MODERATOR COMMENT: yearofglad is asking a question in the “General Questions” forum about testing an old sprinkler system. Here’s a link: Old Sprinkler System - Factual Questions - Straight Dope Message Board
It’s ambiguous whether this is the better forum, but people might look here who could provide insights. So, I’m putting this post in Barn House forum to “advertise” the thread in GQ. Please don’t post here, go to the GQ thread.