How does drip irrigation work, and how long should I run it?
Short answer: A home drip system runs water through a backflow preventer, filter, and pressure regulator (about 20 psi) into tubing and emitters that usually deliver 0.5, 1, 2, or 4 gallons per hour. Water used = gph x hours x number of emitters. Twenty 1 gph emitters for 45 minutes use 15 gallons.
How much water does drip irrigation save?
Drip is a type of microirrigation. It is low pressure and low flow, and it puts water at the root zone. That cuts runoff and evaporation.
EPA WaterSense says microirrigation uses 20 to 50 percent less water than conventional sprinklers. EPA also says it can save a typical home more than 25,000 gallons a year when installed instead of a traditional system. Your savings depend on your yard, climate, and how you schedule it.
What parts does a drip system need?
University of Arizona Extension lists these core parts, in order from the faucet or valve:
| Part | What it does |
|---|---|
| Backflow preventer | Stops irrigation water from flowing back into drinking water. Arizona Extension says one is required on all irrigation systems; local codes regulate installation. |
| Filter | Screens out particles. Even small particles can plug emitter openings. |
| Pressure regulator | Drops household pressure (typically 50-75 psi) to about 20 psi for drip. |
| Timer or controller | Sets how often and how long the system runs. |
| Tubing and micro-tubing | Carries water along rows and to individual plants. |
| Emitters | Release water slowly, usually at 0.5, 1, 2, or 4 gallons per hour (gph). |
| Flush caps | Sit at the end of each line so you can open it and flush out debris. |
A common layout is backflow preventer first, then filter, then regulator, but follow your kit instructions. Check your local code for which backflow device is required.
How long should I run drip irrigation?
There is no single right run time. Arizona Extension says to adjust schedules for plant needs, weather, season, and soil texture. What you can calculate exactly is how much water you are applying.
Formula: gallons = emitter flow (gph) x hours run x number of emitters
Example: 20 emitters rated 1 gph, run for 45 minutes (0.75 hours):
20 x 1 x 0.75 = 15 gallons
Each plant with one 1 gph emitter gets 0.75 gallon in that run.
Gallons used by 10 emitters
| Emitter rating | 30 minutes | 1 hour |
|---|---|---|
| 0.5 gph | 2.5 gal | 5 gal |
| 1 gph | 5 gal | 10 gal |
| 2 gph | 10 gal | 20 gal |
| 4 gph | 20 gal | 40 gal |
To work backward, divide the gallons each plant needs by the emitter rate. A plant that needs 1 gallon on a 2 gph emitter needs 30 minutes.
How much a plant needs is the hard part. Sandy soil, hot weather, and bigger plants generally need more. Your local extension office can suggest amounts for your area and plants.
Why do drip emitters clog, and how do I flush the lines?
Particles in the water are the main cause. That is why the filter matters. Arizona Extension recommends:
- Keep the filter clean.
- Remove flush caps at the end of each line periodically and run water until debris clears.
- Inspect emitters and lines monthly to confirm water is coming out.
A rule of thumb: flush new lines before installing emitters, and flush again after any repair. Dirt gets in whenever the tubing is open.
How do I winterize drip lines?
Arizona Extension notes that winterizing may be needed in cold areas to prevent freeze damage. Oklahoma State Extension gives these steps:
- Shut off the water, then turn off the timer.
- Drain backflow preventers and pipes exposed to freezing temperatures. Wrap them with insulation if possible.
- Drain drip tape and soaker hoses, and store them out of sunlight.
- If a hose has already frozen, leave it in place until it thaws. Moving it frozen can damage it.
Oklahoma State advises leaving compressed-air blowouts to a professional. Done wrong, the pressure can damage the system.
Many people also open the flush caps so the lines drain. Bringing the filter and regulator indoors is a common practice, but check your parts’ instructions. For the faucet the system connects to, see how to winterize an outdoor faucet.
Quick answers
What psi does drip irrigation need? University of Arizona Extension says drip systems need about 20 psi. Household supply is often 50-75 psi, so you need a pressure regulator.
Do I need a backflow preventer for drip irrigation? Yes. It keeps irrigation water out of your drinking water. Local codes regulate the type and installation.
How many gallons does a 1 gph emitter use? One gallon per hour of run time. Ten of them for 30 minutes use 5 gallons.
Does drip irrigation save water? EPA WaterSense says microirrigation uses 20 to 50 percent less water than conventional sprinklers.
How often should I flush drip lines? Arizona Extension says to flush periodically and inspect emitters monthly. Flush sooner if you see weak or uneven flow.