Severe pressure drop when using shower / faucets

[jd4020]

Homeowner / DIYer here. I've been in this home for 20 years, and have battled this issue with severe pressure drop when using showers / faucets. Rural setting, house is 600' from the main, with an elevation rise of 100'. 5/8 water meter that water company says is rated at 11 GPM. 1 1/2" pvc from the main to the house, reduced to 3/4 copper where it enters the house. Pressure guage in the line where it enters the house. Pressure at the house builds to 80 PSI. When shower or faucet is used, pressure drops to 20 psi. It's usable like this, but not very well. Only one shower at a time, sprinkler or pressure washer is unusable.

Water company came out, had me turn on all of my faucets & spickets, and read the meter and it pushed through 11 gpm, so they said it was fine.

I've had multiple plumbers out to look a this, and they all say it shouldn't do that, but none have a good answer to why or how to fix it. Would a larger water meter help? I'm thinking that it's trying to push a lot of water uphill (1 1/2" pipe), and wonder if the larger pipe is part of the problem. I struggle with the concept of a 5/8 or 3/4 meter into a 1 1/2" pipe.

Looking for some guidance from those who understand flow vs volume vs pressure over an elevation rise of 100'.

 

[Breplum]

the larger pipe is to reduce friction, and that is a good thing.
the normal thing we think of when we see such pressure drop is that there is a severe restriction somewhere resulting in your big drop.
There are booster pump with pressure tank options that we've used where delivered pressure from the utility was 40 psi.
Ultimately it is an option.

 

[Sponsor]

 

[wwhitney]

Rural setting, house is 600' from the main, with an elevation rise of 100'. . . . Pressure guage in the line where it enters the house. Pressure at the house builds to 80 PSI. When shower or faucet is used, pressure drops to 20 psi.

100 ft of head is 43.3 psi. So if your static pressure is 80 PSI at the house, it will be 123 psi at the meter.

2 gpm through 600' of plastic pipe with an inner diameter of 1.5" should have a pressure drop of only 0.1 psi. http://irrigation.wsu.edu/Content/Calculators/General/Pipeline-Pressure-Loss.php

So you clearly have some obstruction upstream of the pressure gauge. I'm not sure what sort of obstruction would cause 60 psi of pressure drop with 1.5 to 2.5 gpm but still permit you to flow 11 gpm when more fixtures are open. But something is wrong with the water lateral between the meter and the pressure gauge. (*)

I'm not sure of the best way for you to proceed. You could disassemble/inspect/reassemble the connections at both ends of the lateral (with the water shut off at the meter) to check the easy to access places. Otherwise you'd have to figure out a way to inspect the rest of the 600' lateral to find a place where the pipe has been crushed or something like that. If there's debris internal to the pipe, that would require an internal inspection, not sure how you could do that.

Cheers, Wayne

(*) If the water main where your water lateral connects serves only you, it is also conceivable that the obstruction is upstream of the meter, but not very likely. Installing a pressure gauge at the meter end of the lateral and checking how that pressure changes when you flow ~2 gpm would let you rule that out. That pressure gauge should basically be unchanged with 2 gpm of low.

 

[jd4020]

I'll probably get flamed for this, but I'm looking for help here. At the bottom of my hill, where the meter is, my 1 1/2 pvc cracked at the 45. I replaced it with the setup below with copper, figuring it would be stronger. This is just off the meter, so my thought was, it's a 1" copper pipe, which is larger than what the water meter is, so I didn't think it would be an issue. Would this be enough of a restriction? I also had a break at the 300' mark at one time, and I can't remember if I used a similar setup for it, but think maybe I did.

 

[Fitter30]

100' rise 43.29 lbs drop
What pressure is before the meter? And pipe size before the meter? Have any brand or numbers off meter?
Easily have 50-60 drop
Booster pump is needed.
Wouldn't doubt at that 45° will break again because there isn't a or more expansion joints.

 

[wwhitney]

Booster pump is needed.

With 80 psi static at the house, there should be no need for a booster pump as long as the water main and lateral are appropriately sized. 1-1/2" for 600' appears to be an appropriate size for the lateral.

Cheers, Wayne

 

[wwhitney]

Would this be enough of a restriction?

A couple feet of 1" copper and a 45 degree elbow would not be enough of a restriction to explain what you are seeing.

Now if debris got into the pipe when the break and repair happened, that's another story. The change in inner diameter would provide a place for a pebble or other debris that is larger than 1" but smaller than 1-1/2" to get caught and act as a flow restrictor.

Cheers, Wayne

 

[Fitter30]

We have no idea if full port valves were used, piping in the house or what it is before the meter.