Answers for Your Questions: Irrigation Edition

You wouldn't believe the e-mail I get. This special edition of Answers for Your Questions is all about the last few posts about the irrigation system. Have a question about Casa Decrepit? Send it to us.

Why did you design in so many zones?

I have a really obsessive-compulsive watering schedule for the garden, and I wanted to be able to control a lot of variables. Also, I wanted to even out my water use over time to optimize my use of the water supply, and the best way to do that is to have a little water going out all the time, rather than a lot of water all at once.

In addition, I'm growing a lot of plants with wildly disparate needs, like some plants that want no summer water at all, and others that need to be watered almost daily (I'm looking at you, roses). I don't see any good way to combine the zones for those plants without making somebody really unhappy.

What is the normal number of zones?

From what I can see, most small urban lots around here have four zones: front yard, back yard, front plants, and back plants. In the new, tight developments, there may only be one zone, because the yard is eight feet by ten feet. In larger suburbs or on larger lots with more complicated plantings, you see more zones, because there's a greater need for water.

Then again, most small urban lots around here have the most boring gardens you've ever seen. I think if you want a more complex garden, you are inevitably going to end up with a more complex irrigation system.

Do you really need such a complicated irrigation system?

Nobody needs an irrigation system at all. I could have planted only drought-tolerant natives and the garden would be fine. But I wanted something else, and for what I'm doing, yeah, some of this complication is necessary.

Also, I'm trying to reduce the amount of ongoing work I need to do. By making a very complicated system that just does everything, I avoid having to turn on valves manually, remember when the ferns were last watered, or drag hoses all over the place on a regular basis. I also can avoid having tubing run across paths, or in places where it will be tripped over or will catch up some rompy, stompy animal who is dashing through the flower beds.

On the Irrigation Tutorials site he says to use Class 200 PVC, so why are you using Schedule 40?

The main reason why I used Schedule 40 pipe was that that was the kind of pipe I could find within easy driving distance of the house. And that was the kind of fitting that was available locally, too. Your mileage may vary wildly, but that was 100 percent of the reason behind my choice.

What sprinklers are you using?

For the lawn I chose Rainbird 1804 heads (the "4" is for a 4-inch pop-up). I chose them because I went around looking at lawn sprinklers all over the place -- in residential neighborhoods, in developments, and in commercial settings -- and the ones in the best condition were Rainbird or Hunter. Rainbird were easily available locally with the types of nozzles I wanted, and there you have it.

In the beds I'm using a combination of Shrubbler and Spectrum sprayers (descriptions and so forth can be found on this page at Dripworks). As I've said, we have quick-draining sandy soil, so I needed sprinklers, and these two types offer the flexibility I need for my system.

In containers, I am using Woodpecker PC drippers. Because I don't have sand in my containers, so I don't need sprayers, and these are really great drip emitters.

How much is the system costing you?

I think it's right at about $1,000 for all the pipes and sprayers and stuff. Not including our labour, my design time, and the water I have wasted on testing stuff out. Once we add in the water tank and its pump, we're going to be in the $2,000 range. At that rate, this system will pay for itself... well, never. But in a drought year we will have water when nobody else does.

Is building the system harder or easier than you expected?

The physical part of it is about as hard as I expected: digging and cutting and all that is tedious work. The design part was fun and relatively easy for me, although I did have a bit of a fuss about which fittings I needed for the manifold.

The hardest part is getting ten-foot lengths of PVC pipe home from the store.

When do you think it will be done?

In mid-July, I think. I know it seems like that is a really long time, but I only have weekends to work on it, so work is going to go very slowly. Right now we're in trenching mode. Next weekend I will be laying pipe under the house and doing yet more trenching (I can't get enough of it). In the mean time, Noel is working on my controller.

I also need to deal with the whole water tank/water pump issue. I think I will be going to the water tank store in Atascadero next week.

What are all those pallets doing all over your yard? Did you buy that much pipe?

Ah. Well. The pallets. See, I have this great idea for making a couple of compost holders with them, wiring them together to make three sides, then growing vines over them to hide them from view. I really should just do that. They have nothing to do with the irrigation: the sod came on three of them and two are leftovers from the foundation work. I'd really like a sixth, but I can't bring myself to go scrounging for one when I haven't gotten round to using the ones I have yet. That's what the pallets are all about.

Technorati Tags: irrigation, landscaping

posted by ayse on 06/12/06