We bought a log cabin 3 years ago and have just dealt with the water problems because it is something we can live through and we're afraid it'll cost a ton to repair. It doesn't appear to be a water pressure problem because it has great pressure when you first turn it on. But the longer it runs it slows down drastically or if you're washing dishes in the kitchen (by hand; no way we could have a dishwasher with this water problem) and someone flushes the toilet or turns the washing machine on the kitchen sink water flow gets very low and you have to wait almost 5 minutes for it to come back fully to finish the dishes. Same with our washer -- if you're filling the washer for a load and someone washes their hands in the bathroom sink the washer stops filling up and just says no water detected. Or you're in the shower and someone uses the water it slows way down too, and I also think the longer the shower is on the slower or lower the water you have. We have checked for a water pressure valve and we only have one up at the main. And it's been checked and the water company has checked to make sure it's open all the way as well.

We only have one shut-off in the laundry room for the entire house and it's just a blue knob you turn.

We have city water.

It's a 1-bath home. And it doesn't matter if it's the hot or cold water being used.

Any tips or reasons why this is happening?

  • 1
    Usually want around 40 pounds of pressure for decent flow. Might get a reduced flow if two taps are running, but they should not stop. Size and age of the pipes would be good to know, old pipe might be getting gunked up and instead of 1/2 inch only be 3/8 or less(this for very old pipes).
    – crip659
    Feb 2, 2023 at 19:29
  • Do you have a filtration or hard water system?
    – JonSG
    Feb 2, 2023 at 19:53
  • your water pressure regulator is broken
    – Traveler
    Feb 2, 2023 at 20:03
  • Do you have a pressure tank anywhere in the customer side of the meter? Feb 2, 2023 at 21:30

2 Answers 2


There's some sort of restriction in the pipe - having pressure until you attempt to also have flow is fairly diagnostic.

Unclear what tests the water company performed, but if they disconnected your house pipe after the meter (or opened a hose bib after the meter) and maintained good flow when testing, the problem is in the house. If they did not do something like that, but only looked at pressure without flow and was the valve open, the problem could be outside the house.

My classic example of this problem is a pipe fitting almost, but not quite, completely blocked with solder by someone. There can be other causes, such as a partly crushed or heavily corroded pipe.

my image of nearly plugged joint

If the problem affects whatever the very first place (as the pipe runs) in the house you can draw water from is, it's between there and the supply. If it does not affect that location, it's between there and where you have the problem. Since it affects hot and cold equally, it's before the water heater cold supply splits off from the house cold supply.

  • Agreed. The reason you have great pressure at first is because you're drawing from the pressure tank. As soon as it is empty, you're on the water supply in. As you said, it takes 5 minutes to have pressure back up. That's because the pressure tank has filled back up. Sounds like you have roughly 1-3gpm coming from the house side of the restriction. You should have a faucet where the water line comes in from outside. If so, test it for pressure after you use up the water and cause the no water condition. Should have lots of pressure. If not, the restriction is outside. Otherwise, it's inside.
    – asp316
    Feb 2, 2023 at 21:19
  • A partly closed valve is also a partial blockage. As could be a pinched pipe.
    – keshlam
    Feb 2, 2023 at 23:14
  • @asp316 You mention a pressure thank, we don't know if they have a pressure tank or not, the OP mentioned they were on "city water", it would be unlikely for them to have a pressure tank other than expansion tank for the water heater. Still....I agree it's most likely a blockage somewhere. Feb 3, 2023 at 13:43

Be sure the incoming valve is fully open. If you have galvanized pipe it is probably corroded almost closed. You can test it if you are comfortable working with plumbing. First you can remove part of the incoming pipe after the valve that you have closed. Temporarily connect a large diameter garden hose to it and take it outside or over a drain or sink. have someone open the valve, if you get good flow it is on the line from there to the pressure tank. If not it is highly likely it is on the city side from the tap to that valve.

I would guess that has been a problem for a long time as normally pressure tanks are not used with "city" water as they maintain pressure. They are used with well pumps which you do not have. I expect in the not to distant future you will lose water as the line closes. When you repair if it were me it be sure to put a filter inline with the incoming with shutoff valves in front, behind, and a bypass valve.

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