This relates to the recent GPM thread. What size supply line and meter do you guys have for most residences in your areas? The majority, probably at least 90%, in our Colorado Springs area are 3/4" copper with the 5/8(3/4) meter, with pressure typically around 50-60 psi. I work on many systems with those specs that are not not designed within what we call standard, if you calculate GPM, friction loss, pipe size, blah, blah, blah, and they work fine, and have for years and years. 15 GPM on the zones will USUALLY work fine here, and still no water hammer, and with ideal throw from the heads. I would rather see 10-12 GPM, but I didn't install these. But when I was still installing, I would occasionally go around 15 to prevent having to do another zone. I know some systems that were put in with much higher GPM figured, but the pressure is a lot higher as well. A lot of our systems do have a second PRV to allow higher psi for the system than what the house uses. Sometimes adjusting the pressure higher will allow me to get the system operating better if the designed GPM is just too out of whack. So I'm just wondering what most supply and meter sizes are in your areas.