One end of my house has great water pressure. This includes 2 baths downstairs. The water heater for this end is in the attic above the master bathroom. No problem there.

On the other end of the house, the water pressure is very low. That end has the kitchen, a full bath upstairs, a half bath down, a washer, and a dishwasher. The water heater for this end is upstairs adjacent to the full bath. When one is running water on this end of the house, the other faucets on this end will have only a slow, small stream. This is true of both hot and cold water. (This does not impact the good pressure end of the house.) When water is running in the kitchen end (low pressure) there is an audible noise like water flowing in the attic near the water heater that feeds the good end (normal pressure) of the house. I thought it had to do with that water heater since it sounds like it is actually in the water heater. I had a plumber check it out. He thought something was stuck in the water heater pipes. He replaced all the piping on top of both water heaters. No help.

I ran a garden hose from an outside faucet at the good end of the house to an outside faucet on the bad end. The hot and cold pressure became normal inside the house at the bad pressure end! What possibly causes this pressure problem, and how can it be fixed? Is it proper to add a separate line from one pipe in the good end and feed water into the bad end at some point – say into the water line at the half bath?

  • Is this affecting hot and cold or just one? If just one then probably a blockage in one of the pipes.
    – crip659
    Commented Feb 3, 2023 at 19:48
  • Both hot and cold. Commented Feb 3, 2023 at 19:49
  • Seems like a blockage(maybe too much solder at a joint). Would imagine it is in the cold water line, unless you have a hot water line running the length of the house, the second tank would be fed(pressurize) only by cold water line. The blockage will be in between the last good pressure tap and probably the second hot water tank. Replacement of that line would be fastest, or can check valves/joints for problem.
    – crip659
    Commented Feb 3, 2023 at 22:34
  • Interesting! I will get this to my plumber! Semper Fi Commented Feb 3, 2023 at 23:42
  • Check the lines to be sure all of the valves are open. If they are then it appears you have an obstruction in the cold line feeding this side of the house.
    – Gil
    Commented Feb 4, 2023 at 2:13

2 Answers 2


Your action of connecting the two water faucets proves that there is a pressure loss in the cold water pipe. As others have, said it's probably an obstruction.

Your question - Is it proper to add a separate line from one pipe in the good end. There is nothing wrong with having multiple feeds. And if the pipe diameter is low for its usage then water finds its own way through the path of least resistance and flows via the best path.


There are a ton of possibilities but a few that I would check first:

  1. Check the pressure regulator. Probably not the cause if it's just on one side of the house but worth inspecting.
  2. Check for leaks. Water leaks can cause low pressure in certain areas of your home.
  3. Check the pipes: Over time, mineral buildup, rust, or debris can accumulate in pipes, causing low water pressure. You might just have one bad pipe in the middle of the house where flow thru is poor.

And the really obvious one is make sure that water isn't on somewhere else in the house.

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