Hey everyone, Im trying to seek help for a problem I'm having in my residence. I believe my house has a water pump, not sure since I cant see it or find it for that matter, but it is making a weird vibration at times. In my utility room on the inside wall there is an insert for Hot and Cool water with a trap hole for my washer. Approx 2ft above that is a copper pipe that makes a U shape in my drywall. It has a shut off, and a black solenoid looking thing. It comes out from the wall, then back into the wall. Behind that pipe is where I hear water pumping when I operate any faucet in my house, and just recently, the vibration. It will vibrate after a toilet flush, and will only stop after I shut off the valve and turn it back on. I have looked everywhere in my house for an access, but Im on a slab, and there is no attic access to the spot I believe it is located. Has anyone ran into this type of pump or have experience repairing one? Is it located behind drywall and will I need to cut out drywall to access it? It is important to note it is a newer model home in a subdivision. Any help would be appreciated, thanks.