Drip irrigation is a highly efficient and effective way of irrigating. Due to its design, there is very little water waste, including almost no water run-off or evaporation. With drip irrigation, water is applied on a slow, even basis right at the root level of the plants. In effect, the water is "dripping" onto the roots, as implied in the name of this type of irrigation. This type of irrigation has the added benefit of keeping the water off the leaves, stems and flowers. Water left to sit on these parts of plants can contribute to disease and to mildew and mold growth.
Drip irrigation systems are composed of plastic pipes that are buried, on average, a few inches under the surface, depending on the crop. The pipes can be round or "tape" (flat, flexible) pipes, or a combination of both types. Some drip irrigation systems lay on the surface of the ground. The pipes have openings a minimum of 18 inches apart, called "emitters," which allow water and fertilizers to leave the pipe and seep into the soil. The simplest systems contain a control valve, a valve to prevent backflow, water pressure regulator, filters, the tubing and end caps. More complicated systems include chemical injection points, which allow for the injection of fertilizers to aid the crops and chlorine to keep the water clear, timers to control when the water is released, and air vents to equalize air pressure so that soil is not sucked into the emitters when the water is turned off.
While drip irrigation systems are less wasteful of water than traditional above-ground systems, they are also more expensive on average to install. In addition, blocked tubes and emitters are a real problem. Most systems have filters set up to filter the water so that sediments and minerals will not clog the pipes from the inside, but this does not help keep the emitters clean. It is very easy for soil, pebbles and even insects to clog the emitters from the outside. Another common problem is leaks in the pipes. These can be caused by farming tools or even animals. A leak will cause uneven irrigation and water waste. For these reasons, drip irrigation systems must be closely monitored and carefully maintained. Flushing the tubes once a month is recommended, as is a visual inspection of any above-ground tubes or tapes.