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Planning a drip irrigation system

Designing a drip irrigation system
Compared to conventional sprinkler systems, drip irrigation systems are simple to design, inexpensive, and are easy to install. In addition they can reduce disease problems associated with high levels of moisture on the leaves of some plants. Unlike traditional high volume-high pressure sprinkler systems, which require careful planning, extensive trenching, and special tools and glues, drip irrigation systems can be easily installed above or below ground, without special tools and glue or extensive technical knowledge. These efficient systems deliver water measured in gallons per hour (GPH), and apply water only where is needed. This can improve plant health, conserve water, and reduce the growth of weeds at the same time.

Sketch your property or area
Start by making an accurate top view sketch of the areas that need to be watered. Make sure that you show on the site's outline your home, any retaining walls, sidewalks, paved areas, and water sources accurately and to scale. This will require measuring the area. We recommend using graph paper with small squares. This will make drawing to scale easier. Each small square foot on this manual graph can represent one foot of your property; this scale is usually appropriate for residential landscapes, or you can use 1" graph = 10' of your area.

Create a plant list
Note and list the locations of your small and large trees, shrubs, groundcover, flowerbeds, containers and vegetable garden. Based on the soil type and concentration of plants, you will select the water emission devices and estimate the total flow rate

About the soil
The soil is a storage room for the plant nutrients and the medium through which water and nutrients move. It is the anchor for plants and the reservoir of water for plants' growth. There are various types of soil with different characteristics, which determine what types of dripper or micro sprinkler can be used. In sandy soil, where the water will tend to go straight down, use closely spaced 2 GPH drippers, 10" to 12" apart, or microsprinklers. In loamy soil, the water will move slowly and will spread evenly, so use 1 GPH drippers with 16" to 18" spacing. In clay soil, where water will be absorbed very slowly, use .5 GPH drippers at a wider spacing (18" to 24" apart).

Determine soil types
With a drip system water is applied slowly to the root zone at a single point, it is acted upon by the forces of gravity (downwards) and capillary action (outwards), producing a wetted pattern characteristic of the soil type and the water application rate. To determine which type of soil you have in a given area, take a handful of dry soil, grip tightly and release. Sandy (coarse) soil will crumble and fall apart, loam (medium) soil will hold together but then easily break apart, and clay will mold without breaking.

Select the methods to start a system:

Method 1: Above the ground installation starting from a faucet or anti-siphon valve using only the 1/2" black poly tube as the main lateral and the 1/4" micro tubing as the feeder, and inserting the drippers or micro sprinklers into the 1/2" drip hose or on to 1/4" micro tubing.

Method 2: Below grade installation starting from an in-line valve or battery operated controller and using a 3/4" PVC pipe below grade as the main lateral line, poly tubing above the ground as sub-laterals, and 1/4" micro tubing as the feeder line and inserting the drippers or micro sprinklers into the 1/2" drip hose or on to 1/4" micro tubing.

Method 3: Retrofit a sprinkler system, or a 1/2" riser by removing the sprinkler heads and attaching four, six or twelve outlets drip head, from the drip head extend microtubing to the plants and secure with a stake.

Method 4: Retrofit a riser by using conversion elbow, pressure regulator and swivel adapter and use poly tubing above or below the ground as sub-laterals, and 1/4" micro tubing as the feeder line, and inserting the drippers or micro sprinklers into the 1/2" drip hose or on to 1/4" micro tubing

Select the product to use and where when installing a system
When designing your system, you have various options for your drip, microsprinkler or microsprayers placement, and layout: you can select button drippers, multi-outlet drip heads, dripline, laser drilled soaker hose, drip soaker tape, microsprinklers, sprayers or foggers.

Product Classifications
Depending on the size of the lot or area and variety of plant material, the typical home garden may require one or more of four different types of drip irrigation or microsprinkler in your design layout. Select which products to use based on what needs to be irrigated, in each situation DIG provides an appropriate and efficient irrigation solution.

Category 1: Button drippers, adjustable drippers, multi-outlet drip heads and all our driplines are suited for virtually any layout with plants such as shrubs, trees, vines, roses, foundation plants, and are most efficient when plants are spaced few feet apart.

Category 2: Microsprinklers and microsprayers are best suited for densely planted flowerbeds, annuals, groundcovers, groups or clusters of plants, small slops, and on sites with very sandy soil as water will percolate downward before it can spread far enough. Avoid microsprinklers in areas where it is windy; high winds will disturb the microsprinkler spray pattern. Model #GE200 are excellent starter kits for this type of installation.

Category 3: For containers, potted plants, and hanging baskets, use misters or 1/2" GPH button dripper. Mister is most appropriate for hanging plants and plants that benefit from moist foliage. Potting soils are very porous and misters prevent drainage problems by dispersing the water over a larger area of the soil surface. The mister is an ideal choice for all sizes and shapes of containers. Larger containers may require more than one.

Category 4: Dripline, drip soaker tape, and " laser drilled soaker line are ideal for vegetable gardens, row crops, seed beds, planters, and narrow planting areas. These products will saturate the soil under the entire length of the dripline or drip tape. An excellent kit is the #K007 or a dripline with a 1 GPH dripper every 18.

Determine and calculate water flow requirements
To determine the total flow within a drip system section or zone, add up the total number of drippers and their flow rates. The same method should be used for micro-sprinklers and micro-sprayers. Example: You have designed a system using 40 drippers, consisting of 20 -1 GPH and 20 -2 GPH drippers, plus 2 micro-sprinklers at 14 gallons per hour each.
Calculate total flow rates:
20 -1 GPH drippers = 20 gallons per hour
20 - 2 GPH drippers = 40 gallons per hour
2 -14 GPH micro-sprinklers = 28 gallons per hour
Total flow rate= 88 gallons per hour (GPH), or (dividing by 60) =1.46 gallons per minute (GPM)

If the flow rate from a single poly tube exceeds 220 gallons per hour (GPH) add another poly tube line. If the flow rate from a valve and for a section exceeds 9-GPM (540 GPH), divide the area into multiple sections or zones, each having a different valve. Another option is to divide the area into different sections for each type of system, for example one for microsprinklers in your flower beds, one for a drip system to your shrubs and trees, and one for the soaker tape to your vegetable garden, with a different valve for each of the areas

If in doubt about the capacity of your water source, make sure that no water is being used in the house, and then time how long it takes to fill a measured bucket from one of the outside faucet. For example: open the faucet slowly to until it is fully open and measure water capacity if it takes 20 seconds to fill a 3 gallon bucket, then the maximum flow rate available per hour is 3 gallons x 3 times a minute= 9 gallons per 1 minute x 60 minutes = 540 gallons per hour; 540 divided by 60 = 9 GPM, so you have 9 gallons per hour available from your single water source. Should the system require higher flow rates, divide the system in two by adding another valve.