Rapid 'tapping' noise in pipes. Soundfile available
My tenants have noticed rapid tapping noises in our townhome's pipes. These happen randomly, sometimes about 45 minutes or so after last water use. The tapping noise lasts about 10-30 seconds, and the frequency has been going up over the last 4 weeks. It started as once per day, and is now at 5-6 times per day. The noise stops if any water is turned on.
The noise started after my tenants tried to bleed out the outside tap after closing the hose-bibs, to winterize these pipes. Now, even though they have turned these hose-bibs back on, the tapping still continues. The tapping is in the main house pipes.
A five second long sound file is available. I couldn't figure out how to attach it, but will be happy to send it to any kind soul that wants it.