Drip-lines: How do they work? Advantages?

May 22, 2005 10:51 PM

Can anyone give me a good intro to drip irrigation? I'm fairly used to sprinklers, but I've heard good things about drip lines, and I'm wondering whether it's worth trying to switch over.

Things to address:
Advantages/disadvantages compared to sprinklers?
Can they be installed using PVC pipes attached to sprinkler timers? (We're in the final stages of running PVC pipes throughout my property, so the ability to connect these things to PVC pipes would be nice)
We have a new greenhouse built for my grandfather, and we're fairly clueless about greenhouse-type stuff. He wants to use it for starting seeds. There are 2 PVC hookups inside - would one benefit from getting hooked up to a drip line?

posted by sirion to home & garden (11 comments total)

The Israeli's are pioneers at drip irrigation and this page has links to a number of Israeli companies which specialise in it.
posted by PenDevil at 12:51 AM on May 23, 2005

I see mainly advantages, although I suppose it depends on your environment and what your growing. So, with the caveat that I live in South Australia, proudly the "Driest state in the driest continent", I can see mostly positives with drip irrigation.

Spray irrigation / sprinklers throw the water into the air. A certain percentage of that water will (a) evaporate in the air immediatly (b) land on leaves and evapoate from there. Sprinklers do look cool, and are easier but logic tells you it's always better to direct the water to where it's actually needed - the roots - and skip the middle man. So in the interests of water conservation, drip is the only way to go. And they certainly can be attached to normal PCV pipes, the same was as sprinklers can, indeed, without needing the "risers".

However: the disadvantage of drippers (and it's important in your case) is that it's pretty much one dripper per plant. In the case of seeds that's all a bit silly, and if you're raising the seeds in seedling trays it's really not going to work, and sprinklers are the way to go. The fact that you're in a glasshouse can be advantageous - there will be less loss to evaporation, and the sprinklers / misters will increase the humidity, making things easier on the plants.
posted by Jimbob at 4:02 AM on May 23, 2005

The big advantage of drip over sprinklers is you're supplying water to the plant where it's most needed, not just spraying it in the air. The only thing that can be called a disadvantage is you need to do a little planning to figure out where to put all of the fittings and drip emitters. In other words, no real disadvantages.

Off-the-shelf drip components aren't made to be used with PVC pipe. Instead, they use a softer pipe that can be punched to install the emitters. I installed some drip equipment last year to help start a bunch of plants in my yard and I connected the drip to my water supply using a garden hose.

A good source of information is and products is DripWorks (I have no connection with them other than being a customer). Besides their decent prices for equipment, they have a wealth of information on their website about drip irrigation. In addition, they offer a free design service and tech advice over the phone, though you have to pay for the phone call to Willits, CA.
posted by SteveInMaine at 4:09 AM on May 23, 2005

Drip Irrigation is best in circumstances where the air is very dry. So, if you live in the Southeast or southern Midwest, where the dewpoint is often in high 60s or 70s, most of the advantages of drip irrigation fade, and then your dealing with the costs. The one that doesn't fade is adding nutrient to the drip (which you can't do as easily or controllably with spray irrigation.)

In a greenhouse, where the humidty will build, drip isn't as useful (but is easier to set up.) Fixed overhead sprayer would offer many of the same advantages

You can connect to PVC, but you'd want something flexible for running to each drip outlet.

The place where spray irrigation fails is where the atmosphere is frequently dry -- Israel and the western Great Plains are the biggest examples. There, you spray a gallon into the air, trying to reach the plants, and much less than a gallon lands. Then, before it does you any good, a good fraction of that fraction of a gallon evaporates further. You raise the local humidty a tad (but it is still dry) and your plants are still thirsty, and you are now down a gallon of water. Not good.
posted by eriko at 4:43 AM on May 23, 2005

I used to live in an area in California where it was too dry to effectively grow anything without irrigation. My girlfriend and I put in a substantial graden with drip lines. We set up one feed in on a timer and then split that into 4 smaller lines that each had their own valves. The 4 smaller lines were a type of hose that was made to be plugged at the outlet end and with the drip lines connected to it via punched in ferrules that connected to 1/8" feed line or soaker hose. After some valve adjustment for to equalize pressure, it worked like a dream.

