Drip Irrigation—Installation and Maintenance
by SCMG Steven Hightower
Drip irrigation is both simple and complex at the same time. You can either install drip yourself, or turn to a professional. Drip irrigation is relatively easy to install in general for simpler home systems. It goes together much like a tubular erector set—all snapping together. Main 1/2 inch lines slip into fittings on the automatic valves; 1/4" feeder tubes slip onto barbed fittings that poke into the main lines; "tee" and "el" fittings allow feeder branches to go to individual plants; continuous emitter tubes snap/poke in like feeder tube then snake through areas of denser planting.
It gets a bit more complicated to determine the proper controller (number of stations is dictated by the amount of landscaping, and number of different zones which need different amounts and times of water), determine whether pressure reducers are necessary (length of main line runs; uphill or downhill), whether filters should be installed (well water: yes; city water: maybe).
If you have the system professionally installed by a reputable professional gardener or irrigation firm, everything will be done properly, but it will be substantially more expensive than doing it yourself.
If you are generally handy, advice from representatives at outlets which sell drip equipment, ranging from Friedman's to Home Depot to your local hardware store to specialist firms such as Harmony Farms and Wyatt Irrigation Supplies can assist you, and make a DIY job feasible. Also, an excellent primer is Drip Irrigation in the Home Landscape, available from the University of California Agriculture and Natural Resources. Drip Irrigation for Every Landscape and all Climates by Sonoma County author Robert Kourik is a great resource.
You must visually monitor the system regularly. Lines break, tube pulls away from fittings, shovels make unknown cuts, dogs chew, emitters plug. Look and listen for geysers, spouts, leaks, large wet areas, etc. Also monitor the health of your plants for signs of too little or too much water. Check the soil periodically for correct moisture. A simple moisture probe—6” metal spike connected by a wire to a moisture meter—is a great investment. You also need to learn basic repairs and keep a toolbox of useful repair parts and tools: wire cutting pliers, regular pliers, hole punch, sturdy scissors, various connectors, sprayer heads, emitters, bubblers, emitter tubing, goof plugs, etc.
Monitor the system from the plants’ perspective. Native and drought-tolerant plants need water for 1-2 years to become well established. After that, they may need only occasional water in summer.
Over time, you will need to adjust your system, to reduce water to some plants, and increase it to others. Gardens are constantly changing: plants die and must be replaced; new sections are added; plants grow, and need more water. The drip irrigation system has to change as well, in order to maintain maximum efficiency in the use of water. Indeed, this flexibility is one of drip’s great advantages over overhead, fixed risers, which, once installed, cannot readily be moved.
Schedule a maintenance review when the system is first turned on in the spring and before you turn it off in winter. Annually, the system should be flushed, by uncapping the main lines, and running each station for a few minutes. Also, each emitter or bubbler or sprayer needs to be checked, and may need to be taken apart and cleaned (or, with the relatively low cost of individual items, simply replaced). Filters, if you install them, should be cleaned every couple of months, depending on the amount of debris in the water. During the growing season, periodically check and clean (or replace) emitters. Flush the system thoroughly after any main line break to avoid emitter clogging. Clean filters more often if using well or pond water and less often if using city water. If the system does not appear to be working, the first thing to check is the filter!
Modern controllers contain the seasonal adjustment feature to allow the adjustment of the overall system from "normal" by percentages up and down. This is very useful because when you turn the system on in the spring, you can run this override down to, say, 50% for the first month, increase to 70, then 90, and finally 100% in the heat of the summer. Further, during really hot spells, you can run it up to, say, 130% and avoid having to increase the watering individually on all the stations.
Above all—watch your plants. If something’s wrong, they will tell you.
©Sonoma County Master Gardeners