- Drip Irrigation - Glossary of Terms

Branch line Polyethylene tubing that attaches to the mainline to bring water to a plant or to an area of a zone. Branch tubing is generally 1/4" or 1/2" tubing.

Elevation Variations in elevation can cause a change in water pressure within the system. Pressure changes by 1 pound for every 2.3 feet of change in elevation, or roughly 4 pounds of pressure for every 10 feet of change in vertical elevation. If you lose too much pressure, then the emitters at the end of the line may put out little, if any, water. If your water source is much higher than your garden, then you may need to use one or more pressure regulators to bring the pressure down to a level that drip prefers.

Emitter An emitter, also called a dripper, is a product used in drip irrigation to regulate the flow from the mainline or branch line tubing to the area to be irrigated. Emitters can be placed in the mainline or branch line, at the end of 1/4" branch line or pre-installed inside emitter tubing.

Filter A filter is used to remove particles from the water that might otherwise plug up your emitters. The size of the filter screen is expressed as mesh, with larger numbers denoting smaller openings in the screen. In drip irrigation, 155 and 200 mesh are common sizes.

Fitting A part such as an elbow, tee, hose beginning, hose end, coupler or other piece used to connect tubing.

(GPH or GPM)

See video showing how to determine flow
The amount of water available for the system. It is expressed as either GPH (gallons per hour) or GPM (gallons per minute). The products on our site have the water used stated in one of these units.
Flow is measured by timing how long it takes to fill a container of a given size with the faucet opened up all the way. To calculate the flow, you can either use our Flow Calculator or use the following formula:
  • Divide the size of the container (in gallons) by the number of seconds to fill the container.
  • Multiply that number by 3600.
  • Divide that number by 60 for GPM
Your flow will play a big part in determining how many plants (or how large an area) can be watered at one time. If your garden needs more water than the flow available, you can divide the drip system into as many zones (or hydro-zones) as necessary. A multi-zone timer will allow you to schedule each zone for a different start time and duration of watering.
Friction Loss As water moves through tubing, pressure is lost due to friction in the line. In tubing runs of more than 200 feet there can be a significant drop in pressure that can lower the output of some (non-pressure compensating) emitters or sprayers at the end of the line. Friction loss can increase if the tubing goes up hill or decrease if it goes down hill. To decrease friction, a larger size of tubing can be used.

Hydro-zone A hydro-zone describes a group of plants that need watering at a similar frequency. For example, if you have shrubs and trees you may want to water the shrubs every other day and the trees once every two weeks. This would not be possible within a single hydro-zone. Establishing two hydro-zones, one for the trees and one for the shrubs would allow you to water the two groups to their individual needs. Within a hydro-zone if one plant needs more water than another it can be given an additional emitter or an emitter with a larger flow.

Mainline Polyethylene tubing used to cary the water from your water supply to your system. There are 2 commonly used sizes: 1/2" and 3/4". 1/2" mainline tubing has a capacity of around 240 GPH. 3/4" mainline tubing has a capacity of around 480 GPH.

Manifold A collection of valves and associated parts used to distribute water to multiple zones.

Pressure (PSI) Pressure is the force pushing the water flow. Pressure is expressed in pounds per square inch or PSI. A pressure regulator can be used to reduce pressure to a range that works well with the particular products you are using. Most of our products operate best between 20 and 40 pounds of pressure. If your water pressure falls within this range you may not need a pressure regulator on your system. If you are using pressure compensating emitter tubing, emitters or sprayers, the range of pressure can usually be between 10 and 50 PSI and still provide an even watering to your garden.
If you have low pressure you may need to use non-pressure compensating emitters or other products which can operate with very little water pressure.

Describes an emitter or sprayer that delivers a consistent amount of water over a specified range of pressures. This is useful in situations where the tubing runs are long or the terrain the tubing runs over is hilly. Pressure compensating emitter tubing typically operates in the range of 10 to 50 PSI.

Soil With drip irrigation the density of the soil affects how far the water flows from the emitter. Light, sandy soils require a higher rate of water application. Heavy clay and clay loams often benefit from a lower water application rate
soil consistency
Heavy Clay Soil
Low flow emitters are recommended. If a high flow emitter is used, it may exceed the soil's ability to absorb water, resulting in runoff.
Medium Textured Soil
Requires closer emitter spacing (compared to clay soil). Medium flow emitters are recommended.
Light Textured Soil
Closer emitter spacing is required in order to uniformly wet the soil profile. High frequency irrigation can be used to achieve similar results.

Supply This is a non-standard use of the term but we use it to indicate how you connect to the water system. This is often a faucet, with standard hose threads or a PVC system with pipe from 1/2" to 2" or more and threading that may be male, female or slip (no threads).

Valve In drip irrigation there are two types of valves. Manual valves are used to offer great flexibility and control of your irrigation and can be used in place of automatic valves or in automated systems to shut off areas of your system from irrigation.
Automatic valves are used with an electric controller or within a battery timer to automate the watering with your system.

Water Pressure
Water pressure describes the force behind the water in a line and is expressed in Pounds per Square Inch (PSI). In drip systems, the pressure is commonly limited to 30 PSI with a pressure regulator. With non-pressure compensating emitters and sprayers, the higher the pressure the more water will be put out in a given period of time.

Water Source The water source is where the water comes from. This can be a municipal system, a well, a pond, an irrigation ditch, a barrel or wherever your water comes from. Usually City and Well water are easy to filter for drip irrigation systems. Pond, ditch and some well water have special filtering needs. The quality of the water source will dictate the type of filter necessary for your system. Sand, silt, minerals, organic matter and rust bacteria are specific concerns. In some cases magnetic water conditioning may be helpful.

Zone See Hydro-Zone above.