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Sunday, June 26th 2011, 12:43am

Thinking about a DIY sprinkler system.. getting started..

I purchased a house with a 15 to 20 year old system. It didn't get good coverage, the valves were basically buried in dirt, so I pretty much want to do it over. The good thing is that I already have a separate meter for it. To start I want the proper valves and backflow preventer for the front yard and will deal with the backyard later. I estimate that I'll need 5 or 6 zones in the front; and that I have somewhat low water pressure. My entire property is only 80ftx120ft, so not terribly large. The poly pipe that is being used is 1" wide, so I think that makes it 3/4" poly.

Currently I have a 3/4" copper that was converted to a 1" CPVC with a shutoff valve right before, which then goes outside into an old backflow preventer. (plastic, not metal) I can't tell what the 1" CPVC from the backflow preventer does because the valves are buried.

I was looking at this bronze backflow preventer: 800M4-QT

Seems messy though as I'd have to go from 1" CPVC to bronze, to CPVC and down to the valves. Are those conversions easy enough? Maybe even use a sharkbite connector as I think they can go from CPVC to male end to screw in to the preventer.

I guess my main question is, should I stick with the 1" backflow preventer? Should I get 3/4" or 1" valves? Or does it really matter what my PSI and GPM are? I'm getting a gauge next week, so I'd have numbers then. I'm thinking about having 1" CPVC coming out of the valves as "main" lines which then branch off when need to the heads with my current 3/4" poly tubing. (that i can reuse) Generally, how deep is the pipe burried in the yard? I was reading 8 inches was good. (I'm in Michigan, so we do get snow/ground freeze)

I thought I read that impact sprinkler heads work better with low PSI? Is this true?

Also, I wanted to try and make this, to make winterizing easier. The CPVC around the backflow seems to make this tougher though..

Thanks, Nick

Does it really matter if you use 3/4" valves

This post has been edited 2 times, last edit by "the3dolla" (Jun 26th 2011, 1:26am)


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Location: Metro NYC


Sunday, June 26th 2011, 8:46am

that winterizing page you linked is lame-oh to the extreme ~ better you read the instructions that come with a PVB


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Posts: 309

Location: Northern New Jersey


Sunday, June 26th 2011, 2:58pm

I insatlled my own small system successfully. You may want to try an on-line irrigation site just to learn the basics. They will even design a system for you. I used then came here when I had questions. That backflow preventer is a PVB, is what I used and I think one of the better preventers. If I were to put in another system I would use "better" valves.

As far as winterizing I used unions to install my PVB. Will take it indoors when the time comes. And I have a small compressor to blow out my 3/4" poly tubes.


Supreme Member


Monday, June 27th 2011, 12:27pm

Read through the Irrigation Tutorials. I would consider it a MUST-READ for any newbie DIY irriagtor. I'll grant you that it isn't the most easy read... you'll have to read it three or four times... so I suggest you print out a copy and keep it in the thrown room. You might want to also read through some irrigation books you can pick up at a library. But keep in mind, some of those books are designed for beginners and gloss over or short cut some of the meat you'll find in the tutorial.


Tuesday, June 28th 2011, 9:47pm

Thanks.. I have been reading that tutorial, I'm not sure yet what my PSI or GPM is yet.

I'll get the PSI from the regular hose faucet. (right by the irrigation PVC coming from my basement)
However, for the GPM, I should get it from the 1" of PVC coming from the house, right? Seems that not as much would come out of my smaller hose. (5/8")

Is there any harm with going for the 1" valves? They seem better in the charts I see.
I'm thinking about the CP-100 Rainbird or the Orbit 57101P
It seems that there is only less PSI loss if you have 15GPM or less; guess I need to measure that. Does that sound right, just need a little confirmation!!! Thanks

I wonder if I can use any inline valve to run a few hundred feet of soaker hoses? (maybe a flow control one) Seems like there wouldn't be enough GPM though.

I don't know how that winterizing article I posted had a bad setup. Kind of hard to believe with nothing to back it up other than "it sucks".


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Posts: 309

Location: Northern New Jersey


Wednesday, June 29th 2011, 9:22am

PSI from the faucet isn't useable psi. You really need to read that tutorial or do the design service, it's free and you will lean allot.

As far as winterizing. Use unions to remove the PVB and bring it inside. Then blow the lines carefully with a compressor. Or for the first year call in a pro and watch them do it.

You mentioned concern about going from cpvc to brass, etc. It's simple. I learned allot from a retired plumber working at Lowes. Or just google how to connect cpvc, etc.

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