If you notice the water coming on by itself to fill the tank of your toilet, the problem could be your toilet’s flapper valve. You can easily renew it or replace it yourself and save plenty of money.
Flapper valve? Most toilets have a flapper valve. The flapper valve holds the water in the tank until you press the handle to flush the toilet; doing so raises the valve and allows the water to flow from the tank into the bowl. (There are some other methods of getting the water from the tank to the bowl. There are other methods of getting water from the tank to the bowl, but the flapper-valve method has been around a long time and is probably the most common.)
Over time, the flapper valve and the seat on which it sits can be fouled with hard water sediment, rust, lime, or other dirt and grime. (Amazing how much dirt and grime is in “clean” water.) The valves can also lose their flexibility, which keeps them from sealing properly. Thus, water slowly and continuously seeps from the tank into the bowl. If you watch closely, you might see it form little ripples in the bowl. When the water level gets low enough, the toilet mechanism turns the water on to re-fill the tank, and you hear it, which lets you know it’s time to work on the flapper valve. You can verify that the flapper valve is leaking by putting a few drops of food coloring in the toilet tank and looking to see if any of it ends up in the bowl after an hour or two.
You might try cleaning the valve and valve seat. Remove the valve and clean it with a scrub brush, scouring pad, or steel wool. A bit of dishwashing detergent might help. Do the same with the valve seat. Once it’s all clean, re-assemble it and check to make sure it no longer leaks.
In my experience, once a flapper valve is leaking, it needs to be replaced. Obtain a new one from your local hardware store. Remove the old one and install the new. There are plenty of youtube videos that will show you how. You might want to save the chain and the metal clip in your hardware jar; they might come in handy for some other job. I used such a clip once to replace a lost cotter pin.
One final note: the various toilet cleaners that “clean the bowl every time you flush” are bad for the toilet mechanism in the tank. Avoid toilet cleaning products that go into the water while it is in the tank.
As usual: Do it yourself and save $$$.
Which reminds me of a story: I had a friend, a little old lady, who called a plumber when the water in her toilet kept coming on. The visit from the plumber cost her something around $100. That seems like a lot to charge for the few minutes of labor needed to replace a part that costs about $6 (retail) — but I can understand that the plumber had to take the time to go to her home and he could have been working on another job (maybe something that would better justify a plumber’s time) instead of replacing a flapper valve. Still, I wish she had told me about the problem before she called the plumber. I would have been happy to do it for free.