Glossary of Terms Common in Drip Irrigation 

Adapter – A fitting to connect tubing or other fittings with different thread types or sizes to each other.   

Atmospheric Vacuum Breaker – A type of backflow prevention device installed above the highest point in an irrigation system. This prevents backflow to the water source. These breakers resemble a 90-degree elbow with a hood on top and allow air into the system if a vacuum or siphon condition arises. An AVB contains a poppet valve that is held closed by water pressure and will drop open when the upstream pressure drops to atmospheric pressure or below allowing the air to enter breaking any siphoning or vacuum condition. Atmospheric vacuum breakers work best when installed at least 6 inches above the highest pipe in an irrigation system.

Backflow – When water flows back from an irrigation system toward and into the main water system. This is caused by back siphon or backpressure in the lines. It is important to stop backflow from occurring due to the possibility that dangerous chemicals, fertilizers, bacteria, animal waste, pesticides or insects, could enter an irrigation system.  All could pollute household water.

Backpressure – Pressure toward the water source. This can occur when tubing or pipe is elevated above the water source.  Another cause of back pressure is when a sudden loss of pressure occurs. This could be caused by a break in the supply line.

Backflow Preventer – Installed correctly, this will stop backpressure or backflow from affecting the original water supply in the house. Since water in an irrigation system can be tainted with fertilizers, bacteria or animal waste, among other harmful things, it is vital that they not be allowed to backflow into the home water.

Ball Valve – This simple manual on/off valve has an internal ball with a hole through it. The hole in the ball aligns with the flow path when the valve is open, allowing it to pass through easily. The hole rotates and stops the flow of water when you close the valve. 

Barbed Fitting – A type of irrigation fitting — drip coupling, tee, elbow or emitter — that has a barbed end with ridges that hold it securely in place in the poly tubing. These barbs can be used to attach directly to holes that were punched into drip mainline tubing. Also called insert fittings.

Brackish Water – Has a salt content percentage somewhere between sea water and fresh water.

Bug Plug – This small bug or insect plug stops insects from crawling into ¼” tubing and clogging it up. It does not stop water from flowing out through the tubing.

Check Valve – These one-way valves let water flow down a tube or pipe in only one direction.  They have a spring that requires sufficient water pressure to open and begin the flow through the valve. These are commonly used in irrigation systems, sprinklers and sump pump piping. Check valves prevent water flow from reversing toward the source.

Compression Fitting – No adhesive is required to use a compression fitting between pieces of poly tubing. Like sized tubing is simply pushed inside these fittings on all sides.

Controller – An irrigation system controller regulates when the electric valves in the system open and close. They can also be called a timer as they can be set up on a schedule to deliver just the right amount of water to the lawn or garden at particular days and times. Controllers send low-voltage electric impulses to the valve to open or close it.

Coupler or Coupling  These tubing connectors are available in barbed, compression or Perma-Loc. Commonly, a coupler attaches two sections of like-sized tubing to one another. Some connect different types of pipe or tubing in a process called adapting.

Cross – As the name suggests, this is a tubing fitting that forms a cross shape. It is used to connect four pieces of tubing together. They can be Perma-Loc, barbed or compression in type.

Diameter – Width across the round opening of tubing. Inside diameter (ID) and outside diameter (OD) are both used to find the measurement of tubing. It is vital to know what your tubing diameters are so you can choose the correct fittings to match your tubing.

Diameter of Throw – Diameter of the zone watered by a 360 degree sprinkler when operated in a wind-free environment.

Drip Irrigation – Also known as micro irrigation, this type of watering system brings water to the plant roots in a slow trickle or flow. Sprinkler systems spray water through the air so it lands on plant leaves, which results in loss of water due to evaporation. Drip irrigation conserves water and gets it where the plant needs it most.

Drip Systems – Economical watering systems prevent evaporation and runoff because the water is delivered directly to plant root areas. Drip systems make watering potted plants, raised gardens and vegetable patches must easier.  Drip Systems are also not affected by wind.

Drip Tape – This flat drip tubing expands when water flows through it. Drip tape allows water to slowly seep out through emitters that are embedded into the tape at preset spacings. It is often used by commercial farmers or homeowners who have plants growing in straight rows.

