Drip Systems: Ten Pretty Good Ideas

Jack and Jill went up the hill,
To fetch a pail of water.
Jack fell down and broke his crown
And Jill came tumbling after.

Poor Jack, sad Jill. They were probably fetching water for their garden. Now with Jack laid up with a head injury, and Jill dealing with the insurance company and the hospital's billing department, the garden is probably going without water. Alas, all those lovely flowers withering in the summer heat. Whatever will Jack and Jill do?!? Well, no one in our house suffered from falling down the hill, but with two of us working and two kids we had to do something. After all, if you miss just one watering cycle during a week of ninety degree weather you have fewer plants to look after. And, unless I've missed something, the goal is to grow plants.

To cope with the task of watering, I have installed a drip irrigation system. Evolving from humble beginnings "the drip system", as it is known, has grown to a network of pipes that water almost every flower and vegetable bed in the yard as well as several dozen trees and shrubs and ALL the roses. Because all these plants haven't shrivelled up and died from lack of water, people assume that I must know something about drip systems and so I was asked to write this article. So bear with me dear reader and I will give you the ten pretty good drip ideas.

A Brief Introduction to "Drip Systems"

For the un-initiated, a brief introduction to drip systems may be in order. (The more advanced students may skip ahead to the next chapter.) A drip irrigation system is a system of pipes, connectors, and emitters (or "drippers") that allow you to put fairly exact quantities of water exactly where you want them. Although I've seen some literature that says you can bury these system, all the ones that I've encountered have the pipes running on top of the soil or buried only under a layer of mulch. It also makes maintenance and expansion easier, since access to the pipes is easier. Like a lawn sprinkler system, a drip system may be divided into separate watering "zones". One application of different drip zones is when there are different plants on the system that require different watering scheduled. A typical zone consists of a main "feeder" pipe (usually the 1/2 or 3/4 inch black PCV pipe) that gets the water to the flower beds, "spaghetti tubing" (1/4 inch vinyl tubing) that takes the water from the "feeder" to the plant, a dripper that meters out the water and the connector thingies that let you put these things together. Additionally, the drip system may also include a timer/controller, a filter, a pressure regulator and an anti-siphon valve.

The drippers (a marvel of fluid engineering) are rated at how many gallons per hour (GPH) drip out of the end. The three flow rates that I've seen are 1/2 GPH, 1 GPH and 2 GPH. Additionally you can get: "drip line" which is 1/4 inch spaghetti tubing with drippers embedded in it; "laser line" which is 1/4 tubing with itty-bitty holes "drilled" into it; and various forms of miniature sprinklers.

Most stores that carry sprinkler system products also carry drip irrigation products in varying degrees of completeness. Oddly though, they typically aren't in the same location within the store. I've had the most success at HomeBase and an irrigation supply house outside of Boulder called Western PIPE.

And with that whirlwind introduction behind us, let's get on with...

The Ten Pretty Good Ideas About Drip Systems.

I. Use parts that are easy to get.

When the first phase of "the drip system" was installed, 1/2 inch black poly pipe was used to get that water from the main feed to the drippers. Later, when repairs were needed to that part of the system, the appropriate parts for 1/2 inch PVC pipe were very difficult to find. On the other hand, since it is commonly used for lawn sprinkler systems, parts for 3/4 PVC pipe seem to be very easy to find. Since then, all new zones use 3/4 inch PVC pipe for distribution to the drippers.

II. Don't install the drippers like this.

In the beginning it was thought that inserting the drippers directly into the feed pipe (3/4 inch PVC) was a good idea. Then a piece of 1/4 inch spaghetti tubing could be put over the output of the dripper so that the water ended up at the plant. This saved a ten cent connector that would otherwise have been needed to connect the 1/4 tubing to the feed pipe. This was not a correct thought, and having spent a month at a labor camp, I now have only correct thoughts about dripper installation: Unless the feed pipe runs exactly past where the water needs to be, then the 1/4 inch tubing should be connected to the feed pipe (with a 10 cent "barbed" connector) and the dripper should be connected to the other end of the 1/4 tubing and placed where the water is needed.

