Plumbers: Water Pressure Question

November 06, 2023, 12:54 PM

chbibc

Many factors to consider:

1. Size of your water service to the house and what pressure is in the public (street) water main.

2. With a 50 foot elevation difference you will lose 21.64 psi. That's just elevation and not friction loss through the 700 feet of service.

3. Where's the meter? In a pit down near the property line or in your house? Regardless, you'll probably lose another 2 psi through the meter and valving.

4. Someone mentioned a pressure regulator. You may or may not have one.

5. Age and composition of the water service may be a factor.

6. Booster pump may be a solution, but adequate water has to be there on the inlet. The pump cannot create water, only a pressure boost. I.e. if you need 6 gpm, that amount at a positive pressure needs to be available at the pump inlet. (NPSH - net positive suction head, or, if the pump is not getting water Not Pumping So Hot). If your water service is too small, has diminished inside dimension (think clogged artery), has a valve partially closed or obstructed, etc. these will contribute to flow and pressure drop.

7. Other factors that contribute to pressure loss are backflow preventers, which you may or may not have on your service.

Have you always had low pressure or is this a recent development? Do you know the water pressure in the house and at the street? Your water purveyor should be able to provide you with flow test results from a nearby fire hydant that would indicate pressures/flows in the street main.

November 06, 2023, 01:25 PM

Rolan_Kraps

chbibc,
Thanks for the detailed reply. My answers are below:

quote:
Originally posted by chbibc:
Many factors to consider:

1. Size of your water service to the house and what pressure is in the public (street) water main. I believe it is 1 1/2" steel pipe. Does that sound right?

2. With a 50 foot elevation difference you will lose 21.64 psi. That's just elevation and not friction loss through the 700 feet of service.

3. Where's the meter? In a pit down near the property line or in your house? Regardless, you'll probably lose another 2 psi through the meter and valving. The Meter is down at the street.

4. Someone mentioned a pressure regulator. You may or may not have one. No Clue

5. Age and composition of the water service may be a factor. Granted. Over 30 years old

6. Booster pump may be a solution, but adequate water has to be there on the inlet. The pump cannot create water, only a pressure boost. I.e. if you need 6 gpm, that amount at a positive pressure needs to be available at the pump inlet. (NPSH - net positive suction head, or, if the pump is not getting water Not Pumping So Hot). If your water service is too small, has diminished inside dimension (think clogged artery), has a valve partially closed or obstructed, etc. these will contribute to flow and pressure drop. Will have to have that checked.

7. Other factors that contribute to pressure loss are backflow preventers, which you may or may not have on your service. I am pretty sure I have a backflow preventer on my hot water heater.

Have you always had low pressure or is this a recent development? Do you know the water pressure in the house and at the street? Your water purveyor should be able to provide you with flow test results from a nearby fire hydant that would indicate pressures/flows in the street main.

. Yes, the water pressure has always been poor.