Editing Drip irrigation (section)

==Components and operation==
[[File:dripirrigation.gif|thumb|Drip irrigation system layout and its parts]]
[[File:Subsurface drip emission on loamy soil.ogv|thumb|Water distribution in subsurface drip irrigation]]
[[File:Dianthus caryophyllus Colori Joy (p) 2005-12-04.JPG|thumb|Nursery flowers watered with drip irrigation in Israel]]
[[File:Drip emitter.jpg|thumb|Horticulture drip emitter in a pot]]
Components used in drip irrigation (listed in order from water source) include:
* Pump or pressurized water source
* [[Water filter]](s) or filtration systems: sand separator, Fertigation systems ([[Venturi injector]]) and chemigation equipment (optional)
* Backwash controller ([[backflow prevention device]])
* Pressure control valve ([[pressure regulator]])
* Distribution lines (main larger diameter pipe, maybe secondary smaller, pipe fittings)
* Hand-operated, electronic, or hydraulic control valves and safety valves
* Smaller diameter polyethylene tube (often called "laterals")
* Poly fittings and accessories (to make connections)
* Emitting devices at plants (emitter or dripper, micro spray head, inline dripper or inline drip tube)

In drip irrigation systems, pump and valves may be manually or automatically operated by a [[controller (irrigation)|controller]].

Most large drip irrigation systems employ some type of filter to prevent clogging of the small emitter flow path by small waterborne particles. New technologies are now{{When|date=February 2021}} being offered that minimize clogging.  Some residential systems are installed without additional filters since potable water is already filtered at the water treatment plant. Virtually all drip irrigation equipment manufacturers recommend that filters be employed and generally will not honor warranties unless this is done.  Last line filters just before the final delivery pipe are strongly recommended in addition to any other filtration system due to fine particle settlement and accidental insertion of particles in the intermediate lines.

Drip and subsurface drip irrigation is used almost exclusively when using recycled municipal wastewater.  Regulations typically do not permit spraying water through the air that has not been fully treated to potable water standards.

Because of the way the water is applied in a drip system, traditional surface applications of timed-release fertilizer are sometimes ineffective, so drip systems often mix liquid fertilizer with the irrigation water. This is called [[fertigation]]; fertigation and chemigation (application of pesticides and other chemicals to periodically clean out the system, such as [[chlorine]] or [[sulfuric acid]]) use chemical injectors such as [[diaphragm pump]]s, [[piston pump]]s, or [[aspirator (pump)|aspirators]].  The chemicals may be added constantly whenever the system is irrigating or at intervals.  Fertilizer savings of up to 95% are being reported from recent university field tests using drip fertigation and slow water delivery as compared to timed-release and irrigation by micro spray heads.

Properly designed, installed, and managed, drip irrigation may help achieve [[water conservation]] by reducing [[evaporation]] and [[Groundwater recharge|deep drainage]] when compared to other types of irrigation such as flood or overhead sprinklers since water can be more precisely applied to the plant roots. In addition, drip can eliminate many diseases that are spread through water contact with the foliage. Finally, in regions where water supplies are severely limited, there may be no actual water savings, but rather simply an increase in production while using the same amount of water as before.  In very [[desert|arid regions]] or on [[psamment|sandy soils]], the preferred method is to apply the irrigation water as slowly as possible.

[[Pulse drip irrigation|Pulsed irrigation]] is sometimes used to decrease the amount of water delivered to the plant at any one time, thus reducing runoff or deep percolation.  Pulsed systems are typically expensive and require extensive maintenance. Therefore, the latest efforts by emitter manufacturers are focused on developing new technologies that deliver irrigation water at ultra-low flow rates, i.e. less than {{convert|1.0|L|USpt imppt|abbr=in}} per hour. Slow-and-even delivery further improves water use efficiency without incurring the expense and complexity of pulsed delivery equipment.

An emitting pipe is a type of drip irrigation tubing with emitters pre-installed at the factory with specific distance and flow per hour as per crop distance.

An emitter restricts water flow passage through it, thus creating head loss required (to the extent of atmospheric pressure) to emit water in the form of droplets. This head loss is achieved by friction/turbulence within the emitter.