Irrigation systems are automatic watering systems designed to deliver a controlled flow of water for the growth of plants. Growing emphasis on water conservation is making it more important than ever to use the most suitable irrigation system for lawns and gardens. While above-ground spray systems have been the traditional choice for water application, in-ground applications like drip irrigation are gaining in popularity because of the unique cost and water conservation advantages these systems offer. This guide will explain the difference between in-ground and above-ground irrigation systems, the basic components used in each system, the applications they are best used for, and what to look for in making your selection.

In-ground Irrigation
An in-ground irrigation system disperses water through sprinklers attached to risers connected to a network of underground pipes that run throughout your lawn. It can also include a drip system that disperses water through emitters directly to plants' root zones in a slow, precise application, producing deeper root growth and more abundant foliage for garden favorites like perennials, annuals, shrubs, and ground covers. When properly designed, drip irrigation maintains an optimum balance of water and air in the root zone while reducing water wasted due to the sun and wind. 

Drip irrigation offers many money- and time-saving benefits. Delivering water directly to plant roots saves you money by reducing up to 70% in water waste from evaporation and run-off.  It saves you time by replacing hand watering, and reduces yard maintenance by delivering water directly to plants, reducing weed growth. 

An in-ground irrigation system is composed of:

• Valves

• Pipe and Fittings

• Sprinklers

• Risers and Flex Assemblies

• Drip Tubing

• Timers

Valves
Valves turn the flow of water on and off for your irrigation system. The two types of valves used in irrigation are anti-siphon and in-line. They may be manual or electronically controlled, or both. Electronic valves often provide more options and features and are connected to a timer for automatic operation. 

Refer to the table below to learn more about each type.

Type	Description	Points to Consider
Anti-siphon Valve	Combines functions of a valve and atmospheric backflow preventer. Controls the flow of water in one direction, protecting the general water supply from backflow contamination.	Install above ground 8 to 12 inches above the highest sprinkler head in a location where water can flow away from the valve Used where local codes do not require a pressure vacuum valve
In-Line Valve	Has no integrated backflow protection.	Install below ground level in a box that allows access for maintenance and inspection. Typically require a separate back flow device. Can be installed out of sight for uncluttered landscape appearance

Local codes will typically define which valve you should use.

Pipes and Fittings
Pipe used for irrigation includes:

• PVC – Rigid pipe available in sizes ranging from ¾" to 1 ½".

• Polyethylene tubing – Flexible pipe that comes in rolls from ½" to 2". Typically used in climates where freezing occurs.

Plastic pipes are connected using slip fittings, which glue together. Threaded fittings are used to connect pipe to valves and to risers for sprinklers.

Sprinklers
The type of sprinkler head you choose should cover the area adequately and apply water only where it is needed. The two basic types of sprinklers for in-ground applications are rotor and fixed, or spray, heads.

• Rotor systems spray a rotating stream of water and have a lower application rate than fixed spray heads, making them more suitable for slopes.
  
  

• Fixed spray heads disperse water in a set pattern at a high application rate and are most suitable for small level areas.

Refer to the table below for a comparison of sprinkler types and their applications:

Type	Design	Common Use	Placement	Spray Distance	Features
Gear Rotor	Rotor/Gear Heads      Pop-Up Rotor	Medium to large lawn areas Large lawn areas	Up to 45' apart      Up to 45' apart	15' − 45' apart      20' - 45' apart	· Quiet · Installed on a riser       · Ideal for shrubs     · Nozzle rises up when watering and retracts below ground when not in use · Quiet
Impact Rotor Fixed	Impact Heads Pop-Up Impact Heads Shrub Spray Bubbles Pop-Up Fixed Spray	Up to 45' apart Large lawn areas Shrubs and beds Shrubs and trees, beds and gardens Small lawns	Up to 45' apart 25' to 45' Up to 15' 3' to 5' apart Up to 15'	35' − 45' 35' − 45' 8' −15' 0' − 2' 5' − 15'	· Use installation riser · Good for large large shrub areas or slopes · Wind resistant · Work with well or dirty water · Pop-up or flush style · Wind resistant · Sit in a canister below ground · Riser installation clears foliage · Use for slow deep watering · Economical · Use varying nozzles to create patterns

Another important component of a sprinkler irrigation system is the riser. 

Risers
Risers are used to elevate spray coverage. They can also be used to add a few inches to improve the positioning of the head, and should not be used near sidewalks and driveways. 

