I've been hearing this sound for a month now. It stops when I flush the upstairs toilet for a couple minutes then it starts again. I see no water moisture but it just keeps on ticking. It also coinsides with very hot weather and keeping the air 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

It is a dripping noise inside pipe that can be heard through wall

Nothing to do with cold weather.it's been 80-90 outside

Hi Karen

It could be that the toilet tank fill valve has failed and needs to have parts cleaned or replaced. This can be confirmed by observing the OVERFLOW PIPE inside the toilet tank... if water is up and level with the top of the overflow pipe then water is probably dripping over and into the overflow pipe causing the dripping sound.

If the toilet periodically fills, or "ghost flushes", then most likely the flush valve assembly and/or the flapper has failed and needs to be replaced to stop the dripping. This can be confirmed by taking 10-20 drops of food coloring into the toilet TANK and waiting an hour or so to see if the colored water shows up in the toilet BOWL... if so, then the flush valve and/or flapper is the most likely suspect, for sure!

See image below...

Back to you

Mark

Thanks massplumber2008.great advice. My toilet innards has the big flushing ball inside. I'm off to the hardware store to see if can fix the flapper valve on my own.