Quick Question! Trenching water line to barn

[barnfield]

Quick question:

This week I am planning to run black poly water line out to barn and pastures from the house.

Will be starting from a 3/4" copper line from the pressure tank in the basement (& installing a shutoff valve), then go through the basement wall, and then trenched 3 ft deep all the way out to the barn.

Longest run is a good 550 ft. or so.

QUESTION: What diameter of polyethylene to use? 3/4"? 1"?

Fyi, there's 1" black poly from the well to the pressure tank in the basement of the house, then from the pressure tank to the spot where I can tee off from is 3/4 copper. The hydrants themselves are 3/4" diameter inlet.

Is there ANY benefit trenching 1" poly over 3/4" if both the source and the destination are essentially 3/4"???

Will my water troughs fill up any faster?

Thanks!

[Jimbrown]

I don't know if it will flow any faster but i would use 1 in. I find at least it seems to be stronger and less likely to kink or get holes in it. 550 ft is kinda a long ways for 3/4 in.

[rifflerunner]

Why not just tee it off at the well instead of bringing it out the house wall? I did this exact same thing last year and just teed it to the barn from the run between the well and the house. Your pressure tank will still supply the needed pressure to get it to the barn. I used 1" and had to go almost 300'.

[barnfield]

rifflerunner, doing so would involve crossing the underground power to the barn from the pole on the street.

Also, a water shutoff valve in the house seems like a nice idea, anyway.

[honeycutt]

If your pressure switch is at the pump do not put anything between the pump and the tank. This will give you problems in the long run. The pump will tend to keep cycling while using the part that is installed between the 2 and the service life of the pump will be shortened.

[barnfield]

honeycutt, the water line to barn will be after the pressure tank.

[arrow]

This has more to do with pressure rate than pipe diameter. Theoretically, even a 1' will not fill faster than a 3/4" if there is not sufficient pressure to move that increased volume a 1" pipe will provide. On the same line of thinking, increasing pressure at the source, can make a 3/4" line fill as fast as a 1" line that has less pressure. If you do not have sufficient pressure for a 1" line, using the 3/4" will not be a problem. If pressure is forceful enough, you'll see water coming out harder as a result of the reduced size outlet but the volume will always be governed by the smallest pipe diameter. So unless you increased pressure at the source, the tank will not fill faster with the 1" line coming into a 3/4" reduction.

[J_J]

Crossing the electric line should not be a problem. Check with the utility company and verify the depth. That electric line should be down about 36 in , and the water pipe should be below the frost line. I would still use 1 in, and put a bladder tank at the barn.

[barnfield]

Waterline must also buried at 36 inches in my area to be well below the frost line.

[DavidPerry]

Small diameter pipe reduces the flow through long distances due to "hydraulic friction"

Hazen-Williams Equation - calculating Friction Head Loss in Water Pipes

At 5 gpm, 1" ID PVC will have a drop of 1 psi / 100ft while .75" ID will have a drop of 3.9 psi / 100FT