Illinois American Water is encouraging people to check their plumbing for leaks during National Fix-A-Leak Week. Spokeswoman Karen Cotton says some water leaks don’t drip out where you can see them. A leak inside a toilet bowl, for example, might be entirely contained inside the toilet. One thing that might help you find such a leak is turning off all the water and seeing if the meter still goes up.
Cotton says you can also put colored dye in the toilet tank. If it shows up in the bowl before you flush, there’s a leak.
The utility has more information online at this link.