Water line size

[Creeksidelc]

Hi, I recently cross fenced our land and now am looking to run some waterline so we can have water in each pasture. i would like to run 650 ft from my main waterline to a trough that will service the back 2 pastures. It is less than 10 ft elevation change. Do you guys think that a 3/4 in pvc pipe would be enough or do I need larger. We have very good water pressure. Im also open to suggestions on other pipe material I just thought about pvc since it is pretty cheap. Thanks.

 

[cbcr]

We had to run water almost a quarter mile from the rural water meter to supply 2 houses. The line out of the meter was only 3/4 inch, but with some input from engineers, we up-sized to a 2 inch pvc line near the meter and ran to where it needed to split, then ran 1 1/2 inch to the first house, and finished going in with 3/4 inch pvc. Line at split going to second house dropped to 1 1/2 inch pvc to about 75 ft from house, dropped then to a 1 inch pvc and ran that to within 10 ft of house where we finished with 3/4 inch going in.

Never had any issues with low water pressure and there were a total of 4 bathrooms, along with laundry. Also had outside hydrants.

 

[dun]

I use 2 inch PVC for all waterlines that are buried. For above ground I use 2 inch polypipe. It isn;t just pressure it; also volume you have to think about. I've never complained about too big of pipe, but 3/4 inch has driven me nuts at times.

 

[bball]

Friction loss is your enemy when running pipe long distances...best way to minimize this is to increase your pipe diameter (as dun mentioned) and minimize bends, curves and direction changes as much as feasible while using as smooth a piping material you can find. PVC is fine, just don't overdue the glue at your joints to the point that you get glue boogers on the internal portion of the pipe. This will give you more friction loss at every joint. Good luck.

 

[Nesikep]

I think for 700 ft going 2" would be total overkill.. though I'd say 3/4" would be the minimum I'd want... 1" in PVC or poly should do.. if you go poly, try and find the connectors that go on the OUTSIDE of the pipe.. something like the Sharkbite connectors for Pex or air brake lines.

I think there are sites out there that give you friction loss per foot of different types/diameters of pipe.. try and find one and plug in some numbers.

Just as a total made-up example, 1/2" poly may have a 10 psi drop per 100 feet at 10gpm.. if you have a 50 psi supply, that means at the end of your 700 feet (70 psi loss) you would not be able to draw 10GPM with an open end.. going to 3/4" may give you a 4 psi drop per 100 feet at 10gpm, so with the same supply, you could draw 10gpm and still have 22psi (50-28), which would operate stock waters well... remember these are just numbers I'm making up to show how to use them.

If you have dirty water with gravel in it, DO NOT oversize the pipe too much or you'll get gravel buildup in it and unless you have enough supply flow and pressure, you won't be able to get it out!

 

[bball]

If it were me, I wouldn't go any smaller than 1 1/2". You only dig the trench once, and if something changes and you want to tie in, add a barn, etc, etc you will have the water pressure and volume available. The price difference from 1" to 11/2" isn't enough to justify going smaller.

 

[greybeard]

If you ever need to fill a sprayer tank out in one of the fields, that 3/4" line will be cursed at the whole time it is filling.

 

[wbvs58]

I gravity feed several troughs with runs up to 300m and use 1" rural poly pipe and have no issues. Only one trough is used at a time as the paddocks are rotationally grazed.
Ken

 

[bbirder]

I'd use 1-1/2" minimum on the long run. I'd also install a valve every 200 ft to be able to isolate a leak in the future.

 

[Creeksidelc]

Thanks for the replies. ill go minimum of 1 in but will get some prices and try and do a 1 1/2 in line.

 

[backhoeboogie]

Friction loss is your enemy when running pipe long distances...best way to minimize this is to increase your pipe diameter (as dun mentioned) and minimize bends, curves and direction changes as much as feasible while using as smooth a piping material you can find. PVC is fine, just don't overdue the glue at your joints to the point that you get glue boogers on the internal portion of the pipe. This will give you more friction loss at every joint. Good luck.

