I hear dripping behind the toilet and shower wall upstairs in my bathroom and just below in my kitchen -- all the time! There is no relationship to rain or running water. I turned off the water to my toilet, no change. Then, I turned off the main water valve to the whole house, STILL no change. I just had my roof repaired (unrelated to this problem) but I heard the dripping before and after the roof repair. I see no water accumulation anywhere or any sign of excessive moisture. My water bill was higher the past few months, but I had a badly leaking water heater that I just has replaced and I haven't seen the water bill since the replacement. What's up?

Does this noise happen more with cold weather? If so this could be contraction and expansion in the pipes in the walls. N read on;
Knocking, popping, creaking and crackling pipes are a common complaint, especially in colder weather. I can tell you what's happening and take the mystery out of it but you're not going to like the repair. When a draw is made on a hot water line the line expands against a pipe strap next to a stud and when you drain hot water from your tub or shower it goes into a chase that is a little cooler then room temperature. The heat expands the pipe causing it to rub against the stud to which it is pipe strapped. This is the sound you hear. As it cools it contracts and the noise is heard again. To repair it you must tear open the walls and locate the pipe strap that's causing the problem and shim it tight. Most people when they learn what causes it just elect to live with it. Good luck and thank you for rating my answer. Tom

You may have an internal crack in the toilet. It lets water leak out, drops down the stack and you hear it when it hits an elbow. Leave the toilet water off a couple of days and see if the level in the bowl drops. If it does, you need a new toilet.