Drip Irrigation Installation Guide
A properly designed and installed drip irrigation system, sometimes called micro or trickle irrigation, dampens areas where a whole-lawn sprinkler system fails to reach effectively. A drip irrigation system accomplishes this through a series of strategically placed emitters that are spaced throughout the target area. The type of soil and each plant's individual needs determine the spacing and coverage of the emitters. Because drip irrigation concentrates water in a selected area, it reduces the water runoff and evaporation problems inherit with a sprinkler system. A drip irrigation system's versatility make it a cost-effective and environmentally friendly solution for both homeowner and professional alike.
Many drip irrigation systems use a nearby hose bib as a water source; some tap into an existing sprinkler pipe. The hose bib option keeps the drip irrigation timer, if used, independent from the timer operating the sprinkler system. Drip irrigation systems use flexible pipe, threaded and push-on fittings that do not require PVC cement.
Drip irrigation has both above and below ground applications. Hiding the drip tubing under mulch or light ground cover enhances visually sensitive areas, such as flower beds and walk ways. Many vegetable gardeners stake drip irrigation tubing above ground. This method allows easier maintenance and the ability to replace or remove emitters without digging up the tubing.
Both above- and below-ground applications have different types of emitters available: including drip heads, micro sprayers, drip lines and soaker lines. Water dribbles from a drip head, soaking the soil around a single plant. Micro sprayers throw water into the air like a whole-lawn sprinkler system and can cover several feet in each direction. A drip line has evenly spaced ports along its entire length. Soaker lines sweat along its entire length. Drip heads and micro sprayers are measured in GPH, gallons per hour. To help match the system's design to the landscaping, manufacturers offer micro sprayers with 90-, 180-, 360- degree and fully adjustable nozzles. Gardeners often plug multiple types of emitters into a single drip line. This lets them water several different plant species, anything from corn to radishes, off of a single line.
Drip Irrigation System Design
From the simplest system to the most complicated, all drip irrigation systems have a few basic things in common: a water source, pressure reducer, tubing, fittings, and the emitters. Drip irrigation systems often connect directly to an outside hose bib and a battery-operated timer controls the run time.
Before buying materials, create a diagram of the landscaping and the drip irrigation system's layout. Take note of the water source and the type of connection. When using a hose bib as a water source, buy a timer with female hose thread intake port. When connecting to an existing sprinkler system, buy a timer with a female pipe thread intake port. Layout the placement of the 1/2-inch poly pipe trunk line and each branch line. The 1/2-inch poly tubing used in drip irrigation has a maximum flow rate about 220 GHP. Mark each emitter's placement on the map and circle the emitter's coverage. Label each emitter and its type, such as .5 GPH drip or 10-GPH 180-degree sprayer. Total the emitter's flow rate. If the flow rate exceeds 220 GPH, either spit the system into two sections or remove enough emitters to drop the total below 220 GPH. Estimate the material needed, using the layout as a guide. A careful layout of the drip irrigation system reduces material waste and coverage overlaps.
A typical drip irrigation system has a timer, backflow preventer, a filter, pressure regulator, tubing adapter, 1/2-inch poly tubing and fittings, emitters and 1/4-inch micro tubing. The backflow preventer stops irrigation water from contaminating the potable water supply. A pressure reducing fitting keeps the water pressure at a safe level, usually 25PSI, for the poly tubing. The 1/2-inch poly tubing connects to the water supply with a tubing adapter, sometimes called a swivel adapter. Each branch line requires a tee-fitting and and end cap.
Either buy each part individually or purchase a manufacturer prepackaged startup kit. A basic startup kit contains everything needed for a simple system: including a pressure reducer, 1/2- and 1/4-inch tubing, tubing fittings, and several different emitters. Usually a startup kit does not contain a timer. Many homeowners find that one of the manufacturer's prepackaged drip irrigation startup kits are perfect for their watering needs; extra lines can be added at a later date.
Before digging, locate all underground pipes and wires, including any phone or cable wires. If you are not sure of the locations, call the appropriate utility company.
Installing a Drip Irrigation System
Position the drip irrigation system's timer, if used, against the water-source. Hold the timer's readout screen in the appropriate position and hand tighten the timer's intake port. Screw the female end of the backflow devise onto the timer's male port. Systems connected directly to an irrigation-only water source do not use a backflow devise. Attach the sediment filter. if used. Always use a filter when using well water. pressure reducer. Mount the swivel adapter. Fully tighten each connection. A system connected to a whole-lawn sprinkler system only uses the swivel adapter.
Map out the tubing on the ground. If installing a subsurface system, dig the trench for the tubing. Lay stakes on the ground every 3 to 4 feet.
Route a section of 1/2-inch tubing along the system's main or trunk line, working out from the swivel adapter. Insert the end of the tubing into the swivel adapter. Push the pipe until it's end hits the fitting's backstop. Adjust the tubing's position, as needed, and lock the tubing into place with the stakes. The stakes hold subsurface tubing to the bottom of the trench. Cut the tubing with PVC cutters and push an end cap onto the tubing.
Remove a 1-inch section of the tubing at each branch line. Push each cut end of the tubing into a tee-fitting. Position a section of tubing along one of the branch lines. Push the end of the tubing into the Tee's remaining port. Stake the tubing in place and cut the end of the tubing to size. Install an end cap. Repeat this step for each branch line.
Layout the emitters along the tubing, using the schematic as a guide. Make a hole in the tubing with a micro-tubing punch. A micro-tubing punch makes a perfectly sized round hole. Force the appropriate emitter or fitting into the hole. If running a section of 1/4-inch tubing, push a 1/4-inch coupling into the hole and run the tubing as needed. If using staked sprayers or stand alone emitters, force the fitting on the end of the sprayer's tubing into the hole.
Turn the drip irrigation system on and check each fitting for leaks. Tighten any loose parts. If the tubing and fittings become disconnected, check the pressure regulator. Inspect and clean any emitters that do not produce water. Arrange each adjustable emitter's distance and pattern setting to meet the landscape's shape
Sometimes a vegetable garden's irrigation requirements change and once useful branch lines or emitters produce excess water in a certain area. Instead of completely redesigning your drip irrigation system, use goof plugs to cap redundant and unnecessary drip lines or emitters. If needed, the plug can be removed at a later date.
Adding a Drip Line to a Sprinkler System
Certain areas, like a narrow row of plants next to a walkway, only need a small amount of water applied to the root base. Installing an entire drip irrigation system would be cost prohibitive and unnecessary. However, tapping into the pipe below a nearby sprinkler head and running 1/4-inch drip or a soaker line to the problem area possibly solves the issue.
Remove the soil surrounding the chosen sprinkler head, exposing the sprinkler system pipe underneath. Remove the sprinkler head from the pipe's male adapter. Attach the appropriate micro-tubing adapter onto the male threads. When reusing the sprinkler head, screw an extension riser with a 1/4-inch barbed port onto the male adapter. Install appropriate sprinkler head onto the extension riser's threads. To eliminate a sprinkler head; screw a micro-tubing adapter, either single or multi port, onto the male threads.
Position the micro tubing along the landscaping, as needed. Push one end of the 1/4-inch micro tubing onto a micro-tubing adapter's barbed fitting. Repeat this for each piece of micro tubing. Either attach an emitter to the end of the tubing or force a goof plug into the end of a section of drip tubing. Stake or bury the micro tubing.
If the extension riser pushes the top of the sprinkler head well above the surface of the soil, either compensate with a smaller head or adjust the male adapter's depth. If the male adapter connects to flex pipe, remove some soil from underneath the pipe and reposition the adapter. If the male adapter attaches to hard PVC, cut the PVC and cement a new adapter at the correct height.