I built and moved in in 1999. I live on a slab, so my plumbing is running through the walls and under the slab I assume. About 3 or 4 years ago when turning on the hot water I started to hear a humming sound in the pipes. I turned off the water and it went away. A few times since then it's happened again, and I'll go into the garage where the pipes are coming out of the wall near the water heater, and hit the pipes, and that humming sound will go away. It may even be gone for a year without doing it again. WELL, the sound is back, and this time hitting the pipes does not get rid of it. It comes and goes when I turn the water on. It's not consistent, but it's getting worse and louder. What should I do? Is it something simple that I can do or do I need to call a plummer? Do you think it's an easy fix? I'm a young girl (widowed) so I have no idea where to start, but I hate calling a plummer for something so little if I can fix it myself. Plus I live on a budget.
Thanks so much for your help!

One answer from a plumber this morning over the phone was that it could be because I have a timer on my sprinkler in the front yard so there is always water pressure waiting to be released from that hose daily... I turned that all off and it still appears to be making that sound... any thoughts?

Humming=vibration from somewhere. Shut the cold water supply valve to the water heater off. Did the humming stop? If it did the problem's in the hot water system. Listen around and feel the pipes and attempt to track it down where it's the loudest.
Now start turning stuff off and back on. Did the noise stop at any time? Back to you. Tom

I'll try those things... thanks...