About Underground Sprinkler Systems
The key components of an underground sprinkler system include a timer, valves, underground pipes, sprinkler heads and risers that connect the pipes to the heads. We’ll focus on sprinkler heads in this guide, but if you want to learn more about this type of system, including the benefits and details on the parts and steps to install one yourself, see How to Install an Underground Sprinkler System.
To have an effective and efficient lawn irrigation system, you need to have the correct sprinkler heads. Your system manufacturer may include a planning guide that helps you select the right heads for different areas of your lawn, but we’ll give you information on some of the most common types and nozzles, as well as tell you where you might use them.
See Watering Tips to get the maximum benefits from watering. Keep in mind that while using an underground system correctly can use less water than manual watering, you still need to make sure you follow any watering restrictions or guidelines for your area.
The Parts of a Sprinkler
Knowing the key components of a typical pop-up sprinkler head will help you understand how they work and what to look for when planning your system.
- Nozzle: The nozzle disperses the water. Certain types offer different spray patterns and dispense water at varying distances. Some have adjustable patterns or may let you make minor changes to the distance they cast the water. Nozzles may already be attached to the sprinkler body, but you can also purchase them separately and install them yourself.
- Riser: This vertical tube elevates the nozzle. Taller risers give the water more distance and keep it above obstructions. A riser can be stationary, such as in sprinklers designed for shrub beds or flower beds, or it can be part of a pop-up unit, extending above the ground when the system activates. This type of riser, typically 2 to 6 inches in height, is sometimes known as a plunger. The term riser can also apply to the underground vertical pipe segment that connects the body to the water supply pipes.
- Body: This component is the housing (typically plastic) that’s installed in the ground. It contains the spring and, when the system isn’t operating, the riser and nozzle.
- Cap: The cap covers the body and protects the internal portion of the assembly from large debris.
- Wiper Seal: The wiper seal surrounds the riser or plunger, acting as a gasket between the riser and body. It keeps water from leaking from the sprinkler body and helps keep dirt and debris out of the body when the head is above ground.
- Spring: The internal spring elevates the nozzle when the system activates.
- Inlet: The inlet is at the bottom of the body. It fits to the underground riser, connecting the sprinkler head to the supply pipe.
- Pressure Regulator: Available on some models, this device helps maintain a constant water pressure in a system so it can operate efficiently.
- Check Valve: Available on some models, a check valve helps prevent water in the pipes from seeping out of housing and into low areas of your yard once the system is off.
Types of Sprinklers
The two primary types of sprinklers are pop-up sprinklers, which are typically used in lawns, and fixed sprinklers, sometimes known as shrub head sprinklers.
Pop-up heads are the most common types of sprinklers in an underground sprinkler system. The nozzle and riser retract below the surface of the ground when not in use to prevent damage from mowers, pets, foot traffic and more. Once activated, the nozzle rises and begins releasing water.
Static or fixed sprinkler heads are great for flower beds or shrub beds where there’s less risk of damage. These shrub head sprinklers are typically taller, allowing water to reach over plants and other obstacles.
Nozzles
Underground sprinklers use several different types of nozzles. These may be included on a fully assembled component, but you can also purchase the nozzles separately and install them yourself. Nozzles often have one of three spray patterns or arcs:
- Full circle (360 degrees)
- Half circle (180 degree)
- Quarter circle (90 degrees)
However, some have an adjustable or variable arc, letting you customize the nozzle to suit your landscape.
Spray Head
Spray head nozzles are best for a small to mid-sized yard. They dispense water in a spray or mist and typically have a radius between 4 and 15 feet. The nozzle doesn’t rotate. Instead, it has a fixed radius or arc, allowing you to better control the irrigation area and avoid wasting water on patios, sidewalks and driveways.
Specifications vary, but spray head nozzles typically require a water pressure around 30 pounds per square inch (PSI) and irrigate at a rate of about 1-1/2 to 2 inches per hour. They have a relatively high irrigation rate, so they dispense more water quickly, but they’re more prone to clogging than other types of nozzles.
Strip spray heads allow you to create a pattern that will evenly water narrow, rectangular areas.
Rotor or Rotating Head
Rotor nozzles cast one or more streams of water, rotating in a full or partial circle to cover an area. These are suited for medium and large lawns. They need water pressure around 50 PSI and deliver water at rate between 1/2 inch and 1 inch per hour. They have a slower rate than spray nozzles, but since they apply water over a longer period of time, the water has more time to soak into the ground. This makes rotor nozzles a good option for irrigating slopes and slow-draining soils, such as clay, since you risk runoff and waste if you apply water too quickly to these areas. There are two types of rotor heads:
Impact: An impact sprinkler can dispense water over a radius of 80 feet or more, operating with a characteristic ticking sound. A spring-loaded arm continuously interrupts the stream of water to momentarily redirect it, dispersing the water more evenly. On some models, the mechanism remains above ground even when not operating, but there are smaller pop-up versions.
Gear Drive: A gear drive head rotates by means of an internal mechanism. They’re usually pop-up models and operate more quietly than impact heads. Depending on the model, they can irrigate up to a 55-foot radius. Single-stream models have the longest reach of the gear drive sprinklers, but some models have two streams to provide coverage near the head and at a distance. Others emit a mist at the head to irrigate that area with less force. This feature can be useful if you’re watering a newly seeded yard.
Rotary Nozzle
A rotary nozzles spins to disperse multiple streams of water. A rotary nozzle has a watering rate similar to that of a rotor but operates with slightly lower pressure and has a shorter range (usually 10 to 30 feet).
Bubbler Nozzle
A bubbler nozzle puts out a lot of water to saturate small areas of the ground and reach the roots of plants, such as trees or bushes.
Mixing Sprinkler Types
If you’ll be using different types of nozzles in your system, you’ll need a separate zone for each type. Since they apply water at different rates, mixing types within a zone will result in poor performance, where one area of the zone gets too much or too little water.
Preconfigured systems provide tubing, sprinkler heads, fittings, a timer and more to give you everything you need to set up a basic underground system.
Other Watering Options
In addition to underground systems, there are other tools that can help you keep your garden or lawn well watered. Drip irrigation systems are perfect for gardens and planting beds. They’re designed to deliver small amounts of water to keep the root systems of your plants watered. Read our drip system guide to find out if one of these systems is right for your landscape.
Keep in mind you can also find hose-end lawn sprinklers that attach to a garden hose for easy watering, as well as hose-end timers that make controlling a drip irrigation system or lawn sprinkler easier.