Drip Tubing – Also known as poly tubing or pipe - polyethylene tubing is commonly black and flexible enough to make “S” shapes during installation. It is commonly used as the main supply line in a drip irrigation system. Roll lengths vary by size of tubing purchased.  Commonly 1/8” and 1/4” sizes are referred to as micro tubing.  Whereas, 1/2”, 3/4” and 1” are referred to as mainline tubing.

Dripper  This mechanism is also commonly called an emitter or drip emitter. All names are interchangeable.  Drippers are attached to an irrigation system to drip water at a particular rate near a plant. They can come in many different styles and rates of flow, depending on the application. Both barbed ends, which are pushed into tubing, and threaded bases, which are screwed into PVC or risers, are commonly used.

Drip Emitter Tubing – Available in both ½” and ¼” sizes, this irrigation tubing already has emitters inserted in at preset spacings that range from 6 inches up to 24 inches.

Dynamic Water Pressure – This is also called working or operating pressure and is the water pressure that is measured in an operating drip irrigation system. In a drip system, a pressure gauge can be used to check your system's dynamic water pressure.

Elbow – An elbow makes a 90-degree turn in drip tubing. Elbows are sometimes called 90s as well. We sell Perma-Loc, barbed and compression elbow fittings.

Elevation – The elevation of the ground must be considered carefully when planning a drip irrigation system. Elevation causes changes in water pressure, which may have to be compensated for with valves and pressure compensating emitters. These emitters put out the same flow regardless of fluctuations in pressure. Drip irrigation systems are easily affected by elevation changes because they operate at low pressures. Water pressure is measured in PSI (pounds per square inch).

Water Pressure changes .433 pounds per foot of elevation change.


  1. For every 2.3 foot of rise in elevation, water pressure raises by 1 pound.
  2. For every 10 foot drop in elevation, it decreases 4 pounds.

Emitter Tubing – This is also called dripline and comes with emitters already embedded into the tubing at specific lengths along the tube: ranging from 6 to 24 inches apart. This convenient tubing is most often used to water short straight rows of plants, create tree rings or weaved in an “S” pattern to cover densely planted landscapes. It comes in either ½” or ¼” sizes.

Evaporation – Natural change from liquid water to water vapor. Increases at higher temperatures. 

Evapotranspiration – (ET) These rates are calculated based on a particular plant type’s transpiration and evaporation rates. It is a measure of how quickly water changes to vapor and is lost in the air. It is used to determine appropriate watering schedules for particular crops.

Female Adapter – An adapter with internal threads to be used to connect fittings with dissimilar sizes, thread types or connection type.

Female Hose Thread FHT stands for Female Hose Threads.

Fertigation  Plant fertilizer is applied using the drip irrigation system to deliver it directly to the plants' root zones.  It makes fertilizing vegetable gardens or row crops very easy. Injecting the fertilizer into the drip irrigation system allows it to mix with the water evenly and be delivered in just the right amounts. Typically, plants are fertilized throughout their growing cycle, with the largest doses of fertilizer being applied as plants begin to bear fruit.

Filter  Screens in filters exclude larger particles from entering the drip irrigation tubing. Filters are invaluable if you want to prevent clogging of drip emitters. Screen mesh comes in 150 or 200 mesh varieties, with the 200 mesh having the smallest openings in the screen. 200 mesh is commonly used for misters or foggers, which require a fine spray.

Fittings – Are used to connect sections of drip irrigation tubing and PVC pipe. Fittings come in a wide variety of styles, materials and sizes: tees, elbows, couplers, male and female adapters, swivels, valves, bushings and reducers, just to name a few. The connection type of a fitting may have threads, barbs, or be compression style, Perma-Loc or slip.

Flow Control Valve – These valves are inserted into a section of tubing so that a particular section or zone can be turned off if necessary. A great use for these valves in a Drip irrigation system is when watering multiple vegetable or flower beds. When a specific bed does not need water, the flow control valve can easily be closed.  However, the rest of the beds continue to receive water.

FPT Female Pipe Thread. The threads are located inside the connection point.

Goof Plug – When installing a drip irrigation system, one should have a few goof plugs, or mistake plugs on hand. They come in handy to plug up the ends of ¼” tubing or to plug holes in mainline tubing.

GPH  Gallons per hour.

GPM Gallons per minute.

Gravity Drip Irrigation – This drip irrigation system type relies on the natural force of gravity to move water through the system. Water is held in an elevated reservoir and flows in a controlled manner through the tubing to water the plants. This creates a lower-pressure system than when hooking up to a faucet, so using non-pressure compensating emitters and drip tape is ideal for this application.

