The drip system has long been touted as one of the most efficient garden irrigation systems. In general, a drip system lets the water seep through the soil to the roots of the plant in a localized fashion. It is the best and most practical way to water garden plants, shrubs, and even trees in most areas. With a drip system, water flows through flexible tubing and delivers water directly where it is needed most — over the roots of a plant. The flow of water can even be adjusted to meet the watering requirements for each kind of plant.
The parts that connect the source of the water to the drip system are called the head assembly. The head assembly includes a timer or a manual control valve, a backflow preventer, a filter, and a pressure regulator. Each component has a distinct function to ensure that the drip system works perfectly.
The control valves turns the water off and on. For gardeners with a single drip line that is attached to an outdoor faucet, the faucet, itself, is the control valve. However, if the drip line is attached to a timer, the control valve is part of the timer. Oftentimes, the drip line is attached to the water line, then, a separate control valve is required for each drip line circuit.
A backflow preventer keeps the water from flowing back into the water supply, thereby keeping the water supply clean and a filter prevents clogging. Some filters come with a fertilizer injector. The fertilizer injector lets fertilizer be added directly to the water for the plant. The pressure regulator lets the gardener lower (or raise) the water pressure so that the water does not flow from the drip system too forcefully (or weakly).
Tubing and fittings carry water from the head assembly to the various sections of the garden. Drip tubing is usually constructed of black polyethylene and is very flexible. The flexibility of the tubing lets it become woven through plants and wrapped around shrubs and trees. Smaller microtubing can be linked to the drip tubing and can be branched out in other directions. Stakes are the best ways to firmly hold microtubing into place.
Most drip systems dispense anywhere from less than one to over two gallons (3.8 – 7.5 liters) of water per hour through the drip emitter. It is essential to consider the soil and the plants of the garden to determine which water output rate is best. The goal is to wet 60 percent of the root zone. Water flows downward in sandy soil, but it spreads wider before it flows deep in clay soils. If the garden is on a slope, more water emitters may be needed with a lower amount of water output.
Generally, vegetables should have the least number of water emitters with the lowest rate of water output – less than one gallon (3.8 l) per hour is ideal. Other plants, such as flowers, ground covers, and small shrubs and trees can also thrive with only one water emitter, but they should have at least one gallon (3.8 l) per hour of water. Larger shrubs and trees may need two, three, or four emitters — depending on the size of the tree — and can receive two gallons (7.5 l) of water per hour.