I recently started with this issue and I am unable to narrow it down to one thing. The issue is at times we hear s sputter when turning on the facet and flush the toilet. There were a few times we actually had no pressure or water in our shower. It only lasts about 5 to 10 minutes tops and we are back to normal which could be 5,10 or 24 hours and then we may have another episode. I was hoping someone could guide direct me to any other ways I can finally find out which is the culprit so I don't go down a black hole replacing everything.