Designing a Drip Irrigation System
Although I have the advantage of having a sprinkler system for our lawns and ornamental gardens, this approach does not work well for either a vegetable garden or planters. In the vegetable garden an overhead sprinkler system uses more water than is necessary. In addition, wetting the leaves can lead to more diseases and other plant damage that will ultimately lower your crop yields. For planters, overhead sprinklers do not to an adequate job since the water typically does not penetrate the foliage and reach the soil in the planter.
My solution to both these issues was to use a drip irrigation system. A drip irrigation system not only saves water it is easy to install, easy to use, easy to design and redesign when necessary and can be relatively low cost.
Drip irrigation works by providing a slow trickle of water directly to the soil. This results in significant water savings since the water soaks into the soil rather than evaporates in the air and since water is applied only where needed, directly at your plants roots.
The first part of your drip irrigation system is connecting the system to the water source. For this you need 6 basic components:
Faucet or Valve Tap -- this is your water source whether from your outdoor tap or a rain barrel.
Pressure Regulator -- most systems (particularly those of your home outdoor tap) will need a pressure regulator to reduce the pressure to the smaller drip lines you will be installing.
Backflow Preventor -- you need this to prevent water from flowing back into you home water system when the system is turned off. In many municipalities it is the law to have a backflow preventor on drip irrigation systems but it is just wise to do so no matter what.
Filter -- this prevents even tiny particles of dirt or other material from entering your drip system. As the holes are very small in a drip system, even tiny particles can clog your emitters.
Hose / Faucet connector -- this is a devise with a hose style connection on one end and a PVC connection on the other. Basically it connects you header hose to your water tap (with all the above in between!).
Header Hose or Main Line -- I use a 1/2" PVC pipe. This is the main line that brings water to your valves or drip hoses at your plants.
Watering Your Plants
Other items you will need will depend upon your design but basically the next steps will involve:
Drip Tubing -- we use 1/4" flexible irrigation tubing. This is the hose that goes from your mainline to your plant (whether in the ground or in a planter). This is connected to your PVC main line by punching a small hole in the PVC pipe and using a special adaptor that fits in the 1/4" tubing and plugs into the PVC pipe.
Emitters / Sprinklers / Soaker Hoses -- Extend your drip tubing to the plant you want to water and attach whatever type of emitter you choose. The emitter is attahced with another adaptor (sometimes they are pre-attached to the emitter). You can also run small 1/4" soaker hoses directly from the PVC main line just as you would the drip tubing.
End Caps - all tubing must end either at an emitter or have an end cap to stop excess water from pouring out and wasting your pressure. In addition your main line PVC tube must have an end cap.
How you design your system is up to you and there is no right or wrong. Just remember, the further from the main line the less water pressure so try and connect off your header hose or main line more often rather than trying to water too many plants in a row. Also it's best to stake down your lines. Do not bury your lines as animals can dig them up & eat them plus dirt can get in the system easily.
The tap in the upper right connects (with all the pieces mentioned in getting started) to a brown PVC pipe than runs the perimeter of our vegetable garden. Soaker hoses (or if you prefer small plant specific emitters) run from the PVC pipe along the planted rows.
For our vegetable garden we use 1/4" soaker hose. We use all soaker hoses for two reasons -- most of our vegetables are planted in rows so lines of soaker hose seems to make more sense and because the soaker hose comes in 50foot rolls it was more economical to use what we had. We connected small sections of the soaker hose to the 1/2" PVC pipe in various spots around the vegetable garden and ran these along the planted rows. Shut off valves (one of the many adaptors and fittings you can use) were placed in the middle of rows where we have not yet planted seeds and these can be turned on as we extend our rows.
We also used soaker hoses for the tomato plants although small emitters would work as well. Since the soaker hose came in 50 foot rolls it was more economical for us to use what we had.