Gray Water – Any used water coming from household sinks, showers, tubs, dishwashers and washing machines is called gray water. It is occasionally recycled for use in irrigation systems when people want to be more environmentally friendly. Gray water does not contain sewage.

Hole Punch – Tool used to form holes in solid tubing to insert drip emitters or fittings.

Hose Bib – Another name for any faucet or spigot that is the attachment point for a drip irrigation system.  For many homeowners, this is where their drip irrigation system will begin. This is a manual valve that has a male attachment end, which is usually used for garden hoses.

Hose Thread – The official name for this is “garden hose thread” or GHT and varies from pipe threads. Hose and pipe threads are incompatible and should never be attached to one another.  Hose threads are found on garden hoses and many different irrigation fittings. Male threads are on the external surface of the fitting while female ones are found inside the fittings. These GHTs do not require Teflon tape in order to create a water-tight bond.  Only a hose washer is needed.  If  you notice leaking from the fitting: (1) check to see if a washer is present  and (2) check to see if the washer is worn out.  A hose washer can be replaced if worn.

ID Abbreviation for inside diameter of tubing.

Inline Emitter  Two main varieties of inline emitters or inline drippers exist for use in drip irrigation systems. (1) Emitters are embedded into drip tubing or tape while manufacturing it, resulting in drip line or drip tape. (2) The other type of inline emitter has barbed ends on two sides and can be attached to solid poly tubing to create custom drip line.

Injectors  Used in the fertigation process, they inject fertilizers or nutrients into a drip irrigation system and then deliver it directly to the plants' root systems. This makes fertilizing plants a breeze. 

Laser Drilled Tubing  Micro tubing with evenly spaced holes drilled by a laser. Drip line tubing is more precise due to actual emitters being embedded into the tubing during extrusion. 

Lateral Line – This is any hose or pipe that runs away from the main supply line in a drip irrigation system. The lateral line branches out to carry water to a particular water zone that is to be distributed by drip tubing, emitters or sprinkler attachments.

LCD Liquid Crystal Display is frequently used in drip irrigation hose end timers and controllers.

Mainline – This is the main tubing or pipe that carries water from the water source throughout the drip irrigation system. In high pressure irrigation systems, this is usually PVC pipe. In drip irrigation systems, ½” , ¾” or 1” tubing is commonly called the mainline.

Manifold Irrigation valves arranged in a valve box that control water flow to multiple zones. 

Maximum Flow Capacity – The largest volume and pressure of water that is available at your area to install drip irrigation. When designing a drip irrigation system, this flow capacity is important because it lets you know how many drip emitters can work at any given time.

MHT – Male Hose Thread.

Microspray  This term describes multiple types of small sprayers specifically created for use with drip irrigation setups that are usually used for landscape and flower garden applications. Spray jets in combination with a base will water a larger zone than other watering methods. 

Microsprinkler or Rotary Micro Sprayer or Spinners  These micro spray emitters rotate to cover a watering zone up to 15 feet. They can be inserted directly into drip irrigation tubing and operate optimally at a water pressure of 25 psi. 

Micro tubing  Also called spaghetti tubing. This small, flexible tubing is ¼” in diameter and is used extensively as a lateral line from ½” or larger mainline tubing. Micro tubing is often used with drippers, misters or sprayers and comes in flexible vinyl and polyethylene. 

Misting – A process of using drip irrigation coupled with mist or fog attachments to create a thin spray over an area. Higher water pressures are recommended (40+ PSI) to create very fine water drops. 

MPT – Male Pipe Thread. The threads are located on the outside of the pipe or fitting.

Multi-Outlet Emitters  Often added to existing sprinkler systems in a process call “retrofitting".  This involves running 1/4” micro tubing from emitter outlets directly to each plant.

Non Pressure Compensating Emitters  Water output changes based on water pressure and elevation of the drip irrigation tubing. Non pressure compensating emitters function best on level areas and can be used in gravity applications. They do not compensate for changes in water pressure, so a steady pressure is best.

OD – Abbreviation for "outside diameter" of drip irrigation tubing. 

Pipe Thread National Pipe Thread (NPT) can be referred to as pipe thread. Pipe threads should not be matched with hose threads as they differ greatly. Use Teflon tape to create tight seal between pipe threaded fittings.  

Poly Tubing Another name for drip irrigation tubing.

