Newbie to forum. I am tracking a low water flow to two cold water lines feeding two side-by-side restrooms. Lines run in utility room just other side of wall. This 1" copper line is on the third floor coming from a dungeon in a 50-ish historical commercial building. First thought was flow meter, replaced with a 1.6 gal same as I took out. However I was always in doubt due too why both toilets have the same problem at once. No Change. Replaced with a 3.2 gal flow meter, very little to no change. Thought maybe clogged line--great. Snaked and checked all drain lines. If they weren't free, they are now. When tracing the line I found a bladder coming off the line. Climbing on a steam heater blower unity (Operational in winter) I tested the pressure, zero, found a pressure gauge in line prior to the fixtures and bladder, it read 60-psi. Tried putting pressure in the bladder, would not take pressure. Oh yeh climbing through blower unit to get to the pressure gauge as it was installed pointed towards the wall-- X??//\\whydothat. Ok when flushing toilets and running cold water sinks in both bathrooms water trickles no not much, I asked a pretty large heating contractor friend, he said the bladder was probably old and not in use and was when they used the old well. However, when they used the well it was galvanized line, this is copper. This bladder is just above the line suppling the fixtures. I read that you can use a bladder where you have a feed line that is too small or travels a long distance causing large pressure drops. Cold this be it. Lines above this do not seem to have this problem but could not explore all cold lines. Retired city water guy said do not rule out build up in line. But lines going in other direction do not seem to be effected. Ok what's the next step. Taking the line apart to check flow? Replacing the bladder tank. We need the toilets to flush properly--maybe a tank wall toilet that would be better water savings? Call a plumber? I am a pretty good lic Handing Man and would like figuring this one out. I do a lot of work for the owner, I now know this buildings digestive system, I just cant figure out this hick-up. FBXFixIt