Anatomy of a Drip Irrigation System
A drip irrigation system or drip watering system is used for slow, controlled garden watering. It is not the same as a permanently installed underground sprinkling system such as is used for lawns. The drip system is a simple configuration that uses flexible plastic tubing and easy-to-connect sprayers and control devices. You can design a system to accommodate any kind of garden or landscaping and install it yourself. And you can afford it: A modest home system will cost about $150, including a timer.
Drip System Basics
A Y-fitting screwed onto your outdoor hose faucet lets you connect both a hose and the main line of the drip watering system: a length of 1/2-inch diameter plastic tube. This carries water to the garden, where 1/4-inch diameter branch lines distribute the water to various emitters such as spray heads. The plastic tubing is flexible, so you can run it anywhere you want, and it is black, so it virtually disappears from view as it lies on the soil. You do not bury it. That not only saves work, but lets you reconfigure the system without difficulty.
At the beginning of the main line, you can install a battery-operated timer that you can program to turn the water on and off. The timer is optional – you could just turn the water on and off manually – but it is what makes the system automatic, so you don’t even have to be at home to sit and relax while your garden waters itself.
A filter is installed after the timer to help keep the water emitters downstream in the system clean. This is an important component; don’t leave it out.
If your household water system has high pressure (55 psi or higher; ask your plumber or utility company) you should include a pressure regulator at this point in the main line. Excessive pressure might force fittings to come apart in the system. Also, many plumbing codes require a backflow preventer at the beginning of the line, so that water cannot be siphoned back into the household water system. It’s a good thing to have, even if your local code does not call for it. Both of these devices are inexpensive.
Different Types of Water Emitters
Three kinds of water emitters are shown in the diagram at left. Mini-sprayers, or mini-sprinklers, are just what you need to water grouped plants like perennial flowers or ground cover plantings. These sprayers can be mounted at any required height on plastic stakes. “Dial-a-Flow” emitters are adjustable to many flow settings so you can tune them to the plants’ needs. Flowers and shrubs require a greater or more diverse flow than others. Like mini-sprayers, these emitters mount on plastic stakes that you shove into the ground. There are dozens of other special-purpose emitters also available, but these two and a drip hose will handle most home gardening needs.
A drip hose has small emitters built into it. It is smaller – 1/4-inch diameter – than ordinary fabric soaker hoses, and does not spray the water out as a perforated sprinkler hose does. It is far more efficient than either of those hoses and is especially good for watering trees, hedges, and rows of vegetables.