Write an article based on this "Shut off the water and drain the tank. Disconnect the water supply line. Remove the original fill valve. Install the new fill valve and connect the water. Attach the fill tube. Adjust the float. Test the fill valve."
When fixing the flapper and adjusting the water level in the tank doesn't fix a running toilet, it usually means there's a problem with the fill valve. The solution for this is replacing the fill valve. To do this, you must work with an empty tank: Turn off the water to the toilet. Flush the toilet. Use a sponge to absorb remaining water from the tank. Soak the sponge, wring it out in the sink, and continue until there's no water left in the tank. On the outside of the toilet, there will be a water supply line running into the tank. To disconnect this, unscrew the locknut securing the line in place. Turn the screw counterclockwise to loosen it. You may need a pair of pliers to loosen the locknut. Once the supply line has been disconnected, you'll see a lock nut attaching the fill valve assembly to the toilet on the outside of the tank. Remove this by using an adjustable wrench to turn the lock nut to the left (counterclockwise). Once the lock nut is off, you can pull the old fill valve assembly out from the toilet tank. You may want to take the old assembly to the hardware store when you purchase the replacement. That way, you can be sure to get the right size and style fill valve for your toilet. Alternatively, you can purchase a universal fill valve. You can replace older ball float fill valves with more modern float cup style ones. Insert the new fill valve into the same place in the tank. Fit the valve into the hole in the tank where the water supply line comes in. Hook up the water supply line. Tighten the nut in a clockwise direction to tighten it. Once the locknut has been hand tightened, use the pliers to turn the nut another quarter turn. Connect the fill tube to the water output nozzle at the top of the fill valve. Position the fill tube so it's draining into the overflow tube. If there's a clip on the overflow tube, attach the fill tube to the clip to keep it in place. Check the manufacturer's directions to determine the correct float height for the fill valve you purchased. Use a measuring tape to measure from the bottom of the tank, and adjust the fill valve to the right height by turning the adjustment screw. Turn the water back on and let the toilet tank fill with water. Check the water level, make sure the fill tube isn't in the water, and listen that there isn't any water running. Adjust the float height if necessary. Test the toilet by flushing it and letting it fill up again. Once the toilet has been fixed and is no longer running, carefully place the tank lid back on.