Sprinkler Systems – How do they work?

Understanding the basics of lawn sprinkler systems

It’s Saturday afternoon, and you’re wandering through the crunchy grass, wondering what the next step is for you and your lawn. You venture over to the garage and open the sprinkler systems controller box. You push some buttons and maybe turn a knob. At least the water came on, right?

Wouldn’t you feel more empowered to harness the benefits of this investment if you better understood it? I mean, we don’t typically purchase things we don’t understand. What is it about sprinkler systems that seem so helpful yet so confusing? Stick around because we are about to walk through the basics of how a sprinkler system works.

Sprinkler Systems – The Components

A typical residential lawn sprinkler system is made up of several basic components. Now, with all the advancements in technology, there is the potential for MANY water-saving components. Unfortunately, we do not find most of these “extras” installed on most sprinkler systems here in Oklahoma City and its suburbs. 

 For more information on saving on your water bill or repairs, call us at 405-241-4874. — Let’s look at the basic components of a sprinkler system.

• Water supply – Are you on city water? Well water?
• Back-flow preventer – This is a plumbing device that prevents water in the system to siphon back into the city water system. Most city codes require this. Often it is hidden under a fake rock.
• Main-line – The pipe that runs from the backflow preventer and supplies water to the irrigation control valves.
• Zone – Defined watering area. See more under “System Layout and Design.”
• Irrigation control valves – This is the “gate” that activates a zone by allowing the zone pipe (lateral lines) to fill with pressurized water.
• Lateral lines – The pipes that fill when a zone is turned on which supplies water to the water emitters.
• Water emitters – This is the component that discharges water. These are more often referred to by type, such as rotor heads, spray heads and drip line (More on this in the next section.) There are also drip emitters which are a type of water emitter for small areas like flower pots.
• Controller – the brain, clock, timer, programmer – this is the box that is typically in the garage or an outside wall of the house where the magic happens. The controller wires run to each zone valve to turn zones off and on.

Sprinkler System Layout and Design

Installing a sprinkler system starts with a site plan and lots of math. It is not as simple as throwing some heads in the ground so that it looks like “that ought to do it.” In Oklahoma, irrigators are not regulated and it is truly unbelievable how many systems we come across that have absolutely no design consistency. Here are some of the most basic and most important things to get right.

• Zone Layout – Zones should be chosen based on areas of the lawn or landscape that have similar environmental characteristics and preferably similar plant water requirements. For example, Zone 1 may be a shady area, Zone 2 may be a sunny area, Zone 3 may be a low-elevation area, Zone 4 may be a flowerbed, Zone 5 may be a sandy area in the sun, etc. This is how a professional irrigator will “section off” the lawn. Zones should be laid out this way so that we can tailor the water needs according to the area.
  • One other consideration for zone layout is the system water supply capacity. Your water meter (or water well pump) can only supply a certain amount of water in a given amount of time. If the size of the zone is too big pressure will drop. You can’t always irrigate all of a certain type of area on a single zone. For example; You may have a half acre of sunny grass area to water. If you tried to irrigate this whole area with one zone you would have far too many heads and pressure would be weak. A few examples of landscape division by zone for some of our customers can be found below.

• Head Type – There are two basic head types: spray and rotor heads. Spray heads are often referred to as “fan” type heads. They pop up and spray a solid fan of water and are small area heads. Rotors spray a solid stream of water and rotate back and forth. Rotors are large area heads. Most of the time, spray heads and rotor heads have very different water rates. What this means is that a spray head may only need to run for five minutes to “rain” the same amount of water that a rotor head “rains” in 20 minutes or more. If you have a zone that has four rotors and four sprays, you would be significantly over-watering the spray-head areas just to get the bare minimum amount of water on the rotor-head areas. For this reason, these heads should NOT be both found on the same zone. If your system has zones with mixed head types it is almost always worth it to have the system re-worked. Over time the water usage adds up
• Drip line & drip emitters – Drip line is usually a brown tubing that will often be found in commercial landscape flowerbeds and in some new residential construction. Instead of spraying water which is susceptible to wind and over-spray, drip irrigation tubing does just what it sounds like – drips. These zones typically need to run quite a bit longer than spray zones but this is not always the case. It just depends on the vegetation and soil type. Drip emitters are very small water emitters that allow a small amount of water out. Typically, these are found in flower pots or small planting areas.

Putting it All Together

Now that you know some basic terminology and the functions of the components, let’s follow the water through the system.

Joe has his sprinkler system set to run at 5:00 a.m.

1. When 5:00 rolls around, the controller sends an electric signal down tthe wires to the irrigation control valve for Zone 1.
2. The irrigation control valve opens and allows water through as designed. The water begins to move out of the city main and into the tap. (The “tap” is what the city calls a water line that ties on to their water main to run to a meter. The term comes from “tapping” into the water main.)
3. The water moves through the tap and the water meter and up into and through the back-flow preventer. After the back-flow preventer, the water ventures down the sprinkler system main line. It moves through the intricate pipe system towards the open valve – Zone 1. The water makes it to and through the valve.
4. Finally, it works through the lateral lines to the sprinkler heads and other water emitting devices and we find the water being distributed across a nice lawn.

What’s Next?

My hope is that you will gain knowledge about your sprinkler system and be able to recognize when something isn’t working the way it should. If you have identified a problem or are needing help with a more complicated problem, please give us a call at 405-241-4874 and we would be glad to help! We are currently running a special for $29.99 to go through your sprinkler system looking for problems and inefficiencies. Part 2 of this article will be helpful for learning how a sprinkler system controller works. Please stay tuned by liking our Facebook page.