Apparently this isn't water hammer since it's not occurring when I turn things off, but rather ON... Anytime I flush the toilet or turn on the shower, or any faucet, or the washing machine, it makes a vibrating/banging noise for a few seconds. This just started happening. And would love to stop it! The noise is louder if standing near the water heater so it appears to be originating close to that area. The only things we've done recently were install new shower nozzles and we did have a roofer messing with one of the plumbing vents on the roof in the kitchen (He just shook it a little to show us that it was loose). Could either of those have caused it or any ideas how we can fix this? Thank you!

Put your hand on your water meter or the inside shut off valve. Have someone run water, do you feel the vibration here even more?

Thank you for the reply. The current answer to that is no, only because it stopped doing it. It had been doing it for about 2 weeks and then one day, everything was back to normal. No more hammer noise!

Let us know if it comes back, good luck

Will do, thanks!