Pressure  When used specifically with drip irrigation systems, pressure refers to how much force the water creates moving through the main line tubing. Pressure is measured in PSI and must be sufficient to move the water properly through all tubing, valves and fittings. 

Pressure Compensating Emitters  When water pressure changes randomly, these emitters regulate it so a consistent output is maintained at each dripper.

PSI  Pounds per square inch.  Used to measure water pressure. 

PT  Pipe thread.

PVC A common form of plastic used for pipes and fittings. PVC is most commonly used for underground transport of water since sun exposure can weaken it. Purple PVC pipe means gray water is being transported. Gray PVC pipe indicates “Schedule 80,” which is a measurement of thickness.

Radius of Throw The radius is the measurement from the watering devices head to the farthest distance that the water sprays. This term can be found under the specifications tab for different types of spray heads and emitters that create a circle of spray around them. 

Rain Sensor A sensor that can tell whether it is raining or not. If rain is sensed, then it will send a signal to the drip irrigation system hose end timer or controller to keep it from turning on, thus saving water.  

Reducer This fitting is used to allow two different-sized sections of tubing to join together. We sell reducers that join 1/2” and 3/4” tubing.

Root Zone This is the area in which a particular tree or plant’s roots live underground. An irrigation system should accommodate the overall root zone of the plants that are being watered with it. The water must be spread enough and run long enough to penetrate the soil to get to the roots for the tree or plant to grow. Things such as soil type, plant species and how compact the dirt is all affect the size of the root zone. 

Run Time How long a drip irrigation system or single zone for watering runs. A timer can be used to control the time frame.    

Shrub Adapter This type of drip irrigation adapter should be attached to a ½” riser.  The other side of the adapter accepts any spray jet or threaded watering device with 10/32 threads.  

Shut-Off Valve The valve, usually manual, that shuts the water off to the entire section of a drip irrigation system or watering zone.

Solenoid A 24-volt electromagnetic device that is attached to and controlled by an irrigation controller. They are responsible for opening and closing valves at the right time. 

Staked Emitters – Emitter affixed to a spike. Great for potted plants.

Subsurface Drip Irrigation  Subsurface refers to installing drip irrigation tubing underground so that water flows out directly to the plant roots. This can be economical and prevent evaporation water loss.  One word of caution when burying tubing, rodents love to chew on drip tubing.  If they chew through the tubing, it is hard to spot leaks and holes when its completely buried underground.

Swivel An adapter with a female hose threaded connection point that swivels for easy connection. Use a washer to create a seal that will not leak water while the drip irrigation system is in use.

Spinner These micro sprinklers spread water in large drops over an area up to 15 feet in diameter.

Tee Any fitting in a "T" shape used to form a three-way juncture between the sections of like drip irrigation tubing.

Trickle Irrigation  Same as drip irrigation.

VAC Volts Alternating Current. 24 VAC is the standard operating power for the majority of irrigation controllers and electronically operated valves. 

Valve The part of a drip irrigation system that can move either manually or electronically to control water flow in the system.

Velocity The speed of water as it flows through drip irrigation tubing or PVC pipe. Usually measured in feet per second (ft/s).

Volume The total volume of water that travels through any irrigation tubing or pipe.  Volume is often referred to as flow rate, which can be listed in: GPM (gallons per minute), GPH (gallons per hour), ft3/s (cubic feet per second), m3/h (cubic meters per hour), L/M (liters per minute) or l/s (liters per second). 

Water Source City water, well water, lake, irrigation ditch, pond, water barrel or tank are examples of a water source that can be connected to a drip irrigation system.

Winterization Preparing an irrigation system for the winter so that tubing, drippers, micro sprinklers, timers and other parts are not damaged by freezing water. Winterization involves removing all water from the system so it cannot freeze and expand. 

Xeriscaping Using local plants that resist drought to design a yard and garden to minimize the necessity of frequent watering. 

Zone  A watering zone is a general area of a garden or landscape that is serviced by a single drip irrigation system. Zones should be planned carefully prior to installation so plants with similar watering needs are in the same zone. Things to take into account are the types of plants, sidewalks or patios in the area, amount of sun, shade and wind.  Multiple zones may be needed if the water requirements of a landscape, garden or other areas surpass the capacity that a single drip irrigation system can provide.  For example, if your area to be watered requires more than 200 gallons per hour, then two or more zones using 1/2” tubing would be needed.  As 1/2” tubing can only provide up to 200 GPH per zone.