1400 foot water line (update)

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TX Hill Country

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Hi folks,

I previously got helpful advice from a 2021 post here: https://terrylove.com/forums/index.php?threads/1400-foot-water-line-in-hill-country-tx.92723/

Driveway is now in and I'm finalizing waterline choices. Planning on using rainwater collection tank for house, so the house waterline may never be fully run but who knows. For irrigation and house line I have a 325ft trench open and about to bed the pipe in sand and cover in the next week.

I've been using the Hazen Williams calculator here: https://www.engineeringtoolbox.com/hazen-williams-water-d_797.html to inform me, it's been very helpful to understand my situation where I drop about 80 ft of elevation in the first 600 feet.

I plan to install irrigation to temporarily water about 30,000sf of disturbed soil (required by the local authorities) to regrow native grass. Long term I'll use much less water (drip irrigation) but will be helpful to me to have sprinkler mainline available in places. The 325ft trench is 30" deep, I will try to hand bury another 600ft a few inches to somewhat protect the sprinkler mainline, laterals and sprinkler wiring from critters that might chew on them.
Posting all this to get comments if anyone sees me heading in a bad direction. I could upgrade the water meter at $$$'s to a 1" meter but I'd prefer to stay within the gpm of the existing meter.

The suggestion in 2021 to use polyethylene was been great but took me awhile to locate it at local waterworks supply houses. Regular plumbing stores never heard of it, it's similar to pvc cost, I have it on 500ft rolls, and plan to use connectors I've never seen before SDR9 CTS 'Ford Pack' compression fittings with stiffeners. They are pricy ($50 per fitting) but can be removed, reworked etc and apparently are commonly used by municipalities for long underground runs.

I *think* I have the math right, for the 325ft that will be trenched, I'm running (2) 1" poly lines, so for the irrigation with a design point of 8gpm there will be only 4gpm flow in each line, and as the image below shows there should be about 17psi pressure loss running 4gpm in 1" SDR9 poly 1400ft. That will more than be offset by the 80ft elevation drop which will increase my static pressure by about 35psi.

This has been an interesting project so far, and I'm winging it for some choices such as teeing off the two SDR9 poly lines for a 400ft irrigation branch. If I get the 'manifold' wrong I can replace it since the SDR9 fittings can be removed. For sprinkler heads I plan to use 180deg rotors about 2gpm each so 3-4 heads per zone, and I'm running enough wire for 32 zones.

Happy to answer questions - heading out to fill trench with a base of sand (3") if it's dry enough to use the skid steer, got .5" of rain yesterday. Tomorrow should be 75deg and sunny and I'm hoping to unspool the 500ft rolls of SDR9 and lay in the trench, should work much better when the poly is warm I expect ;-)






water lines house and sprinkler Dec 8 2024.png


Hazen Williams Calculator.jpg
 

wwhitney

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Curious why you have chosen to run two parallel 1" lines rather than say a single 1.5" line?

The pressure loss per unit length at a given total flow rate (half in each parallel 1" line) is about half as much for the single 1.5" line.

Cheers, Wayne
 

TX Hill Country

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The biggest reason is how difficult 1.5" is to manhandle versus 1" when I'm working by myself, especially this time of year. I think the cost is also less, the larger lines in pex seem to get crazy expensive. Also with having 4 1" lines total I have some redundancy in case of future leak, and since I don't know how the project will ultimately unfold I could use three of the 1" poly lines for the house and leave just one for irrigation once the native grasses are established. Good question.
 
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