III. Use good drippers

There are three types of drippers: pressure compensated, turbulent flow and cheap. The first two types cost twice as much as the third type, but give a more regulated flow of water when the water pressure varies. They also tend to be self cleaning, for the most part, while the third is described as "easy to clean".

IV. Use a pressure regulator

Once upon a time, I did not use a pressure regulator on my system. (Heck, the house water pressure was just enough to make one sprinkler head go, provided you didn't flush the toilet.) Then last summer I had sections of 1/4 inch tubing actually popping off the barbed connectors that held them to the feed pipe. At first I suspected the new brand of tubing that I was using. But then I discovered that the city had increased the water pressure to the neighborhood. (Ooooo, now I can run a sprinkler and flush the toilet.) Adding a pressure regulator at the water source fixed the problem.

V. Use a filter on each zone

You will want to include a filter (after the zone valve) for each zone in your system. Since these filters allow water soluble fertilizer to be placed in them, you can fertilize you plants with your drip system. Unfortunately, you actually have to go and put the fertilizer in the filter. A means of doing that automatically hasn't been invented, yet. If the filter is placed before the zone valves then only the first zone in the watering cycle will ever get any fertilizer.

VI. Know your zone valves.

The flow rate in a drip system (1/2 to 2-GPM) is significantly lower than that of a sprinkler system (3 to 12-GPM). Ordinary zone valves, designed for the higher flow rates of sprinklers, will not operate reliably on a drip system, failing to turn off when the timer tells them to. Fortunately there are automatic zone values that work at these lower flows. When choosing a zone valve, look at the specification. These will indicate the minimum flow rate for the valve. (This is one of the areas were the folks at Western PIPE were quite helpful.) Keep in mind that it takes 60 1-GPH drippers to equal 1-GPM.

VII. Don't mix watering schedules

As tempting as it is to "just run a dripper or two over from this zone", DON'T. Pay attention to what you are doing. Does the zone that you're hooking into have a watering schedule that fits the plant that you are adding into it? I didn't, it didn't and now I'm at risk of loosing an ash tree.

VII.Use good quality parts.

I'm big on brand loyalty. If I find a brand of product that does what it's suppose to do, reliably and at a fare price, then I will stick with that brand. I tend to always use the same brand of drippers, timers, valves and spaghetti tubing. But I just can't seem to get 3/4 inch PVC pipe and the related connectors from the same manufacture more that once. And not surprisingly this is the area that gives me the most grief. So, when you buy fittings for your drip system (or for that matter, your sprinkler system), always check to make sure that the parts are well made.

IX. Use a timer

Unless you have some incredible ability to always remember to turn your drip system on (and then off) on a regular schedule, you will forget. Trust me, I've been there. Both cases.

The initial "zone" valves that I used were manual valves. They are now automatic valves that are designed to handle the low flow rates associated with drip systems. Each zone valve is connected to a sprinkler controller that controls the watering schedule for each zone. This is one of those areas that you want to plan ahead. The question to ask is: can the controller give you the range of watering schedules you need (now and in the future)? For example, I have some zones (roses) that get 2 hours of water every third day, and other zones that get 30 minutes of water three times a day (veggies) and still others that get only 15 minutes of water three times a day (annuals). The only controller I could find at the time that could do all this was a high end RainBird controller. I've also seen, and used, small battery operated timers, complete with valve, that can control a single zone.

X. Use an anti-siphon device.

This is probably a law or something, but it's also a damn good idea. These little one way valves (a.k.a. vacumm breakers) keep crud from flowing back up your drip system into the water lines for your house.

Closing Comment

And once your drip system is installed, your neighbors will marvel at your thriving gardens and say:
Mistress Mary, quite contrary,
How does your garden grow?
With silver bells, and cockle shells,
And pretty maids all in a row.

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