How to Install an Underground Irrigation System

Why should I install an underground irrigation system?

Increase Home Value and Cost Savings

Underground irrigation systems offer a host of benefits. For starters, the upfront effort and cost pay for themselves after just a few watering seasons. You will see a decrease in your monthly water bill almost immediately. An underground irrigation system can also enhance your home’s curb appeal, which increases marketability and home value.

When properly installed, maintained and operated, an in-ground sprinkler system can easily save hundreds (and in some cases thousands) of dollars in annual water costs. Sprinkler systems allow you to more efficiently regulate water to different parts of the yard, rather than a one-size-fits-all approach.

Time Savings

In-ground systems are also great at saving time. Many homeowners know the frustration associated with dragging hoses around their yards, remembering timing schedules, and trying to spot-correct problem areas. Underground sprinkler systems operate on the “fire and forget” principle: set the system properly and let it run (with only minor tweaks along the way). Ideally, you should set your sprinklers to run early in the morning, between 4:00 a.m. and 8:00 a.m. Watering early in the morning frees up the yard for outdoor activities and allows the turf adequate time to absorb the water before evaporation.

 Sprinklers running

How do I get started installing my underground irrigation system?

An in-ground irrigation system is no small project. It’s one you want to get right because mistakes can be costly and time consuming to fix. But a well installed system will yield results almost immediately and require little maintenance over the years. The following paragraphs explain how to begin the process.

Determine Local Codes

Before digging a trench or installing pipe, check with your local municipality about code requirements for underground irrigation systems, backflow prevention, and anti-siphon valves. Backflow prevention with anti-siphon valves is important to consider because it prevents possibly contaminated water for being drawn back into the main water supply lines when water pressure decreases.

Ask if a permit is required to install a system or if a licensed plumber is necessary to connect your main line. If you live in a freezing area, pipes need to be buried 8-12 inches deep. You may also ask for recommendations on pipe size.

Your municipality may offer the option to use reclaimed water. Reclaimed water is sewage and wastewater that has been treated at a facility. Though the water isn’t suitable for human consumption, it is a great resource for watering yards. Besides being greener (it’s basically recycled water), reclaimed water can be significantly less expensive than regular water. However, certain precautions need to be taken when using reclaimed water, which the municipality will explain further.

Determine Water Flow

Determining available water pressure is an important step. Water pressure affects every aspect of the system including: how many zones will be needed to water evenly, the type and amount of sprinklers to add to the line, and length of watering intervals.


String Test Method

To determine the available water pressure, attach an Orbit pressure gauge (part #53020 or #91130) to an unregulated outside faucet. Unregulated means a line without a pressure regulator. Open the faucet and record the reading. No other water should be running during the test. We recommend you perform this test as close to the time of day when the sprinkler system will be operating. Pressure will generally be higher in the mornings. To be most accurate, take several readings at different times, even different days, and record the lowest one.

pressure gauge

Next determine whether your main water line is copper, galvanized, or PVC. If you are unsure of your pipe material or size, your municipality can tell you. Then, determine your pipe size. You can do this by performing a simple string test. To do this, wrap a piece of string around your main water service line then measure the length of the string. Use the table to convert the string length to pipe size diameter.

string test

Knowing the amount of available water pressure and the size of your main line will allow you to calculate water flow. Water flow is measured in Gallons per Minute (GPM). Use the following chart below to complete the calculation. Water pressure (measured in PSI) is along the top of the graph. Locate the box that coincides with your pressure reading. The vertical boxes along the left side of the chart show different sizes of mainline pipe. Locate the size that corresponds to the string test you performed. You will find your GPM where your PSI rating and your main line measurement intersect.


Bucket Test Method

Water pressure can also be found by performing a bucket test. Simply time how long it takes the unregulated outside faucet to fill the bucket. Then, multiply the size of the bucket used by 60. The result will be your water flow in Gallons per Minute or GPM. For example, if you filled a 5 gallon bucket up in 30 seconds you would take 5 gal. / 30 sec. *60 = 10 GPM. This would equate a 10 Gallon per Minute water flow.

Measure and Draw Your Property

house imageThe final step is to measure and draw your property. You can draw your property by hand, but this process is often tedious and time consuming. To solve this, Orbit has created an online tool to make the process a breeze. Simply visit our Sprinkler System Design Tool at where you can import an overhead photo of your property from Google Maps and then trace over the features of your yard. The system will even let you distinguish various areas of your yard, such as lawn, flowerbeds and garden areas, and then you can specify the type of sprinklers you want in these areas.

designerAfter you have entered all the necessary information, the Orbit Sprinkler System Design tool will automatically draw an efficient sprinkler system for your yard.

While the above steps may seem like a lot of work, we can’t emphasize enough how important it is to design your system right. Any errors in this planning phase will affect the design and function of your system.

Used correctly, the Orbit Sprinkler System Designer allows you to plan and design a system that runs optimally with little maintenance.

Check back next week for part two of our series.