Nobody wants to knowingly waste water, but since over half of a typical household water use is outdoors, a poorly designed irrigation system is usually the cause. But it also stems from planting plants in the wrong locations. Most people don’t really monitor the operation of their drip irrigation system. Most of the time, they based its operation on whether their plants are doing well or not.
Here is a list of common practices that good landscape professionals adhere to. Reading through these may reveal some deficiencies with your own existing system. Not following these points can result in more costly repairs, inefficient irrigation, over watering and higher maintenance.
All irrigation systems must be equipped with a vacuum breaker as required by the Uniform Plumbing Code. These could be above ground atmospheric vacuum breakers that are built into the above ground valves, or it could be a pressure vacuum breaker which is installed before the valves which would then be underground located in a valve box. Above ground valves should not be used in climates where freezing is a concern and exposed PVC pipe is not a good idea either.
A shut off valve should be located along your mainline before the vacuum breaker so you can turn off the irrigation line for repairs while maintaining water for the main house.
Drip systems operate under low pressure, usually 20-30 psi. A pressure reducer is installed after the valve so the pressure going through the drip line and out the emitters is low enough so the fittings don’t blow off. Since there is no glue used as in PVC piping, drip fittings are designed for low pressure water delivery.
Lateral driplines should be placed in pipe sleeves when running under driveways, patios or other surfaces to access planting areas separated by hard surfaces or other hardscape like walls, planters, etc. This allows the piping to be installed in the first place without possibility of getting damaged or bent and allows the piping to be pulled out and replaced later if necessary.
Emitters for each plant should have a separate ¼” tubing connected to the lateral. Do not split off the ¼” tubing to feed more than one shrub since you will be diluting the amount of water than can reach the plant.
Keep the ¼” lines no more than 10 feet long measured from the lateral line. This may require the laterals to be looped or T-fittings inserted to provide relatively close distance to all the shrubs in any particular zone.
Adequately bury the lateral and ¼” tubing. The lateral line should be buried about 6-8″. If it is accidentally cut with a pick or shovel later on, it is easy to repair. Further, since the lateral is after the valve, they are not under pressure except for when the valve is running. ¼” tubing is often not buried deep enough often placed just underneath the gravel cover. ¼” tubing should be buried several inches in the soil so the lines will remain in place and not easily get pulled up from a rake and be exposed.
Avoid relying on hose bibs to locate your irrigation valves. Hose bib connections to a drip line may be manually controlled or you can install a battery operated single station valve. This is not a professional installation especially if the planting design requires multiple zones. For isolated areas cut off from connection to the main system, they can be used provided there is a nearby faucet.
Separate tree zones from shrub zones. This is a very common mistake. Trees ideally need water for a deeper watering (longer duration of watering time) and less frequently compared to shrubs which have more shallow roots.