Credit: Drip Irrigation by USDA (CC by 2.0)
by Rex Morris, El Paso Master Gardener
Drip irrigation puts water where your plants are and allows you to control water volume at a rate slow enough for the water to soak into the soil and not over- or under- water. It also allows timed watering during the coolest part of the day.
Step One. Tap into your main waterline or into an existing outside faucet. In either case, install an anti-siphon/backflow prevention valve to prevent the possibility of contaminated water backing up into your drinking water line. You can put a pipe tee on the anti-siphon valve. Attach a new hose bib to one end of the tee. Attach a PVC connector to the other side for the irrigation water.
Step Two (Install the irrigation valves). Now that you have a PVC tap off the water line, bring the water line down, and use PVC tees to tap off this water line to create as many zones as necessary to water all of your vegetation. If you try to water all of your vegetation off one line, the water pressure would likely drop too low in some areas to be effective. Create multiple zones and use a timer to turn on the water at each zone, one at a time, to insure adequate water pressure. It is a good idea to install an on/off valve at each zone prior to installing an irrigation valve. If something breaks in one zone, you can repair that zone while the others continue to operate. Select an irrigation timer (controller) that controls as many zones as you have. Run irrigation wiring from the controller to each of the irrigation valves.
Step Three (Running PVC pipe to each zone). Run PVC pipe below ground from each irrigation valve to its zone. At each zone, bring the PVC pipe up to just above ground and attach a polypipe adapter.
Step Four (Attaching polypipe). Polypipe is flexible black plastic tubing sold in lengths up to 500 feet. Attach the polypipe to the adapter, unroll the polypipe to the end of the zone, cut off the excess, and plug the end of the polypipe. Punch a hole into the polypipe near each plant and insert a drip emitter. If the drip emitter is not next to the plant, attach a ¼ inch tube to the end of the emitter and run the ¼ inch tube to the plant. Cover the polypipe, emitters and ground with mulch.
Your drip irrigation system will make your watering efficient and effective for your plants.
Related information:
“Good to Grow” Radio Show: Irrigation, Part 1 
“Good to Grow” Radio Show: Irrigation, Part 2
Efficient Use of Water in the Garden and Landscape
Low-Volume Irrigation-Design and Installation Guide