You really don't want to go above 80psi. Really high pressures within the household plumbing can cause fixture valves to prematurely fail. Pressure can be checked at a fixture far away from the PRV to make sure the PRV is properly working. By also going fixture-to-fixture, you can map pressure throughout the water supply system in the house, it may help unmask a problem.

I'd check the obvious. Pressure at a fixture. Valves are full open. That proper valves were used where needed; gate versus globe, or full-port ball valves, etc.

That the plumbing is right sized. At a minimum, it's usually 3/4" pipe from the water heater, etc, to the bathroom, then half-inch to the fixtures.

Are there a lot of bends in the plumbing? Each 90 degree turn in the plumbing adds resistance to flow.

If PEX was used, I once uncovered a kink in the tubing that was restricting flow.

Ask if water hammer arrestors were installed at the laundry box. They're not really going to affect flow, but they can ease the transition when the washer valve opens and closes.

If it's indicating everywhere, that's one thing. If it's just indicating at the shower valve, for example, then the shower valve itself can be checked. Some valves have "stops", or on/off valves, on the shower valve itself. Make sure the stops are full open. Also, valve cartridges can be pulled, and water turned on, to flush the valve of any debris. If the plumber or his assistant got overlay enthusiastic with the flux and solder, solder debris can sometimes gunk up the flow.

Good luck, I hope you find a simple resolution.

Is it just the washing machine and dishwasher that cause this? What about the sink, tub, etc?

To be clear, this is not a "pressure" issue - the static pressure is fine (80 psi).

This is a flow restriction issue that causes pressure drop as water is being used.

A new dishwasher isn't a high flow appliance (measured in gpm - gallons per minute). A modern washing machine isn't very high flow either. I would guess you are about 2-3 gallons per minute for each of them.

The solution is for your plumber to install some temporary pressure gauges so that he can determine where the pressure drop happens and where it doesn't happen.

So, for example, a pressure gauge located someplace near where the water enters the house (after the PRV) would tell you if there was an obstruction from the street. Turn on the washer and see if the pressure drops significantly.

A gauge after the water heater or water softener would likewise tell you if there was a restriction there. Again, run the washer and see if the pressure drops significantly.

At one time, my old PRV failed. I replaced it with a new one. I then noticed that even though the pressure was correct, the flow was restrictive. I then discovered that I had installed a smaller sized PRV than before ( lower flow rate). I replaced it with a larger one and problem solved.

Is it legal to install a bypass for your PRV with a lockable valve? I've seen that in commercial installations. It's a sure way to test your PRV.

Seabornman

A pressure gauge will show the problem without any risk of bypassing the valve.

MongoCT - this is so helpful. Pipe is 1 inch coming into the house and 34 inch within the house. I love the idea of checking the pressure at each fixture - wonder why the plumber didn't think of that. It makes so much sense. Is this something that if I bought a meter I could do on my own or would I need a plumber to do it? I am not sure about 90 degree turns - is this something I would see now that the house is finished? There are water hammer arrestors, the plumber checked for that. That was his first guess as to the problem. What is PEX?

Jake The Wonderdog - the washer and dishwater are just the most noticeable. If you try to run a bath and take a shower you notice the drop as well. Love the idea of the temp water gauges. I have to talk to the plumber about that. While I am frustrated he kind of hacked it up to the appliance, he is a friend of the family so I can talk with him about this.

Thank you everyone!!

PEX is a type/brand of plastic pipe. It is bendable and usually colored blue for cold and red for hot.

With 1" supply and 3/4" branches, it's really unlikely that elbows or undersizing is causing this issue. I would be really surprised if there was a kink in the PEX - something like that usually gets noticed right away - particularly in 1" PEX.

My guess is that there is crud in the PRV screen from the tap at the street. But the point here is not to guess - take actual measurements with a gauge. Just to be clear, what you are measuring is pressure drop - not static pressure at each fixture. You want to start by measuring soon after PRV. Again - the gauge should read about 80 psi when no water is running. When you run the dishwasher the pressure shouldn't drop much. If it does, you have a significant restriction upstream of the gauge.

Hi, make sure all the valves are open all the way.

Even at the meter.

Good Luck Woodbutcher

You all have been so much help in trouble shooting this. I have just been slammed and am just now trying these things. What I have found that the pressure is 60psi at the spigot outside int he front of the house which is right after the PRV so the first place that the water goes. But when I turn on the washing machine that pressure drops to 20psi. So logically to mee the issue is either the PRV or before the PRV. Does that make sense or am thinking about it wrong? The PRV has been changed. I am guessing the only way to test the water before the PRV is to get a plumber out - is that right?

Basically I am thinking something is wrong with the meter or between the meter and the PRV.

A shutoff valve at the meter is not fully on?

L'Anda Johnson

You are correct, there is something wrong from the street up to and including the PRV.

So let's talk about odds - places to look:

The most likely places for a restriction is someplace the pipe narrows down already. Those places would be:

1. The shutoff valve at the street

2. the shutoff valve before the PRV

3. The PRV

Clearly you want to be sure that the valves are all the way open as Weedmeister suggested. You may want to close the valves you have access to and re-open them (again, only the valves upstream of where you measured your pressure). Sometimes if there's significant crud blocking the valve you will feel it as you close the valve. Closing the valve can sometimes break that up and cause the crud to flush through when you open it up.

I know you want to rule out the PRV because you replaced it... but if the valves are open THE most likely place for this problem is at the PRV. More specifically, there is a screen on the PRV inlet that can get clogged from debris because this is a new line. Be sure to rule out the screen on the PRV - simply because that's the most likely source of the problem.

You said that this was new construction. Was the water service line new (new development) or was there a house there previously and you re-used the water service line from the street?

This is what a PRV screen looks like:

How did this get resolved?

There is no resolution yet. The Palm we came out and added a spigot right after the meter and the pressure there is 50-60 and drops when the water is being used to as low as 20 so it looks like it has to do something with how the water is coming to the house from the city. The plumber said that at the meter the pressure should be closer to 150 psi. The city is saying it is fine. Either way I think it probably shouldn’t fluctuate like that. Not sure what the issue is but I have a fight with the city.

Hi, Sorry you're having so much trouble. Maybe no one adjusted the PRV. I have some directions from an installation. Measure the distance one the bolt on the bell housing so you can put it back if needed. Screw the bolt clockwise into the bell housing to raise the pressure and counter clockwise to lower the pressure. Maybe?

Good Luck Woodbutcher

@ L'Anda Johnson

I'm sorry that responsibility for this is being passed around.

I'm assuming that "spigot right after the water meter" means before the PRV.

This means there is a restriction before this.

Static pressure isn't the issue. A static pressure of 50-60 psi is fine. The issue is how many gallons per minute you are able to get from your water service. The indicator here is that pressure drops to 20 when you use 4 gpm.

Your plumber should understand this - and if he doesn't then you should get a different plumber. As long as the plumber is talking static pressure to the water company, they are going to reply it's not a problem. When you say to the water company - "there is a restriction and we are only getting x gpm right after the meter" then they will understand.

What's not clear to me is where the division in responsibility is - Water company / Homeowner. This is different for each utility. For some, it's at the meter. For others it's at the property line or the street. Again, your plumber should know this and know how to work with the utility to get this resolved.

Wow, the city is doing that for you? In my city, the homeowner is responsible for that line.

Yes. Meter to the house is homeowner. Meter to the water main is the city.

Not in this jurisdiction (MD). Street Shutoff to the house is county.