As far as hooking it up to PVC, you can connect anything to PVC with the right set of adapters. We went from a hose fitting down to the drip line and there are PVC hose fittings.

In a green house I don't think you'd get a big win, except for one thing: drip lines help eliminate powdery mildew which is fostered from sprayers.
posted by plinth at 6:27 AM on May 23, 2005

Just make sure your water supply is clean - filter it if necessary. Clogged drippers are a lot harder to spot than clogged sprinklers, and often the first sign is droopy plants.

Porous soaker hoses (made from recycled car tyres) work really well under mulch, and because they have so many holes they don't seem to suffer so much clogging.
posted by flabdablet at 6:30 AM on May 23, 2005

One advantage of drip irrigation regardless of where you live is that you water the plants, not the weeds. Lots of mulch and lots of Preen (although I won't touch the stuff) will take care of the weeds if you sprinkle. A friend of mine spent over $40,000 installing drip irrigation in an ornate garden (I guess this is where your money goes when you are a high earning, single, childless mid-50 something guy). He had nothing but trouble for the first year. Too much water was being applied, but since it is applied underground it can be hard to tell. I think some of the lines also froze and needed to be replaced. If you install this stuff work with someone you can trust to come back to tweak and repair the system.
posted by caddis at 7:22 AM on May 23, 2005

I love drip systems. I also love that the components are dirt cheap. I have drippers connected to an underground Schedule 40 PVC network.

Basically, if you went to Lowe's, or any irrigation supply store, you can find, with some effort, the necessary pieces that will connect a 3/4 inch PVC pipe to a piece of "funny pipe", the black tubing that is the base for the drip system, which can then accept the narrow tubing and drip emitters.

Once you start getting the hang of it it's really easy and tremendously gratifying.

I have dozens of trees and shrubs that also are on drippers that connect to my hose bibs. I installed a splitter at the bib and just direct the flow into the PVC network that runs hundreds of feet across my property.

Remember, for long runs you will have to use a larger caliber pipe to account for frictional losses. Funny pipe and certainly PVC should have no problem.

If you email me I can send a picture of the coupling pieces you need to hook the PVC to the funny pipe.

Also, every tree I have on a dripper is thriving and growing beautifully.
posted by docpops at 7:41 AM on May 23, 2005

It's easy to connect drip to sprinklers, there are adapters for the purpose (can't find a link quickly, but they are at my local Home Depot/Lowe's). We use both the passthrough kind (allows a sprinkler above it) and the "sprinkler head replacement" kind which has no passthrough. You can get these octopus-like things that have 4-6 metered 1/4" barbs for the small diameter hose.

My biggest problem is figuring out what the water needs of everything is.
posted by RikiTikiTavi at 9:25 AM on May 23, 2005

Our own mathowie posted photos of his recent experience with drip irrigation system.
posted by terrapin at 9:29 AM on May 23, 2005

Drip irrigation is better than sprinklers even in more humid areas, because the water gets to the roots, not just the leaves. I've had problems with overhead irrigation on plants with lots of leaf cover, because the water never gets to the ground under the leaves...it all runs off the ends of the leaves, and there's a ring of wet soil around the perimeter of the plant while the soil around the roots is still dry. If it's humid enough, the leaves never dry, and you can get leaf rot.

I usually use a hose end sprayer wand to water my plants -- that way I can get the ground, not the leaves. We also sometimes use a soaker hose, or for trees, a hose set at trickle. (I don't water much, though. The only trees that get watered are the new ones.)
posted by jlkr at 9:50 AM on May 23, 2005