Exactly bball. Laminar flow is what you are looking for. Close all valves. Pressure will equalize. "Pressure" is not the problem. Flow is the problem. The larger the pipe, the better laminar flow characteristics. Every bend adds a K factor. If someone shows up with a saw to hack through your PVC pipe, shoot 'em. Shoot 'em dead. They just killed your flow. Irregular cuts put massive restrictions on flow. Use the right tools and make sure every cut is square.

The bigger, the better. 1/4 inch poly tube will give you the same pressure at the end of the line. Close the line off and put a gage on it. You'll see. Not much flow tho. LOL

 

[Nesikep]

First you gotta ask yourself how much water you'll want at the end of the line and how much pressure you need at that flow.. until you answer that you can't make any educated decisions...

Then go to http://irrigation.wsu.edu/Content/Calcu ... e-Loss.php and enter what you've decided on, and it'll give you a pretty good idea of the line you'll need.

I went with 20GPM and 700 ft, 30 psi pressure loss (so if you're drawing 20GPM and have a 50 PSI pump, you'll still have 20 PSI which will operate automatic valves fairly well), they come up with a 1.2" pipe, round that up to 1 1/4" and you're good.. bear in mind this is probably not accounting for the internal couplings you find on poly pipe, which is why PVC or the external couplers are better... A second bonus is that if anything ever gets into the pipe, it won't bind up on the internal coupler! (Don't ask how I know this)

 

[1982vett]

Hi, I recently cross fenced our land and now am looking to run some waterline so we can have water in each pasture. i would like to run 650 ft from my main waterline to a trough that will service the back 2 pastures. It is less than 10 ft elevation change. Do you guys think that a 3/4 in pvc pipe would be enough or do I need larger. We have very good water pressure. Im also open to suggestions on other pipe material I just thought about pvc since it is pretty cheap. Thanks.

Uphill or downhill? I had calves pull the hose off the float earlier this year that is on a 3/4 line about 900 ft long. Course mine is about a 50 ft drop. I had a garden hose with a nozzle hooked up on the same line. late in the afternoons when the cows went to water it began effecting water pressure in the house so I decided to close the valve to that line a bit to limit how much went down hill. I knew something was wrong when I went to water the garden....the hose was sucked flat.

I also have another line that is about 700 ft long. It is down hill then back up hill with probably the last 100 ft being uphill 10 or 15 ft. It is also 3/4 and does just fine but I use it only for watering cattle. I'm thinking that well system kicks on at 30 psi and off at around 50 psi.

 

[Creeksidelc]

It is 10 ft uphill. I'll contact the water company and see if they can give me an approximate psi at the meter to do some more accurate calculations for pipe size. After looking more into that black poly pipe in pretty sure I'm going to go that route. With the 300 ft rolls available I should be able to space it to where the only place there are joined is at my hydrants. There will be 3 water hydrants feeding troughs. Thanks all for the replies.

 

[John SD]

If it were me, I wouldn't go any smaller than 1 1/2". You only dig the trench once, and if something changes and you want to tie in, add a barn, etc, etc you will have the water pressure and volume available. The price difference from 1" to 11/2" isn't enough to justify going smaller.

+1. A general rule of thumb is that if you double the pipe size you quadruple the flow. IOW, a 2" pipe will flow twice as much water as a 1" pipe, all other things being equal.

All of my pipelines are 1 1/2", and I would not go smaller. I have used both PVC and HDPE pipe. The PVC pipelines change to 1" poly pipe at the tank valves. I have used hydrants on a few tanks but regret it and would not do so again. Keeping all of the plumbing underground gives you more options, and any above ground freezeless hydrant with a rod inside offers pathetic water flow rate at best. And a "freezeless" hydrant certainly isn't when used in late fall

On the HDPE water lines I used 1 1/2" valves and the 1 1/2" pipe HDPE pipe directly to the tanks. The water flow of the 100% 1 1/2" setup is noticeably better than the 1" poly pipe. especially when you get over a mile from the pump :idea:

Personally, I would not put a valve in every 200 ft as someone mentioned. Maybe every 2000 - 2500 feet, but I still see no real benefit and extra valves just adds to the cost and complexity. KISS, you're gonna hafta shut the water off to fix a leak anyway :idea: :2cents: