The concept of drip irrigation systems is simple: Tiny holes inserted at various points along a hose allow small quantities of water to trickle slowly into the soil over long periods.
The disadvantage of sprinkler systems is that a lot of water is wasted, owing to evaporation of the spray droplets as they fly through the air. Drip irrigation systems use less water, because it’s applied directly where the plants need it most.
Whether your garden is ornamental or food-producing, a drip irrigation system can be used with equal success.
Benefits of a Drip Irrigation System
- Saves Water: Studies show that drip irrigation systems use 30 – 50% less water than conventional watering methods, such as sprinklers.
- Improves Growth: Smaller amounts of water applied over a longer amount of time provide ideal growing conditions. Drip irrigation extends watering times for plants, and prevents soil erosion and nutrient runoff. Also, because the flow is continuous, water penetrates deeply into the soil to get well down into the root zone.
- Discourages Weeds: Water is only delivered where it’s needed.
- Saves Time: Setting and moving sprinklers is not required. A timer can be added to the system for automatic watering.
- Helps control fungal diseases, which grow quickly under moist conditions. Also, wet foliage can spread disease.
- Adaptable: A drip irrigation system can be modified easily to adjust to the changing needs of a garden or lawn.
Simplest Drip Irrigation Methods
Start by drawing a map of your garden and yard, showing the location of plantings. Measure the distances required for lengths of hose or plastic tubing to reach the desired areas.
Soaker hoses”sweat” water from tiny holes along the length of the hose. They emit water slowly and continuously along the hose length, with a 2-3′ watering width. These hoses can be set on the ground or buried under mulch. They have brass fittings which easily attach to any hose or hose bib.
To install, simply lay along the ground or weave between plantings, cut to length, and add hose fittings and end caps. Best for relatively level sites and runs of 100 feet or less, soaker hoses operate with as little as 8 lbs of water pressure. Regulators are available for sites which are more sloped.
Sprinkler hoses spray a fine mist of water into the air. They look like flat hoses with perforations all along their length. For a drip-irrigation effect, simply turn sprinkler hoses over, so the mist is directed straight into the ground. Sprinkler hoses have fittings and end caps for simple attachment to any hose or bib.
Sprinkler hoses are easy to install: just lay the hose on the ground and screw to the hose line. However, because they are flat it’s more difficult to weave around tight curves. The spray can also cause erosion if the water pressure is too great.
You can also make your own sprinkler hose from old garden hose by piercing holes in a pattern to direct the flow where you want it. Use a hot needle to pierce the hose, and be sure to crimp the end of the hose line.
Use “Y” connectors to add more lines. These are available in plastic or brass. Lay the hose on the ground and work it between plantings and along rows as desired. Be sure the hose ends are closed.
The advantages of an above-ground “soaker” system are low cost, ease of installation, and ease of moving the system during cultivation and planting. And no assembly is required.
The disadvantage is the less precise control of water distribution: the entire hose line is watered, not just specific spots along the line.
You can also use an automatic timer for this system. Ask at your local garden supply, or at the online links listed below, for more information regarding specific models and features.
Measure your plot to determine how much tubing you’ll need. These measurements don’t have to be exact: the tubing comes in a large roll, which is cut to length in place, as you go. The total run of submain, on any one circuit, should not exceed 400′. Note how many ‘elbows’ or ‘tees’ you’ll need.
Decide where you want the emitters and how many you’ll need. Space emitters 12 – 20″ apart depending on soil type. Sandy soil, for example, will require closer spacing than loamy soil. A one gph (gallon per hour) emitter will cover a 12″ diameter in sandy soil. When installing the system, begin with just one emitter and test for wetness diameter. For large plantings, shrubs, or trees, several emitters may be used around the planting to encourage the roots to grow outward in all directions.
Components for a snap-together system often come in kit form. Just show your plan, with measurements, to your drip irrigation supplier. Parts from different systems are usually interchangeable. The basic parts you’ll need are:
- Water pressure reducer
- Anti-siphon device
- 1/2″ or 5/8″ flexible polyethylene tubing (for submain)
- 1/4″ tubing with pre-punched holes (for drip lines)
- Connecting ‘tees’ and ‘elbows’
- Automatic timer (optional)
1. Attach anti-siphon, filter, and pressure-reducer to hose bib. If you are using an automatic timer (below), it will be installed above the filter.
2. Run the submain along the ground according to your planned layout, starting from the hose bib. Using a small-blade utility knife, cut the tubing where the water system changes direction (elbow) or branches in two directions (tee). Snap the elbows and tees into place. The submain is now installed.
3. Attach emitters to the submain. Simply punch a hole using an awl or punch tool supplied with your drip kit, and push the barbed end of the emitter through. Install just one emitter at first, and run the water for one hour to test for wetting diameter. This will guide you in spacing the emitters for watering coverage. Don’t forget to cap or crimp the end of the submain before testing.
4. A “sprinkler-emitter” (left) can be installed anywhere in the line where you need to water large areas. Use small, connecting barbs to attach the 1/4″ tubing to the submain. The sprinkler-emitter has a stake to raise the head well above ground.
5. Install “drip lines” (below) for area watering of flower beds and ground covers. Simply punch a hole in the submain and snap on the drip line using small connectors which come with the drip line.
Drip lines emit 1/2 gph through holes spaced about one foot apart.
6. Seal off the ends of the submain. Simply fold end back over itself and fasten with copper or galvanized wire, or hose clamp. Some kits provide small plastic “figure-eight” style clips which secure the folded-over tube end.
A convenient option in a drip irrigation system is an automatic timer. Battery powered timers let you set the frequency and duration of watering, and allow you to set different watering schedules for different applications. With automatic shut-off, you can set the timer and leave. Installation is simple: just screw the timer in line above the water filter.
Drip Irrigation Tips
- Prior to installation, leave tubing in the sun for awhile to warm.
- Small plastic stoppers, also called “goof plugs”, can be used to plug the holes on the submain if you decide to remove emitters from any section of the system.
- Reduce watering need by planting near a low hedge or wind barrier. Reducing the wind will reduce water loss by evaporation.
- Don’t overwater. One inch of water per week will suffice for plants with average water requirements. A one gph emitter will deliver this amount of water in about one hour. Hot climates often require the equivalent of 2” per week of rainwater. It’s best to water deeply, but infrequently. There should be no puddles around the emitters.
- Check your system by sticking a pencil or sharpened stick into the soil between emitters to see if moisture is present. If the soil is moist, the stick will slip easily into the ground. It’s easy to add emitters or change their spacing.
- Drip irrigation systems left above ground tend to clog less than buried systems, and they are easy to lift when cultivating or planting. Cover the soil with mulch to conceal the tubing and further reduce evaporation. If you are going to bury the system, leave the trenches unfilled until you’ve tested the completed system. Make a diagram of the system if buried.
- If you live in a colder climate, drain your system at season’s end. Simply unplug the end stoppers, or fold open the crimped end of the lines. Tie a plastic or cloth wrap over the open end of the line to keep it free of debris and bugs. Draining the line prevents any breakage due to freezing. Store the filter, pressure reducer, and timer indoors for the winter.
- If your garden has raised beds, you can use ‘elbows’ and ‘tees’ to lead branch lines up into the bed.
Online Sources For Drip-irrigation Supplies
Pro Series Double-Wall Soaker Hoses
These highest quality soaker hoses are double-walled so they don’t break down under prolonged sunlight, and they are flexible, so they’re easier to weave around plants. The porous walls are thickened for slower and more uniform water distribution. Available in various lengths, they can be strung together for any distance while retaining consistent watering application.
‘Save A Drop’ Water Meter
The Save A Drop Meter is a simple way to make sure your plants aren’t being overwatered. The easy-to-read LCD display calculates both single-use and accumulative watering volume, giving you the information you need to turn off your hose or drip-irrigation system when the time is right.
Rain Catchment Systems
This 54 gallon catchment barrel collects rainwater from your roof. The system includes a large capacity overflow tube and a spigot at the base which connects to your garden hose. Besides helping to conserve water and reduce water bills, this provides buffer storage for drip irrigation systems.