Running a new water line-need help in sizing it.

[bear]

Everything is based on starting pressure at the main. 60 psi is not alot to start with on a 3,000ft. service line. Where we are, the main pressure is about 125 psi. You can run long distances with smaller supply pipe.

At 60 psi starting pressure, the problem will be when you get to the house. Depending on how long the runs are in the house and how long the lines are going to the yard hydrants. Friction loss will build up quickly in those smaller lines.

When you hook that garden hose up at the end of that 1 1/2" service, pressure will not be more. You will have increased velocity with the smaller line but the pressure will be the same, and if the hose is very long the pressure will be less.

Increased velocity sometimes gives us a false sense of higher pressure but the volume that can actually be acquired through smaller line and increased velocity is less.

You can fill a 5 gallon bucket alot quicker with a hose and no spray nozzel than you can with a spray nozzel adjusted to high velocity spray stream.

There is nothing cheap about running any size line 3000ft. and you usually only have one chance to do it right.

The physical characteristics that allowed 2000ft. to work may be totally different than this situation. Every piece of ground is a little different.

Yes, a well may be cheaper

Bear

 

[kenojoe]

I built my house 7 years ago and the plumber used 2" line. Pipe runs 1200' and drops about thirty feet from the meter. I am on the second highest point in the county and have good pressure. I had the plumber put in a pressure regulator because I had to much pressure to suit me. Looks like some pretty good info. in the other posts. I would think the local plumber might have an idea of what the local system pressure is and could shed some light on what size is right for you.

 

[cowsrus]

The water line that runs to the house now is a 3/4 galv. pipe that was put who knows how long ago and we only have about 20 psi at the house now so anything i do is going to improve my situation. The city is putting the new meter in a different location and that was why i was trying to figure out if i would benefir from the larger line with a small tap. I really appreciate all the good advice you guys have given me and i know that the bigger the better applys here. Thanks
P.S. We don't have good water here or i would dig a well.

 

[bear]

Cowsrus, if you are going to run a smaller line to the house, another option would be to set some type of storage tank at the house and then pump out of the storage tank to increase pressure. You would have to install a backflow preventer before the storage tank.

Bear

 

[Angus Cowman]

This option might actually be cheaper than running a 3 or 4" line
use a 300 or 500gal poly storage tank and it wouldn't take a very big electric pump to supply 50psi to the house
I would talk to a couple of plumbers or mechanical contractors and ask them about these options

 

[backhoeboogie]

Go back and look at RAB's post.

If your house outlet is level with the supply outlet 3000 feet away, the pressure will be the exact same. Stick a gauge in there and see for yourself if you don't believe it. Close the water flow and the pressure will be equal. If you are downhill, add one psi in your favor for each 27.71 inches. If you are up hill, subtract 1 psi for each 27.71 inches.

Flow is your issue. K factors for pipe include friction factors for the type of pipe you use and there is more to calculate than you could imagine. The Reynolds numbers for the 3/4 inch supply don't even need to be considered in your calculation. When you open the valve at your house, flow is what is going to affect you. Close the valve and the pressure will again equalize.

To attempt to put it in layman's terms, water flow is in the center for most pipe with the outer edge consumed in friction. The larger the pipe, the greater the flow capability because you have more center flow capability. Each bend in the pipe adds K factors. Keep the pipe as straight as possible.

A storage tank with a booster pump connected to a pressure tank is your best bet.