Sprinkler piping- use PEX or schedule 40?

[plowhog]

I am going to run some 1" sprinkler lines at my Nevada property. These will only be operational in summer/fall and I will include drains so I can winterize the lines. Someone here told me I need 19" of depth for schedule 40 PVC due to freeze issues. But my lawn had schedule 40 at about a foot and those never froze.

Someone else recommended PEX. Apparently PEX can handle some amount of freeze/thaw and still survive, whereas schedule 40 will break. I've never used PEX but recently had it installed in my new garage and it seems fine. Just not as rigid as schedule 40 which is fine. I know I will need a crimping tool if I go with PEX.

Have you used PEX for sprinkler lines, and what are the tradeoffs of PEX vs schedule 40 PVC?

 

[mcfarmall]

Neither. Use the black flex stuff that comes in 100-200 foot coils from your local big box home improvement store...it's sold specifically for underground sprinklers.

 

[RNeumann]

PEX wasn’t designed for exterior and or underground. PVC or HDPE (some would call it “poly”) is the preferred method.

 

[newbury]

Have not used PEX for sprinkler lines. Around here black poly is the most used.

If you go PEX tools are fairly inexpensive on Amazon buts clamps are a lot cheaper at places like https://www.supplyhouse.com

 

[plowhog]

How do you mate up black poly with schedule 40 PVC? Seems once I adapt to poly I can stay with that. But I think the plumbing for my underground valves, etc. should be schedule 40 PVC.

 

[RNeumann]

How do you mate up black poly with schedule 40 PVC? Seems once I adapt to poly I can stay with that. But I think the plumbing for my underground valves, etc. should be schedule 40 PVC.

Poly Fittings For Lawn Sprinklers & Irrigation Systems

Normally you don’t want the PVC to be the female threads (fittings split or leak) but with these fittings I don’t know what is best practice- a call would probably answer that. Otherwise I’d put stainless or brass couplings (making both PVC and poly fittings male)- especially on the Supply side of the valves.

 

[BoFuller]

I have schedule 40 coming out of the house and then the black poly going out to the trees. You can get adapters at HD or Lowes for connecting the two together.

 

[EddieWalker]

Black poly is used for sprinklers when you don't want to spend the money for schedule 40. It's junk and you will never stop doing repairs to it. Around here, it's what the low end guys use. I'm not familiar with PEX being used for sprinklers, and I don't understand what the advantage would be if you are below your freeze line.

When designing a sprinkler system, the first thing you need to figure out is what sprinkler heads you are going to use based on how much water pressure you have. Usually it's five full heads per line with 60 pounds of pressure.

Then you need too figure out your path to get there. The problem with poly, and probably with PEX is all the connections that you will have to make at each sprinkler head. The poly pipe uses a very cheap fitting that fail all the time. PEX would mean using brass fittings for your sprinkler heads, which wold be pretty nice, but add up cost quickly. PVC has everything you need, and once properly primed and cemented together, will never come apart.

Remember, PVC requires purple primer to soften the PVC and start the chemical bond between each part by the cement, which melts/welds them together. Any other method is just a glue that tends to fail in underground conditions. Glue is OK for drain or vent lines above grade, never for anything under pressure.

 

[RNeumann]

One of the toughest parts about plumbing is understanding the 100s, if not 1000s of different types of “pipe” and “fittings”. The slang terms don’t help as they tend to get intermingled.

 

[plowhog]

Black poly is used for sprinklers when you don't want to spend the money for schedule 40. It's junk and you will never stop doing repairs to it. Around here, it's what the low end guys use.

I have the budget to do it right, and since my dad was a plumber I am very familiar with PVC schedule 40. I've installed PVC from 3/4" to 6" for a penstock to my pond. So maybe schedule 40 is the way to go.

One limiting factor is that I don't know how much volume I have to work with. My situation is a 1 1/8 main line from the well, running uphill to my garage. Just outside the door, it has a T fitting and a 1" connection for my outside irrigation. The wild card is how much water the well can push uphill. I am considering installation of one 1" line to a 1" sprinkler, and then running that and see how it goes. Then maybe add another, and so on. If necessary I could run the sprinklers one at a time if the volume is insufficient.

I am also unsure whether to put an autodrain at the last fitting at the lowest point in the system. The alternative would be a pvc ball valve instead, accessible through a christy box. The ball valve for winterizing seems cheap and bulletproof. Not sure how reliable the autodrains are.

Finally, for several reasons I am probably only going to bury this maybe 12" down, which is within the frost line. So I need to have solid reliable ways to flush/winterize it.