If you suspect a running toilet you can conduct a simple dye test to determine if your toilet(s) are actually leaking.
Quite often toilets leak a small amount of water from the tank or reservoir to the bowl. A small leak like this can go undetected for a long time and eventually lead to a septic system failure.
The dye test is simple. Add at least five drops of food coloring, red or blue are good choices, into the flush tank before you go to bed. If the dye is in the bowl in the morning, the flush flapper is leaking and is need of repair or replacement. If a leak is detected make the repair promptly.
Follow these steps to make the repair.
Step 1: First check the guide rod or chain on the tank stopper. If the rod is bent or the chain links are twisted, just straighten them.
Step2: Next check the float mechanism. If lifting the ball up stops the water from running, try to bend the float are down to get the right buoyancy. If you notice that the ball has water in it, it needs to be replaced. Replace is by unscrewing it from the arm and putting a new one in its place.
Step 3: If the toilet is still running, the valve seat and stopper may have corrosion or build-up preventing the stopper from closing. Lift the stopper up and check for any obstructions. Gently scour the seat and the rim. If there is a great deal of damage, replace the stopper and valve seat.
Step 4: The flush valve assembly may have to be replaced if the toilet is still running. Turn the water supply to the toilet off. Remove the assembly and valve. Take the old parts with you when purchasing new inside gaskets and assemble to endure a perfect fit. If the shaft of the assembly is cracked, the whole shaft and assembly will need to be replaced. Again, take all the parts with you to get a perfect match.
If plumbing repairs, no matter how small, are not your idea of fun, call your plumber and have it repaired right a way before you forget about it.
Remember, a leaking or running toilet can cause a septic system failure.