• Risers are available in ½" and ¾" diameters

• Risers typically span distances of 1" to 12"

• PVC is durable and more economical than metal

Refer to the table below to learn more about the types and applications of risers:

Type	Materials	Points to Consider
Basic	Metal PVC	· Quiet · Also known as "nipples"
Cut Off	Polyethylene	· Provide installation flexibility  · Come in 6" lengths  · Can be trimmed in 1/2" sections
Flexible	Polyethylene	· Allow movement if sprinkler head is hit, lessening chance of the head loosening or breaking · Provide greater length · Require a slightly larger upfront investment

Flex Assemblies
Flex assemblies, also known as "Funny Pipe™", are an alternative to risers to for connecting sprinklers to pipe. Flex assemblies let you place sprinklers at the correct depth without cutting and gluing PVC risers and are useful when installing or relocating sprinklers in hard-to-reach areas. A variety of tee, elbow and adapter fittings provide flexibility and customization, allowing placement of funny pipe and sprinkler heads exactly where you need them.

Drip
Drip tubing can be installed in conjunction with an in-ground irrigation system. While the hose itself is typically laid above ground, it can be linked to the in-ground system by connecting to a riser. Drip hose is available in ½” and ¼” diameters and can be purchased with pre-installed emitters that apply water very slowly directly to plant root zones. This makes drip irrigation especially effective for planter beds, ground cover and gardens. Drip systems provide the greatest flexibility and most efficient watering system. There is a wide range of specialty drip product that can be mixed and matched to create a drip system specific to your landscape.

Timers
Timers tell valves when to open and close to start and stop watering.  They allow you to program schedules for watering different areas, or zones, in your landscape automatically at a given time of day on specific days of the week. Zones are areas of your yard with varying water needs operated by a single valve. When programmed properly, timers can help you conserve water as well. 

• Single-program timers water all zones on the same day and are best for basic lawn watering.

• Multiple-program timers allow different zones to operate independently. Zones often require different amounts of water on varying schedules, i.e., lawns every day and beds every three days.

• Look for a timer that can handle at least as many zones as you currently have

• If you prefer to install your controller outdoors, be sure it is housed in a weather proof outdoor cabinet.

Above-ground Irrigation
Above-ground irrigation systems are most effective for watering small or large open areas like lawns. They distribute water quickly over a large area by throwing water through the air using stationary, oscillating or rotating spray heads arranged at regular intervals to apply water in a uniform manner. Above-ground irrigation systems consist of hoses, hose bibbs, sprinklers, and hose tap timers.

Hoses
Hoses are available in a variety of diameters, length and materials. 

½" hose carries 9 gallons per minute

5/8" hose carries 17 gallons per minute

¾" hose carries 23 gallons per minute

Lengths range from 25' to 100'. The length of the hose affects the amount of pressure at the far end, so choose a length appropriate to the distance of the area you are watering for maximum effectiveness.  Hose materials vary from inexpensive, lightweight reinforced vinyl to heavier and sturdier rubber. Composite rubber/vinyl hoses are a good solution for frequent use. When selecting a hose, be sure it matches the diameter of your hose bibbs. 

Hose Bibbs
Hose bibbs are the familiar threaded faucets on the side of your house that provide water to your garden hose. They are typically ½" or ¾" inch male threaded connections. Besides the standard hose bibb, types include anti-siphon, which prevent wastewater from backflowing into your drinking water supply, "rost-free" hose bibbs that won't freeze in the winter, and anti-siphon attachments that thread onto a standard hose bibb valve.  Installing hose bibbs in your yard in convenient locations away from your house is one solution to dragging heavy hose around the yard.

Sprinklers
There are a variety of sprinklers from which to choose for above-ground watering. Refer to the table below to determine which type of sprinkler best meets your needs:

Sprinkler Type	Benefits	Ideal Usage
Stationary (Small hose end sprinklers)	Fast and precise watering Water hard-to-reach areas Economical Multiple types	Small and medium areas Gardens Lawns Shrubs and beds
Oscillating	Gentle watering Even coverage Rectangular or square pattern Above ground – flexible placement	Medium- and large-sized areas Front and back lawns Newly seeded areas
Rotating	Puts water down at a low rate, allowing soil to absorb most of the applied water with little loss due to run-off Adjustable patterns Even distribution Work quietly	Medium and large areas Gardens Front, back and sides of house

In addition to sprinklers, soaker hoses release water slowly through thousands of tiny holes and are excellent for localized watering of long strips of lawn, gardens and landscaping. Drip hose and tubing can also be connected to the hose bibb to deliver water efficiently to planter beds, decks or patios, pots and hanging plants. Drip irrigation systems can be used in green houses or as a misting/fogging system to cool patios and decks on hot summer days.

Hose Tap Timers
Hose-end timers save you time and money by converting an ordinary hose into an automatic sprinkler system. They automate watering for drip or hose-end sprinkler zones and are battery operated so no wiring is required.