drip irrigating tree lines

Seattle, WA


I have just setup a drip system for my greenhouse, two gardens and the grapes I will be planting next week. I have tree lines on my property andf also roses. I want to continue with a separate drip system for these plants, the trees are in lines 300 yards long and also 100 yards long. I have a large amount of 1/2" PVC pipe given me and have used it on my previous projects and it seems to work great.

My trees are on a 9 degree down slope from my source of water supply, event though the distance is quite long, could I utilize the 1/2" pvc over these greater distances with no problems? What pump would you recommend?

Thanks in advance

Las Vegas, NV(Zone 9b)

What I've learned so far from this link ( http://www.irrigationtutorials.com/#sprinkler ) is that it's gallons per minute (or it it hour?) that is the big ? . Then, how many trees you want to water at a time. If you get 55 gals an hour and want to water 55 trees? Then one GPH emitter per tree for one hour would give you one gal per tree. So as long as your 1/2" PVC can carry enough water for the trees you want to water, you're golden.

The link is what I'm working from. As far as a pump goes, the link addresses that. Sounds like you have a well. I'm only a city slicker. On the bright side I have 55 PSI from the hose bib.


Sacramento, CA(Zone 9a)

Don't most drip irrigation systems advise that you attach a PSI converter at the hose bib though to reduce the PSI to about 25-30?

Las Vegas, NV(Zone 9b)

That sounds right. I only chose 55 because it's what I have from my hose bib. I guess it was a bad example.

Everett, WA(Zone 8a)

>> My trees are on a 9 degree down slope from my source of water supply,
>> the trees are in lines 300 yards long and also 100 yards long.

The tangent of 9 degrees is 0.158, or the sine is 0.156, so I think a 300 yard run would have a 140 foot drop. Is that possible? It seems like a LOT of drop.

I think one foot of water depth adds 0.434 psi, so a 140 foot drop would add 61 psi, probably doubling your water pressure at the bottom of the hill.

If your water pressure at the faucet was 55 psi, you would have around 116 psi NOT counting "water hammer" when first filling the pipe. Can joins in PVC take that much pressure?

>> What pump would you recommend?

No pump, just a series of water-pressure regulators (reducers).

25 psi equates to 58 feet of drop (122 yards of run). You might need a pressure reducer every 100 yards or so even if you space out the drippers enough to account for pressure varying from 50-75 psi (or 25-50 psi).

Barely possibly, if you have a known and constant flow rate, you could drop the pressure using some kind of oriface in every other pipe join. But I think the sizes would have to be larger as you wnet downhill, since the flow rate would drop off.

I don't have any experience with irrigating on slopes, so don't take my word for it.


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