Noise from water running through lines in walls

I bought a house last year and it has a main bath that is adjacent to a living room. Whenever the water runs in the bath it is very loud in the living room - right on the other side of the wall. Doesn't matter if it is sink, toilet or shower. It is loud. What options do I have to quiet the noise? I don't think it is vibration from the main or anything like that, just water flowing through faucets and valves.

In my last house I built it myself and insulated the walls around the bathrooms. Twofold, one to keep water noise down and two, to keep human noise from escaping. The walls around the bath also help enclose the master bedroom with insulation noise barrier.

I am not opposed to removing drywall and filling the cavity with insulation. Is there a best kind? I just used a plastic enclosed fiberglass batt in the old house. But have thought maybe spray foaming the pipes would be easier here. Though it would be a beeeeaaaatch to work on later if needed.

Any ideas?

I would drill small holes and fill the wall cavity with expanding foam. Don't over do it though or I think the drywall may bow or break. I'd start with maybe half a can at the wall mid point above the water supply valves. Don't drill too deeply and risk damaging the lines. I believe this rigid foam will minimize sound and vibration. Some foam will expand back through the drilled hole so just shave that off and top with patch compound. I know someone who insulated a complete old house this way!

Thanks Don, I think that would be easiest, but like most everything else in this house, I have had to repair stuff. The foam would make it much harder to repair the shower/tub valves. But would be the quietest.

You might get a look inside the wall with a small scope. I know these are available online to interface with a cell phone or Harbor Freight has a fairly cheap self-contained unit. As you indicate, it would be important not to seal off valves or pipe connections. Most of the noise reduction benefit will be at mid points of the pipe, in my opinion anyway. You could cut some small openings above the valves and then insert soft insulation or crunched up newspaper balls or other packing material. This would keep the messy foam out of the valve areas.

If the noise is louder at the wall mid point, cutting a horizontal slot in the stud bay would allow the placement of a 2x4 fire block, slotted to receive the vertical pipes. Then, maybe fiber glass the pipes into the 2x4 or pack the slots with rubber insulator or strap the pipes with metal strapping or zip ties. This idea is more trouble than the rigid foam though.