I got this after reading another thread and realized I have a serious problem. I live out in the boonies so I can pretty much build/install whatever I wish. I did just that with my irrgation system. I tee'd off a 1 1/2 main, I didn't install a backflow valve or pressure reducer. I just gluded everything together and made a short run from the tee to a manifold where I put the valves. From that Manifold I made runs for 6 zones. It's not perfect but it works. Problem. I have water hammer when I shut off the shower. Looking back I think this began after I installed my system. The house is about 4 years old and the hammering didn't occur initially. What can/should I do?