Water Runs Non Stop
The handle is stuck
If the tank handle is loose it can be tightened by using an adjustable wrench to turn the locknut on the inside of the tank counterclockwise.
If the nut cannot be turned you might try applying a lubricating oil and allow it to sit for several minutes before attempting to tighten the nut again. If that does not work you may need to remove the nut by cutting through the handle shaft with a hacksaw. You will then need to replace the handle and trip lever, which is attached. Simply remove the trip lever from the chain and slip it through the toilet tank hole before replacing it with a new handle assembly.
Tank water level is too high
Reposition the float ball
If the float ball is too high it will allow water to run into the overflow pipe. You can simply bend the float arm down slightly to keep the water about 1 inch below the top of the overflow pipe. Flush the toilet to a make sure it enough water is getting into the bowl. If the toilet does not flush completely you may need to adjust the float ball back up slightly to get more water in the tank.
If it also possible that the float ball is damaged and allowing water in. If this happens the float ball will not rise enough to close the ball cock. The float ball can be screwed off of the float arm counter clockwise. You may need to use pliers to grasp the float arm. When placing the new float ball on the arm, apply petroleum jelly or plumbers tape to the threads.
Adjust a water-intake assembly
Your toilet may have a water-intake assembly instead of a float ball. To adjust the water level in the bowl so it does not flow into the overflow pipe, pinch the clip attached to the thin metal rod and slide it and the cup down to lower the water level. Sliding the clip and cup up will raise the water level. Try moving the clip about an inch at a time.
Adjusting a metered fill valve
Your toilet may have a metered fill valve instead of a float ball or water-intake assembly. To adjust the water level, simply take a screwdriver and turn the knob counterclockwise and half a turn at a time to lower the water level. Turning the know clockwise will raise the water level.
Lift chain or wire is out of place or damaged
If the lift chain in the tank it too short it may be allowing water to seep through the flapper valve. If there is excess chain you can use pliers to open the links and reposition the chain. If the chain is too short you will need to replace it. Using a paper clip or other other wire to lengthen the chain will cause it to corrode.
If your tank assembly has a lift wire you can loosen the screw attached to the guide arm and move the guide arm up or down to adjust the length.
Ball cock is damaged
The ball cock opens and closes as the float ball falls and rises with the water level in the tank. This action controls the flow of water into the tank. With a plunger-style ball cock the float arm pushes the valve plunger and washer to stop the water flow. With a diagphragm-style ball cock the plunger pushes against a rubber diaphragm.
Before working on the ball cock turn of the water and flush the toilet to empty the bowl. Remove the screws surrounding the ball cock assembly to gain access to the washers or diaphragm. You may need to slide the float arm out of the way to gain access to the assembly.
Remove the washers or diaphragm from the valve plunger with a small screwdriver. Use vinegar and a small brush to clean sediment from inside the ball cock and washer or diaphragm. Once cleaned reassemble the parts and the ball cock. If any of the pieces appears damaged or if the water continues to run, replace the ball cock.
Flapper or flush valve needs servicing
First try cleaning minderal deposits from around the valve seat. This can keep the flapper valve from sealing properly and allow water to seap into the bowl. First turn of the water and flush the toilet to empty the bowl. You can unhook the flapper valve to get it out of the way. Using emery cloth scrub the inside of the valve seat to remove the mineral deposits. Next coat the valve seat with petroleum jelly to help the flapper valve make a tight seal. Replace the flapper valve, turn on the water and check to see if the water still leaks.
If the flapper valve is old it may be deformed. In this case you will need to replace it. You can unhook the valve and remove the lift chain from the valve. Be sure to purchase a similar size replacement valve.
If the valve seat is damaged you will need to replace the entire flush-valve assembly. You will need to remove the tank to do this. Be certain to turn off the water supply and flush the tank to drain it. You might also want to place newspaper and towels on the floor to soak up any water that may leak out. Using and adjustable wrench loosen the nuts at the supply tube and push the tube aside. Next, use a flat-head screwdriver to hold the bolts inside the tank still while using an adjustable wrench to loosen the nut on the bottom of the tank. You will then be able to lift the tank off of the bowl. Lay the tank on the newspapers or towels.
To replace the flush-valve assembly first remove the old one by unscrewing the locknut on the bottom of the tank. Use a hacksaw to cut the new overflow pipe to 1/2 ince below the tank top. Put plumber's putty on the washer at the base of the flush-valve assembly and push the assembly against the tank opening, removing any excess putty. Use a monkey wrench to tighten the locknut. Replace the gasket over the locknut and replace the tank on the bowl and reassemble them.