Need help! Constant Vibrating pipes!

Hello,

I'm hoping someone here can offer some advice. I moved in to a bi-level home approx. 30 yrs old. No basement and the cold water comes straight up from the slab. Since I moved in the pipes in the ulitily room have been vibrating constantly. No matter what time of day or what I do, they continue to vibrate. It sounds like water is moving around in there but no leaks anywhere. The little triangle on the water meter does not budge at all when everything is off. It seems to start around the water meter and move up and get weaker as you go further up the pipe. However, one bathroom is directly above the utility room and you can hear it at night when all is quiet. It is more obvious in the bathroom next to the utility room where you can feel the vibration in the faucet. It is only affecting the cold water side. I've tried turning off all electricity to my house to rule out any appliances causing the issue but no difference. Opening a tap or flushing a toilet makes no difference either. I got a water pressure gauge and tested at my front and back outside faucets and both registered around 35 psi. Water pressure at the inside sinks and shower seem fine. I had a plumber out and he put a water hammer arrestor on but it made no difference. I'm not convinced the plumber knew if it would work or not. The only water to stop the vibration is to shut off the main water before the meter. Does anyone know what is going on here!? Pics of my set up are attached if of any help.
Thanks!

Sounds to me like a toilet fill valve is fluttering causing water hammer. However that would require that it be letting in small amounts of water which you could see on the water meters "little triangle".

It's odd you are getting vibrating when you have no water running anywhere in the house. Maybe it's a city main issue. Have you talked to any of your neighbours?

Hmm I checked the toilets and they seem ok. I do hear a noise from my hot water heater that sounds like a pebble stuck inside. I'm assuming this is caused sediment on the bottom of the tank. The vibrating is not as strong coming from the tank so I don't think it is related. I haven't checked with the neighbors yet but that is probably a good next step.

Are you near a water pumping station? The city may have a pump needing maintenance. My guess is no, otherwise your water pressure would be higher. Do you have a pressure reduction valve?

I've seen pressure reducing valves do that.

Hmm, pretty sure I dont have a PRV. Line just comes up and goes right to the water meter. Nothing else attached to the line.