Drip System Design Help Requested

17 years ago

Hi all. I'm setting up a drip irrigation system for four 4' x 8' x 18" intensively planted raised beds. In my typical, impatient fashion, I already designed a system, purchased all the equipment, and have the rigs for two beds put together in my basement awaiting installation. I had plenty of time to think things through while I was punching holes and placing emitters, and I'm not even sure the system will work. I'd really appreciate consideration of my design and any advice you all might have. I plan to run the system off a 3/4" city water faucet that has a 257 GPH flow rate. I think the pressure is about 62 psi. I'll connect an anti-syphon valve, filter, and a 25 psi pressure regulator, follow that with about 50 feet of garden hose, which will connect to 30 feet of buried 3/4" PVC pipe that runs along the beds. I'll route the pipe into the corner of each bed, and then run a 4 foot length of 1/2" blue stripe line across the top of each bed. Each blue stripe line will spawn four 8-foot 1/4" drip lines that will run the length of the bed. Each 1/4" drip line will have eight 1 GPH drip emitters. Total number of drip emitters is 128 (one per square foot). At unregulated pressure (62 psi?), 128 GPH is no problem, but won't the 25 psi regulator drop total flow to about 100 GPH? Is my 12" emitter spacing too close? Do I have too many emitters? Do I need a pressure regulator? I'd like find answers to some of these questions prior installing a complete failure and destroying what little confidence my wife has left in my gardening abilities. Thanks so much!

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Comments (5)

JamesY40
17 years ago
I am also in the process of installing a similar system for my four 4x8 beds. I would be interested in any help as well.
James
dxjprice
Original Author
17 years ago
Hey, James. I did some experimentation over the past few days, and I've changed my set up a bit. The rig I had worked fine, but I think it would have been too high maintenance since all 128 emitters would have to be staked off the ground. I'm now using 4 feet of 1/2" line at the top and bottom of each bed. The 1/2" lines are connected by five 1/4" hoses with built-in 0.5 GPH emitters every 6". I capped the ends of the 1/2" lines, and piped water into one of the lines between two 1/4" hose connection points. My city water bibb with a 30 PSI regulator has no trouble feeding all 4 beds. I just hope the emitter hose doesn't clog too often. What did you go with?
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hookoodooku
17 years ago
From what I understand, you shouldn't feed several emitters from one 1/4" hose.

The simplest setup for a 4x8 bed would be to use ALL 1/2" line and place emmitters every 12" directly in the 1/2" lines. That would make for only 32 emmitters and would likely still be overkill as other places (www.irrigationtutorials.com) claim that emmitters are only needed every 18". On an 18" spacing, you would only need three 1/2" lines down the length of the beds with only 6 emmitters each (total of only 18 emmitters).
JamesY40
17 years ago
I haven't begun installation yet, but was thinking more along the lines of what hookoodooku suggested. I have been reading a couple of books to get ideas, but so far all iave installed is the main line to where I will connect the valves, and the timer. My system will be elaborate as I will have a combination of drip irrigation and a mist system set up.
jumby
17 years ago
I'm in New Kent dxjprice, not too far from ya. I have line with drip emitters on some fruit trees I put in, and would hate to have to do that with the 9 raised beds I have, too much effort for me. So I'm putting dripline in mine and just daisy chain the beds together. I just put in 100' of dripline with built in emitters on my raspberries/gooseberries/currants and the 18" spacing wasn't all bad. I have some left over 12" line and I plan on using that and some of the 18" pieces. I haven't gone so far to trench and run supply lines yet, I just use a filter and regulator on a hose and take it to each area I need to water, that and a cheap dial timer and it works great. Once I have everything the way I want it I'll tie all the zones in together.