Hi,

Humming noise from water pipe whenever turned it on at any water faucets, toilts and outside faucets.
Noise disappear right away when water turned it off.

Please advise me the possible causes and ways to fix.

Your quick reply will be much appreciated.

Thanks. Mr. Park

Hello Mr.Park,
Would this be hot, cold, or both? Do you have a PRV (pressure reducing valve) installed near where the water enters your house? How about a sprinkler system? Cheers, Tom,

It can also be friction that you hear... coming from undersized pipes... or kinked pipe in your system... the kinked pipe could be your flex line between angle stop valve and your faucet.