underground water lines, what size plumbing

[aczlan]

As for the adapters, Grainger lists a 10 pack of connectors that go from a 1" male barb to a 3/4" male NPT for $13. Those should work as long as the pressure stays below 150PSI and the temp between -80F and 200F.
See: Adapter, 3/4 In Thread Size, PK 10 - Polyethylene Tube Fittings - Fittings - 4EMW3 : Grainger Industrial Supply

Aaron Z

 

[s219]

I have done a lot of irrigation work in my yard, including using various size pipe. I'm also a mechanical engineer that works in fluid dynamics. I really encourage you to go with the biggest practical pipe size. I used 1" mains everywhere. It doesn't matter what the pipe size is upstream or downstream -- if you have a long run to make, then use as big a pipe as possible for that run. It's especially important if you are marginal on GPM or pressure, as the bigger pipe will really help preserve your capacity. Small pipes will eat it up.

You can do some basic math to see the benefit, or consult a design table. But here's a rule of thumb -- for a given GPM and a pipe diameter D, the losses in a pipe (due to friction and things like elbows and fittings) scale like this:

Loss ~ GPM / D^4

Looking at that, every doubling of diameter will reduce the loss by a factor of 16, which is a HUGE effect. Or put another way, every time you cut pipe size in half, losses go up by a factor of 16. So a 1/2" pipe will have 16 times more loss than a 1" pipe. There is less difference between 3/4" and 1", but the 3/4" will still have about 3.2 times more loss than a 1" pipe.

Losses will eventually restrict the flow enough to reduce the GPM, so that becomes a second effect.

 

[boggen]

an attempt to go over pump curves, and giving an example of difference in pipe size and friction loss.

see attached diagram...

again below chart and numbers are only an example and will most likely not be near your setup. but hopefully help get idea across of things.

 

[J_J]

v8only ,

Is your water at 33 ft , and to your house considered drinking water quality?

 

[profnohair]

v8only ,

Is your water at 33 ft , and to your house considered drinking water quality?

My well in Loranger, LA is 30 feet deep and was tested by the state and taste fine. They will not issue an electrical permit without testing the water.

Profnohair

 

[STROIL]

Just wanted to share one quick thing on this topic. I had county run to my property, which involved them running a pipe to a new meter under the county road to my side of the property...then it was my responsibility (and my expense) to run whatever pipe I chose to my dwelling (a barn, in this case). The barn was 550 feet from the new meter. The water company guy strongly reccomended I use at least a 1" pipe. He also told me a tip. He said a lot of people use 1.5" schedule 40 pvc, primed and glued. For as long as that line would last (which could be indefinitely), you get ridiculous flow rate. It's easy to work with and not that expensive. But here's the big tip. He said if that ever fails, you have a ready-made conduit through which you can pull/push 1" pex or polyethylene tubing through with EASE, and renew everything easily.

I put the 1.5" schedule 40 pvc in a trench 30" below grade four years ago, and have had no leak. I put a pressure gage on the line, so I can monitor the pressure (and potentially indicate even a minor leak). No leaks in 4 years and I have flow rate out the wazoo.

 

[v8only]

that is what i am told yes.

 

[jagyzf]

Well i am told that my well supports 20 GPM @ 33'. To fill a 5 gallon pail at my hose bib at the house it took me 120 seconds to fill so my GPM is quite low and inorder to keep my "new" lines pressurized I am told that my current pump will not be able to keep up?

When you tested this was your well pump running? This could just be the flow rate of the system you were drawing from. Somewhere you should have a pressure tank that has a reserve of air and water it in. This air is what is pushing the water through the home, not your pump. Otherwise every time you needed water your pump would cycle on and off, and the water would be surging. The only way to know the flow rate of the pump is to either know what pump it is, or test right off the line coming into the house with the water shut off to the rest of the system. In other words to take the pressure tank out of the picture.

Also should you decide to tie in to the line between the well and house make sure that you don't have a check valve between the house and well. Many systems I have seen do have a chack valve right before the pressure tank to keep water from flowing back down the well, even though there should be one in the well. many times these fail over time so a new one is added near the tank.

Hope this helps.

 

[wrooster]

Well i am told that my well supports 20 GPM @ 33'. To fill a 5 gallon pail at my hose bib at the house it took me 120 seconds to fill so my GPM is quite low and inorder to keep my "new" lines pressurized I am told that my current pump will not be able to keep up?

You can't accurately measure available well flow rate by testing at a hose bib connected to 1/2" copper.

Wrooster

 

[v8only]

ok here is some new information:

i got my new GPM measurement from a hose bib right before it goes into my softner/pressure tank system in the basement: 30 seconds to fill a 5 gallon pail. Talking to my plumber who set up my well he is telling me my pump is a Goulds 10GS05412 four inch submersible well pump. This pump is a 10 gallon per minute ½ HP 230 volt.

So with this new information where do i start?

I did some of the Design data form information that i knew anyway and here is what i got:

Dry method:
1/2 HP pump
Dynamic water depth: 33 feet
Elevation difference: 10 feet (water line from basement to new irrigation system manifold)
Elevation head: 43 feet
Design Pressure: 50 PSI
Design Head: 115.5 ft. Hd
Total Pressure head: 158.5 ft. hd.
Initial Design flow 6.8 GPM

Wet method:
design pressure: 50 PSI
Inital design flow: 10 GPM

NOW the reason for the different in my opinion is that the elevation difference between me doing the test was 0 as i will not have to rise 10' to get the water out of the house as i got the water directly from the basement.

Pressure loss table: (keep in mind there is alot i dont know and I did alot of estimating which will be noted below:
water meter: 0 PSI
backflow preventer: 3 PSI
filter: 0 PSI
house mainline: 1 PSI (1" mainline from well into house is approximately 10' long, then from mainline to new manifold will be about 20')
irrigation mainline: 24 PSI (1" mainline from manifold to house bibs will be 1 line tied together for a total of 880')
valves: 5 psi (ball valves at manifold)
Elevation change: 4 PSI (from basement up to ground level outside is 9')
sprinklers heads: 0 PSI
Laterals: 6 psi (to keep maximum 20% of spinkler head value above????)
Total PSI: 43

SO if the above is correct my design of 50 PSI will work as my total pressure loss is 43 PSI.

What do you all think?