We moved into our house about a year ago and any time our sprinklers are running and sometimes when drawing a bath there is a noise like this from the pipes in the wall by our main valve. It's sort of a rhythmic chugging noise and is loud enough to wake me up. It's not completely consistent. Sometimes the chugging is faster or slower. I have been in the attic and the crawl space and it's definitely loudest inside the house. Also sometimes when the sprinkler valves change over there can be a banging sound but it doesn't happen every time either. Water pressure is 50 psi. I have already tried turning off the main and letting all the water drain from the house but that didn't help. The home has an old part built in the 20s and a newer section from 2005 or so. A lot of work was done on the plumbing for the renovation but I don't know if it was completely replaced. One thing that particularly perplexes me is I don't think any water is actually flowing through the home when the sprinklers are on. The main pipe comes up from the ground, goes past a shut off valve and then splits with one pipe going into the house and the other, past another shut off valve, to the sprinklers. So when the sprinklers are on I would think the water would be coming up from the ground and over to the sprinklers with the house not being involved at all. Any ideas? Ideally any ideas that don't involve ripping open the wall? The wall where the noise is coming from has tile on one side and cabinetry and a sink on the other side. Is this just annoying and I should live with it or is it dangerous? Are my pipes going to explode inside my wall? All help appreciated. Thanks.