I've lived in my house for about 3 years. It was originally built in 1970. When we had it inspected before buying 3 years ago, the inspector said the water pressure was 60 PSI. The few water pipes that are visible (they're mostly in walls and below slab) are copper.
The whole time we've lived at the house, I've noticed a repetitive banging/knocking sound in the walls of our basement bathroom whenever water was running in the house. Not terribly loud, but consistently there. The frequency of the knocks could be one every few seconds if one of the exterior hoses is turned on very low all the way up to 5-10 per second if water usage is high (washing machine filling up, sprinklers running, etc.).
This is separate from what I'm reading online about "water hammering," which as I understand it is knocking that happens specifically when a valve gets turned off. I think I have heard that happening in my pipes as well, but I honestly haven't paid attention since I've been more worried about the repetitive knocking when water is flowing.
What could be causing this? Should I be concerned? Should I fix it?
I'm asking now instead of 3 years ago because I'm considering having my water main partially dug up to install a water main turnoff valve (there's no clear place indoors where the water main pipe is, so installing a valve outdoors is the safer way to go vs. knocking out walls randomly), and figured that might be a good time to install water pressure mitigation equipment too if need me.