I think there are hidden water leaks around the house. How can I test if I’m right?
I also think that only a professional can solve the problem fast. You need to find a good plumber. I had a great experience with the guys from https://plumbernewmarket247.ca/ They solved all plumbing issues in my house when I was doing a renovation, so I can recommend them with confidence.
The easiest method — and the one I most often use — is to leverage the water meter in your favor. Just find the water meter for your home or apartment, close all the faucets in the house, and then check on the meter. If the numbers are still running, then there is probably a leak.
Just make sure there is indeed nothing in the house using water at the moment, no dishwashers running, no washing machines using water.
If the meter appears to be stopped, that alone is not a definitive conclusion. The leak might be small. So, write down the number on the meter, keep not using water for about an hour, then check on it again. If the number has changed, then there is probably a leak somewhere.
There are other ways to check for leaks, of course. But this one is the most practical. And if you don’t want to go through the hassle of doing this yourself, any company that offers plumbing repairs will gladly check for leaks, as this plumbing Denver page shows.