In this video, This Old House plumbing and heating contractor Richard Trethewey explains how to install a drip-irrigation system.
Installing drip-irrigation
- Dig series of trenches across yard to minimum of 4 inches deep; space the trenches about 12 inches apart.
- Run PVC pipe from water supply to trench.
- Fabricate two manifolds out of PVC pipes and fittings.
- Set the manifolds in trenches at opposite ends of yard.
- Attach one manifold to the water-supply line.
- Run series of polyethylene drip lines back and forth in across yard between the two mainfolds.
- Attach the drip lines to the manifolds.
- Test system for leaky fittings and to ensure the emitters are slowly dripping water.
- Backfill the trenches and plant grass seed or lay sod.
Pressure and Flow Check: Before connecting your system, verify your water pressure and flow rate at the hose bib. Drip lines need 25 to 30 pounds of pressure per square inch to ensure that the emitters can maintain a slow, measured release of water. Each watering zone should be controlled by a valve that has the added tasks of regulating water pressure and filtering out mineral deposits. Be sure to install a backflow prevention device to keep irrigation water from flowing back into your home’s water supply.
Pro Tip: Before digging any trenches, check with the local building department to obtain all necessary permits, and contact a one-call center to have the local utilities mark any buried electrical cables, gas lines, or water-supply pipes. Also, to prevent the water coming out of the drip-irrigation tubing from evaporating too quickly—and to help hide the tubing—cover the area with bark mulch spread at least 4 inches deep, which will also deter weeds from sprouting.
Key Detail: The drip system’s PVC supply lines should be set 8 to 12 inches below ground, while the perforated polyethylene drip hoses—typically ¼ to ½ inch in diameter—rest on the soil surface. Weave them between plants every 12 to 16 inches and cover with 2 or 3 inches of mulch, typically chipped bark. This prevents evaporation while allowing easy access for future maintenance.
Tools
You may want to rent a trencher to cut down on digging labor.
