Is this a condition that has changed recently or was it always like this? Do you know what type of pipe was used for the line from the city main to the house?

Thanks for the reply! We moved into the house in Dec. 2002 and it has always been like this. It's either 3/4 or 1" and I assume it's galvanized steel.

I'll contact the City tomorrow but I believe it's around 80 psi.

klem1, what does this have to do with this thread?

Let's clear up some terminology:

Static pressure: The pressure of your water when there's no water use - measured in pounds per square inch (psi)

Flow rate: The amount of water that will flow through a pipe/faucet - measured in gallons per minute (gpm).

Pressure drop: The loss of water pressure on the demand side of a restriction while water is being used.

What you are describing sounds like a restriction somewhere in the water supply causing excessive pressure drop - but is often misstated as "low water pressure".

The way you diagnose this issue is to first measure the static water pressure at your home. Get a gauge that screws onto a hose bib and measure it - with nothing else (toilets, dishwasher, etc.) operating. This will confirm that you have reasonable water pressure supplied to the home. It needs to be between 30 and 80 psi. Don't guess, measure it. It also gives you some information about a PRV - if you have one.

Then get a 5 gal bucket and time how long it takes to fill it from your tub spout with both hot and cold open. You should be seeing at least 3 gpm, and 4-5 is more normal.

Assuming static pressure is fine and the water flow is low, start going backwards to look for the restriction. Begin by looking at what faucets are having the problem - and if any aren't. If your hose bibs outside are fine, for example, it could be your water softener that's clogged. Try bypassing it temporarily. That was the issue with a recent poster with similar problem.

Pressure reducing valves (PRV) reduce static pressure from the street to something less than 80 psi. They are required if the static pressure being delivered to the home is too high. If your neighbors have them, you probably do also. They usually include a screen to protect the valve from crud in the line - and that often gets clogged. It's a common issue.

Also, if you have any in-line whole house water filters, those will clog very quickly. If you aren't finding the problem, call in a plumber. I've seen valves clogged up, for example. Galvanized service lines will clog, but i've seen them work for a very long time (100 years) so that would not be my first assumption.

Thanks @stax, but I gave the OP solid information on how to think about the problem, how to test, what was common sources of the problem - It wasn't just "call a plumber".

But ultimately there are limits on what the average homeowner can do if those don't work.

Thanks for the information, Jake The Wonderdog!

The front bib's static pressure is 65 psi. The main shut-off valve is in the master bathroom located in the NE corner of the house and the hot water heater in located dead center of the house. I had a plumber come out 4 years ago to install a new water heater (we don't have a water softener unit) and he couldn't find the PRV within the house or next to the water meter, which is located at the SE corner of our front yard near the street. His best guess is that if we do have one, it's probably buried somewhere between the water meter and the house. I see the biggest drop in pressure/water flow when the washer tub is being filled with water, which evenly effects the whole house; the washer is located in the NW corner of the house. I couldn't say one way or another if we have any in-line filters. I'll have to get a 5-gal. bucket and see what the gpm is for both bathtubs.

I think you have a PRV unless your neighbor who has one is at the bottom of a very big hill from you. 65 psi is very good static pressure.

Sounds like we can rule out water softener and proably water filter.

A water filter would look something like this:

I don't see that we have one of those. We live on a cul-de-sac on the backend of our subdivision which slopes downward. Our next door neighbor to the east has his PRV in his garage, I've seen it. I'll have to ask my neighbor to the west if he has a PRV.

Thanks for checking.

Were you able fill a 5 gal bucket and determine your flow rate?

Just FYI, a typical PRV looks like the thing below:

I haven't yet, when I do, I'll post the results. Yep, that's what my east neighbor has.

Hi, Out of my league here, but I would check the shut off valve at water meter and any other valves on the main that supply water to the house Make sure they are fully open.

Good Luck Woodbutcher

Hi @Guess Who

Did you ever resolve this issue?

Not yet, but will fill a 5-gal bucket today and see how long it takes to fill it. I'll post results afterwards.

RESULTS: I tested both the SE and NE tubs and both came out pretty even. I let the water run for 1 minute and marked the bucket accordingly, both measured ~7 in. deep. So, I'd say about 2.5 gpm.

Yeah, that's low. There is a restriction someplace.

You've ruled out water softener and water filter. The remaining likely culprits - in order of likelihood:

1. PRV - screen in PRV valve. You have not been able to locate but we have reason to believe it's there. (Neighbors have one, static pressure is consistent with one).

2. Main shutoff valve(s) not fully open or clogged. I've seen both. Fully close shut off valves, then fully open. The act of closing them can often dislodge crud - and fully operating them will identify a malfunctioning valve (such as a broken gate valve). Depending on your utility, this may require a street key.

3. The service line from the street to the house is restricted. This is often guessed as the culprit without any supporting evidence. Usually it's not the issue. I've seen 100 year old galv pipe that's still delivering reasonable GPM.

Thanks for the insight. I'll turn off/on the main shutoff valve, which is located in our NE bathroom and see what happens. Is this the one you're talking about?

Any and all main shutoff valves. If you have one(s) at the meter or at the street I would do those also.

But if you can't access those, start with the one's you can access.

I'm going to turn off the shutoff valve at the meter tomorrow morning and see what happens after I turn it back on.