6.12.2008

Drip Irrigation for Home Gardeners, Part I: Getting Water

We recently completed the setup of a rainwater drip irrigation system for our garden, which feeds about 400 square feet of tomatoes, peppers, acorn squash, strawberries, sunflowers, herbs, and melon vines.

Several years back we bought a 1500-gallon cistern and placed it next to our house to catch runoff from the roof. Since that time we've had on-again, off-again problems with delivering water up the gentle grade to our garden, which sits in a small patch of pasture on the way to the road. This year I pulled out an old submersible pump and PVC assembly I had created several years back and had put away in disgust after having some problems with its functioning. Miraculously, it worked fine.

We also had a huge tangle of drip irrigation lines we originally used when we were gardening in a traditional row layout, before we switched over to raised beds. More on that in the follow-up to this post. Suffice it to say for today that the pressure from the 1/2-horsepower pump (or was it 1/4?) would have been too strong for the driplines, and either damaged the pump (backup pressure) or the lines (forcing too much water through them too fast). That was our theory, anyway. So we decided that we'd need to pump the water into something closer to the garden, and then gravity-feed it into the lines, with the pump off.

That's where our small stock of 55-gallon barrels came in - the same ones we used for our rain barrel. I discovered that the outlets at the top of the barrel had an inside thread that didn't go anywhere (walled off) and by drilling in carefully with a 1/2" bit I could turn the barrels' 4" lids into donuts that could have a hose screwed into it. After a bit of fiddling my father and I realized it would be more convenient to use a faucet instead of plugging the hose directly into it, as we'd have more options when the barrel was full of water.

We created a platform out of cinder blocks and the remains of some rough, handmade pine bookcases I had recently dismantled. The bookcases' sides have somewhat regularly-spaced strips of 4" board screwed to them which had held up the shelves, and almost seemed custom-designed for this project - they made great braces for the heavy barrels, which were already filled with water. More wood was used as a ramp to get them up in position.

One last bit of wisdom I lived to gain was that the top entry for each barrel, which I had cleverly drilled out to put a hose in, offered no way for air to get out of the barrel when it was being filled using that nice big pump. You can probably see the barrel swelling in this photograph. Luckily the barrel walls were very strong and Jenni noticed the issue before I burned out the pump motor. We now remove those top plugs completely and drop the hose into the barrel in order to fill it.

We really had no idea if 55 gallons of water was going to create enough pressure to drive water through our driplines, but it was. I'll describe and offer photographs of that system in my next post - basic drip systems are actually pretty easy to set up, offer your garden plants water at a rate they love, and can somewhat automate an otherwise labor-intensive garden task.

1 comments:

kenm said...

Essentially what you've made is the miniature of the classic municipal water tower. Pump uphill to storage, then distribute when needed by gravity. Ideally, the house could be situated on high ground and the garden lower, and the electrical pump could be eliminated.