ball float type: Pull the clip on the float ball arm upward (the higher the float ball, the later the fill valve closes);

• Float cup type: Rotate the screw on top of the float cup clockwise to raise it, ensuring the float cup can move up and down freely.

3. Test: Open the stop valve. If there is still no water inflow, the internal piston of the fill valve is damaged and needs to be replaced directly.

🔧 Fault 2: Water Keeps Running After the Tank is Full (Water Drains Through the Overflow Pipe)

This is either due to a stuck/deformed float ball or an aging sealing ring.

1. Inspect the float ball:

• If the float ball is cracked and filled with water (sinks): Unscrew the screw on the arm and replace it with a float ball of the same model;

• If the float ball is stuck: Straighten the arm to avoid interference with the tank inner wall/fittings, ensuring the float ball can rise and fall with the water level.

2. Replace the sealing ring: Unscrew the valve cover on top of the fill valve, take out the internal black rubber sealing ring (O-ring/flat gasket), and replace it with a new one (buy a "fill valve sealing ring kit" at a hardware store). Ensure it fits tightly without gaps when reinstalling.

3. Adjust the overflow pipe: If the overflow pipe is too low, loosen the nut at the bottom, raise the pipe by 2-3cm (so the top is higher than the float ball's maximum position), then retighten the nut.

4. Test: If water still runs continuously, the fill valve body is worn and should be replaced directly.

🔧 Fault 3: Leakage at the Fill Valve Connection (Water Seeps from Tank/Hose Interfaces)

This is mostly due to loose nuts or aging gaskets.

1. First tighten the nuts:

• Leakage at tank connection: Gently tighten the fixing nut at the bottom of the fill valve with a wrench (clockwise, moderate force);

• Leakage at hose connection: Tighten the hexagonal nuts at both ends of the hose (connecting the fill valve and stop valve respectively).

2. Replace the gasket: If leakage persists after tightening, remove the fill valve and check the round rubber gasket on the inside of the tank. Replace it with a new one if it is aged or deformed (if no spare is available, cut a rubber sheet of the same size), then reinstall and tighten the nut.

3. Inspect the hose: If the hose is cracked or the interface is aging, replace it directly with a steel wire-braided pressure-resistant hose (same length as the original), connect both ends and tighten the nuts.

3. Replace the Fill Valve Directly (When the Old Valve Cannot Be Repaired)

If the fill valve is over 5 years old or still malfunctions after repair, replacing it with a new one is more convenient:

1. Remove the old valve: Unscrew the fixing nut on the outside of the tank and take out the old valve from the inside (unfasten the overflow pipe clip first if there is one);

2. Install the new valve: Place the sealing gasket of the new valve at the water inlet inside the tank, insert the new valve, and tighten the nut on the outside (do not over-tighten to prevent tank cracking);

3. Connect the hose: Attach one end to the new valve and the other to the stop valve, then tighten the nut;

4. Debug: Open the stop valve, check for no leakage, then adjust the float ball height (when the tank is full, the water level should be 1-2cm below the top of the overflow pipe).

4. Key Reminders

Following this process can resolve over 90% of fill valve issues by yourself, with low cost and time savings.