An underground irrigation system delivers water to your landscaping at the right time, and in just the right amount, so you don’t water too much or too little. It’s relatively easy to install and makes a good DIY project.

You’ll also save money doing it yourself. A professionally installed system for a typical ¼-acre lot is $3,000 to $4,000. You can DIY it for under $1,500.

The heart of an underground system is pop-up sprinkler heads. When working, the heads raise up a few inches to spray water on your landscape. When not in use, they drop to ground level so you can mow or walk right over them.

Plus, today’s systems are pretty darn smart. Automated features decide when it’s been raining too much or too little, then adjust the amount of water your landscaping gets. That lowers the worry quotient for you, heads off costly over-watering, and makes the whole system almost maintenance-free.

Getting in the Zone

An irrigation system divides your property into zones. Each zone can be different in terms of the amount of water it gets, and at what time of day it’s watered. Examples of zones include:

  • Lawn zones have pop-up heads with just the right spray radius and range to cover a broad area of grass.
  • Landscaping zones have high-rise heads to water shrubs and ground cover.
  • Flower and vegetable zones may be equipped with bubblers and tiny spray heads that gently water plants without bruising edibles or knocking petals off blooms.

Everything functions on an automatic timer that controls water flow throughout the system. You can elect to include sensors that monitor rain and humidity — self-adjusting timers that prevent unnecessary watering.

Start with a Plan

Your irrigation journey starts with a plan that maps out:

  • Your yard, house location, and major landscaping features, such as trees.
  • Your irrigation zones.
  • The location of sprinkler heads and bubblers.
  • The location of underground water supply lines.
  • The location of a water-supply shutoff valve.
  • Any automatic sensors.

But planning is a challenge for first-timers. Manufacturers recognize this hurdle and go out of their way to provide planning help. After you give them some info on the size of your lot and your water supply system, they give you an irrigation plan tailored to your property.

You’d be crazy not to take advantage of their services. For one, they’re free. Second, they’re very thorough: downloadable guides and step-by-step videos take you through every part of creating a home irrigation system.

For example, Rainbird and Toro offer planning guides that show you how to make a scale drawing of your property, and how to easily gather information on your water pressure and water flow rate that’ll help determine the design of your system.

When you mail in the drawing and info, the manufacturer returns a custom plan with a materials list and detailed installation instructions, all designed specifically for your property. Replies take several weeks. For a small fee ($20-$30), you can have your plans arrive in a few days.

Orbit shows you how to use Google Maps to make a scaled plan of your lot without ever stepping outdoors. Plans are available instantly.

Get Ready to Dig

Your next job is trenching — digging channels in your yard for the water supply lines and sprinkler heads. With plan in hand, mark out the locations of the irrigation lines using string lines, powdered chalk, or lawn marking paint — it comes in a spray can specially designed to be used upside down ($5).

At this point comes a heads-up about your local building codes. You’ll need to ask a couple of questions of your local building and planning commission:

  • Do I need a permit?
  • Is a licensed plumber required to connect my irrigation system to my home’s water system?
  • How deep should the trenches be? (Most building codes require you to dig down 18 inches to protect the water lines from freezing — in colder climates the required depth is more.)

Unless you relish the idea of hand-digging several hundred feet of trench, rent a gas-powered trenching tool for $100–$160 per day. This walk-behind tool makes short work of deep, narrow trenches.

Very important! To prevent injury, be sure to have all utilities marked before you begin digging. Call your local utilities or dial 811.

Installing the System

With excavation complete, you’re ready to buy all the stuff you need. You’ll build your system from plastic pipe, either rigid or flexible PVC. Both are good choices and use the same methods of assembly.

  • Rigid PVC pipe is inexpensive — ¾-inch diameter pipe is about 25 cents per lineal foot.
  • Flex PVC costs more at about $1 per lineal foot of ¾-inch-diameter pipe, but it installs faster, there are fewer connections, and it’s more forgiving of trenches that aren’t perfectly straight.

There are lots of other components, including sprinkler heads and bubblers, and each type has different ranges and arcs — the size and shape of their spray. That’s another reason to check out the manufacturer’s guides — they’ll give you a complete materials list.

Unless you’re an accomplished DIY electrician and plumber, you’ll probably need a bit more professional help:

  • An electrician to extend a circuit to the automatic timer; figure 2-3 hours at $90-$110 per hour.
  • A plumber to tap into your household water system. Budget another $200-$300.

Ready to Call In the Pros?

If the DIY approach is more than you want to tackle, or your lot is larger than a third of an acre (14,500 sq. ft.), consider hiring a pro. Expect to pay $3,000-$4,000 to have an underground irrigation system installed on a ¼-acre lot.

Aside from saving you a lot of work, a pro is going to get the job done quickly and with minimal disruption. He’ll also come with knowledge of what design best suits local conditions.

Good Tips for Watering Your Landscape

  • Check out these low-cost, low-maintenance DIY watering systems.
  • Planning a trip this summer? Here’s how to water while you’re on vacation.
  • Dry spells are hard on your plants. Make sure you know how to water your plants during a drought.