Recalcitrant water closets or getting your toilet to stop running
Have you ever noticed that sometimes you flush the toilet and the toilet just keeps running and running and running? It’s not supposed to do that.
If you do what I usually do, you juggle the handle to get it to stop. This is a temporary fix. You need a long-term solution or the water will keep running with future flushes.
What should you do? The first thing to do is to take the lid of the water closet off (this is your water tank). There is a chain on the contraption in the tank. Is it slack? If so, you need to unhook the chain and then re-hook it so that the chain is not pulled so tightly. If the toilet still continues to run, that is not the problem.
You should then look at the round piece of rubber that covers the drain in the bottom of the tank. Push on it a few times, to see if it is sealing well. It may be shot and may need to be replaced.
You will probably want to empty out the tank before you remove the round rubber cover, so turn off the water next to your wall and flush the toilet. This will make the toilet empty and it won’t be able to re-fill itself.
The rubber piece comes off pretty easily, so take it off and then take it to the hardware store to get a replacement. Bringing the piece with you will ensure that you get a new one that will fit your toilet. When you get back home, replace the rubber piece by reattaching it to the toilet. Turn the water back on at the wall and the toilet will refill. Flush it again, to make sure that it will stop.
If neither of these issues is the problem, you may need to replace the entire flushing mechanism; you can either pay a plumber about $100 minimum to make a house call or you can take a picture of your toilet, bring it to the hardware store to get a new mechanism, and then (following the directions on the package) replace the mechanism yourself. This will take a couple of hours and will require a wrench, a screwdriver, and a bucket.
I hope that this helps solve your running toilet problem!