Context:
I'm putting in shallow (14" deep) water lines 500ft from my house to gardening areas where they will supply several hose bibs for take-off points for drip irrigation. I was thinking PEX, but the pressure drop would require at least 1" and that gets expensive, so now I'm considering regular black poly instead (PE4710) which I can get in 1" or 1-1/4" at a much cheaper price. I cannot backfill with sand, it'll have to be the soil I trenched out, which does have some rocks, so durability with rocks pressing against the pipe is a consideration.
Question:
What are the most reliable fittings (within a reasonable price range) for black poly to NPT adapters (to connect to galvanized tees and/or elbows for each metal riser) that are least likely to develop leaks or crack over time? PVC fittings sound brittle to me, insufficiently tight and maybe easy to crack by overclamping? I like the sound of metal barbed fittings. I want this to last for many years without needing repair. I've seen videos of folks sweating the pipe using metal barbed fittings with hose clamps, but I can't find any such metal fittings online that clearly state they are meant for black poly.
Or would anyone suggest I discard the poly idea and go with the more expensive 1" PEX? I do know what fittings I need for that.
Best Answer
Polypropylene fittings work well, based on long experience, and are not brittle. You can get bronze if you really want to, or stainless steel these days.
If you are dedicated to metal risers, the internet (but for some reason not most local suppliers) has stainless steel threaded pipe and fittings (priced not too dear) due to the lead in galvanized pipe.
Schedule 80 PVC can also be threaded and won't become a rust bucket as galvanized does (yes, it does, the galvanizing has a very temporary impact on corrosion in service, as an observed fact) or you can use a suitable rot-resistant post and attach the black poly to it for another (and probably least-cost) rust-free option.