Zoning Your Irrigation System
Many smaller residential drip irrigation systems do not require zoning, or dividing the system into two or more areas. Some medium and larger systems, however, would benefit by zoning in order to increase the system's overall efficiency, minimize water waste, and improve the health of the plants.
Zoning might be desired if you have plants with very different watering requirements. For example, you might want flowering plants, shrubs, and trees all on separate zones as the amount and the frequency of watering is quite different for each type of plant. If all of these types of plants were on the same zone, some plants would invariably be over-watered while some would be under-watered.
Zoning might be required if the number of plants and their cumulative watering needs would exceed the capacity of the water supply or irrigation tubing. For example, a water supply with a flow rate of 300 gallons per hour (gph) would not be able to sustain a single planting area requiring 400 gph, but it would be able to sustain two separate planting areas requiring 200 gph each if the two separate zones were watered at different times. Another example would be if a single planting area with tubing required a flow rate of 400 gph. That would exceed the maximum capacity of 200 gph for 1/2 tubing, so splitting into two zones would be necessary. With all the math floating around the process can seem very overwhelming but we have created a lot of reference material in our online classroom to help you. In addition our knowledgeable staff is always here to help you through any of your zoning questions.
Zoning can be accomplished by several methods. One common configuration is to use a faucet splitter and create two zones, while a more complex option involves PVC piping, with the water supply pipe connected to a manifold consisting of two or more electronic valves which then direct the water to different planting areas. Modular multi-zone manifolds are also available which can be adapted to connect to standard hose bibs and standard irrigation tubing. Some battery-operated water timers are designed for two zone operation. These timers can be connected to a single hose bib, and have two separate water outlets with separate timer options. An innovative product which has recently become available consists of a compact valve box which allows a single water inlet connection and four zone outlets controlled by separate compact electronic valves.
If your planting area consists of plants with different watering needs and zoning is not an option for any reason, you can still vary the amounts of water each plant gets by varying the number and types of emitters at each plant. Adjustable flow rate drippers can give you that variability, but it is sometimes quite difficult to balance the output on adjustable drippers if you have more than one adjustable dripper on the zone. You can also vary the drippers in your planting area by the drippers individual flow rating. For example, if you have two plants and the second plant needs twice as much water as the first, you can install a 1 gallon per hour (gph) dripper on the first plant, and a 2 gph dripper on the second. If you only have drippers with the same flow rating, you can install twice as may drippers on the plant that needs twice as much water.
Being able to zone your planting area and vary the drippers and/or drip rates at individual plants will give you the ability to very precisely control the water usage. You'll be able to give all your plants just the right amounts of water. An efficient, correctly-zoned and well-balanced drip irrigation system will inevitably result in less water waste, more cost savings and healthier plants.