Toilet Tank Doesn't Fill Enough

Repairs to the inner workings of a toilet tank are easier than they may appear.

If a toilet tank doesn't fill correctly, the toilet won't flush the way it was designed to do. Troubleshooting and fixing the cause of the problem is not very difficult, but the approach differs depending on whether the fill system is a pressure-sensitive valve or a float with a ball cock fill tube.

Things You'll Need

• New float (optional)
• Screwdriver
• Pair of wrenches
• Pressure-sensitive valve (optional)
• Float (optional)
• Ball cock fill tube (optional)

Instructions

1. Decide which type of tank fill system your unit has. A pressure-sensitive valve is a simple, round valve that sticks up about 1/2 inch from the bottom of the tank at the cold water in-feed pipe.

   A float is a large, oval-shaped object extending from a fill tower across the span of the tank. It rides on top of or just below the surface of the water. The fill tower is called a ball cock mechanism in this type of set-up.

2. Adjust a pressure-sensitive valve to allow more water into the tank before the valve shuts off. On top of the valve is a dial that can be turned clockwise to increase the amount of water in the tank. Reach into the water and turn the dial. Just move it about 1/2 turn and see to what level the water rises. Adjust the dial until the water level matches the scribed indicator mark on the inside of the tank.

3. Check the float on a ball cock system. Look for corrosion and holes that may be causing the float to fill with water which will, in turn, make the float ride lower and cut off the fill valve sooner than necessary. If this is happening, replace the float. Unscrew the old float and screw on a replacement.

4. Adjust the length of the float arm. If the arm is too long, the float will tend to keep the water level lower. Loosen the set screw that holds the float to the fill valve. Move the arm in toward the valve and tighten the screw.

5. Replace the ball cock valve with a new one or with a pressure-sensitive valve if the tank still does not fill to the correct level. Shut off the water supply to the toilet by turning the shutoff located just below the tank. Use a pair of pliers to loosen the nut under the tank that holds the fill valve.

   The pressure-sensitive valve installs in the same place. Don't forget to attach the thin, black overflow tube and route it to the overflow pipe inside the tank. Tighten the nut so it is snug, but don't over tighten. Too much could crack the tank. Turn the water back on and check for leaks.

   The ball cock fill tower replaces the one you just removed. Put in the new one, tighten the nut, being careful not to over-tighten, and connect the overflow tube. Connect the float to the fill valve. Turn on the water and check for leaks.

References

• Creative Homeowner: Flush Tank Problems - When the Tank Won't Fill
• The Family Handyman: Replace Toilet Valves: Flappers, Fill Valves and Flush Valves
• Extreme How-To: Troubleshooting Toilets