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I replaced all of my plumbing and now I have really low water pressure, what happened?

I replaced all of the plumbing in my house with new 3/4 inch copper. It was 1/2 before. I replaced the water heater at the same time and one sink/faucet. All of the supply lines are 3/4 which are connected to faucets by 3/8 ID supply lines, and to the washing machine and tub/shower by 1/2 inch copper. All of the valves are new ball valves to include the ones at the supply lines to the faucets. Yes, I have checked and all of the valves are fully open. Now I can hardly take a shower my pressure is so low. What happened? The pressure is not just low in the shower, it is low at all fixtures.

Public Comments

  1. reduce the size of the pipe going to your shower and that should fix it. your water supply header needs to be bigger than your supply lines to individual faucets, the rest you can leave if ya want but reduce the lilne to shower
  2. Is water pressure low throughout the house (and only really noticeable in the shower)? If so, check the pressure regulator at the line into the house. If it was replaced or improperly adjusted, you'll get low pressure. Upstairs will be more noticeable, since lower pressure supply won't push the water up to the 2nd (or higher) floors as well as feeding the bottom floor. Get a pressure gauge and figure out adapters to attach to the various faucets. Pressure should be at least 40 PSI, though I've seen many set at 60PSI or more. Check your local codes. Did your plumber install any flow restricters? Or check valves that may include a restricter. Also make sure that the street valve is turned fully on. If it's not completely open, you'll get noticeably reduced flow. Good luck! Additionally - If there is a gate valve still in the system that is used for shut off, it could be faulty. They tend to corrode internally over time and, when closed, the corroded screw gives way and doesn't allow the valve to open fully. It won;t leak externally, and the handle my bind against the corrosion making it seem as if it opened to the stop, but actuall stops partially open. I had this happen to me twice and it was a really frustrating item to find the first time (second time was easy!).
  3. I just did exactly what you did to my home. We went from 1/2 inch steel that was about 50 years old to new 3/4 inch copper. My water pressure is awesome. It's weird this is happening. You should be blown away by the new pressure. It also sounds like you did the work by yourself. The larger pipes should by the laws of physics move a larger volume of water at that same pressure from the water company. Some questions to consider and I am assuming you did the work by yourself. 1. Did you leave any debris (ie plumbers bread) or anything else in the pipes? block. 2. Were any regulators installed? Limited pressure. 3. Was ALL of the plumbing replaced? Meaning no runs of old pipe anywhere in the house. Maybe an old valve partially shut or loose sediment in a main line feeding the fixtures. 4. Does the new pipe go all the way to the water meter? Could be a loose mineral deposit in there. 5. Is the water main valve open fully? An old plumbers trick may help also. Take the screens off every tap and rinse before replacing. Sediment sometimes gets caught there and blocks flow. This is common in the spring after cold pipes start to reach warmer temperatures (expansion and contraction causes mineral build up to break loose). I don't think it'll fix it totally as all your taps have low pressure. Like I said it's weird. If you've replaced everything to new, bigger, copper lines all the way out to the water meter with no regulators or any old valves it's probably something small causing this. Something left in the main by the installer or main valve not fully on is my guess.
  4. Remove the airaters and clean the gunk out of them, the shower head too. You probably just plugged up all the screens.