1. Understanding how a toilet works
When a toilet is flushed, the flush handle lifts the tank flapper. On older toilets this may be a rubber ball, which opens the tank outlet and allows water to flow into the toilet bowl. When the tank is nearly empty, the tank flapper falls back into place and shuts off the water flow. The float ball falls as the water level lowers opening the water supply inlet valve as the outlet is being closed.
The toilet tank is then refilled through the inlet valve filler tube. When the water level inside the tank nears the top of the overflow pipe, the float closes the inlet valve, completing the refill cycle. The toilet is now ready for the next flush.
2. How to locate the problem
Slow water leaks are the source of most toilet problems. Begin by checking underneath the toilet for signs of water with a flashlight for more illumination. If there is any water visible, the leak may be between the water supply line and the toilet tank. Check the fitting and make certain they are tight. If the leak persists, remove the water supply line and replace the washers between the shutoff valve and toilet tank. Turn off the shutoff valve before working on repairs. A small plastic bowl, or large bath towel, is handy to catch any water in the supply line.
The next area to check is the toilet tank itself. To determine if the tank flapper is leaking, add several drops of food coloring to the tank water. Wait 10 to 20 minutes and see if the toilet bowl water has turned color. If so, the rubber flapper is not sealing the tank. Replace the flapper. It is easier removing the flapper first and then match the size and model at the hardware store. Manufacturers use many differing sized flappers, it is important to select the correct style flapper for the toilet tank. Remember to turn off the water supply before repairing the toilet.
If the tank flapper is not leaking, the problem may be the float ball itself. Check the adjustment on the float. The water line should be about an inch from the top of the overflow tube. If the float is out of adjustment or too high: bend the metal arm to reset the water level. Newer refill valves may have the float adjustment on the top of the valve. Look for a Phillips head screw to raise or lower the float ball.
Older floats may have cracked over time and be partially submerged causing the tank to fill higher than it should. If the tank is filling too high, water may be draining into the overflow tube and causing the toilet to fill and drain over and over again. To repair a float problem, unscrew the float and replace it.
In cases, when the inlet valve becomes covered with lime scale, it may be easier to replace the valve. Most valves can be dissembled and cleaned. If attempting to do this, be certain to check the diaphragm and O-rings for debris and clean as needed.
Check the flush handle and flapper lift mechanism to be certain they operate freely. There should be enough extra slack in the chain or wire to allow the flapper to close completely. The handle should operate without binding. A little Vaseline or petroleum jelly applied around the handle shaft where it inserts through the toilet tank will help it operate smoothly.
3. Avoid toilet problems with these crucial tips
To remove slime or fungal buildup in the toilet tank: add ½ to 3/4 cup of ordinary bleach into the toilet tank every 6 weeks. Pour the bleach into the tank after flushing; when the flapper drops and seals with that familiar “plunk” pour in the bleach. Swirling action from the tank refilling will mix the bleach and incoming water.
Trying to save water from each flush may actually damage the toilet. Toilets manufactured after 1994 use 1.6-gallons per flush. The modern toilet needs all 1.6-gallons to properly flush! Adding a brick or other foreign objects to reduce the capacity of the tank may create other unexpected problems. Without enough water to flush waste, a toilet is more likely to clog along the lateral drain line. Adding a brick to the tank may introduce additional sediment to the flapper and trap. If you are convinced of the need to reduce the tank capacity, a small plastic bottle filled with water is a better solution. Replace it as the plastic becomes brittle.
For water leaks in the middle of the night: close the shutoff valve to avoid further water leaks. Make the needed repair during daylight hours and when the hardware or plumbing supply store is open and repair parts are available.