Why would my water in my kitchen pretty much stop when someone flushes the toilet or uses the bathroom sink or starts the washing machine?

Question

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?

Answer 1

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.

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.

Answer 2

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.