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Installing Drip Irrigation

Drip irrigation installation can be a complex process, but even if you decide to hire a professional, learning how an irrigation system is installed will be very useful information to have.

Preparation

Before you dig in, you'll want to make sure you have everything you need.

  1. Take another look at your irrigation plans and review the basic design and irrigation components.
  2. Limit confusion during the purchasing process by refreshing your understanding of the individual components.
  3. Make a shopping list. Take your shopping list and irrigation plan to an irrigation supply store.
  4. Recruit the help of an employee to make sure the basics are covered and make brand recommendations.
  5. Try to purchase all of the equipment at the same time, and stick with one brand, especially for emitters. Don't forget the little things like pipe cutters, primer, marker flags, paint, glue and sturdy gloves.
  6. Also, pick up some extra irrigation line and fittings in anticipation of unexpected problems.
  7. Use temporary marking paint to mark the path of irrigation lines and the location of valves and components. This visual guide will help you determine where to dig.

Installation

The process of installing an irrigation system can be broken down into the eight simple steps listed below:

  1. Backflow prevention assembly
  2. Valve box (includes valves, filter and pressure regulator)
  3. Dig trenches
  4. Pipes and tubing
  5. Irrigation clock
  6. Connect clock to valves
  7. Emitters and microtubing
  8. Backfill

Backflow prevention assembly
Determine a location for the backflow prevention assembly. The most common type used on homes in Southern Nevada is called a pressure vacuum breaker (PVB). It should be at least 12 inches above the highest irrigation device and 12 inches away from any walls to allow for access. If you have a large hill with irrigation on your property, the PVB should be installed higher than the hill, or you can install an additional PVB at that location.

City codes require that a backflow prevention assembly must be included in your irrigation system. The backflow prevention device stops irrigation water that potentially carries chemicals such as fertilizer or weed killers from flowing backward into your home's drinking water. While home builders in Southern Nevada typically install a PVB during construction, changes to your landscape may require moving it to a higher elevation or new location. A plumbing permit, obtainable through the city or county, is required for installation. Call before installation to get clear code requirements.

Learn more about irrigation components, including what they look like and how they work.

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Valve box (includes valves, filter and pressure regulator)
The valve box is buried underground and protects the valves, filter and pressure regulator. To install the valve box, follow these steps:

  1. Wet the ground to soften for digging.
  2. Dig a well for the underground valve box and a trench six to eight inches deep leading from the PVB to where you will install the box. The well should be deep enough for the box to sit about two inches above grade when inserted, making it level with the landscape once inserted.
  3. Fill the bottom of your well with one to two inches of gravel to aid drainage. Without the gravel, water can pool and enter the box, making it a muddy mess.
  4. Schedule 40 PVC pipe should be laid in the trench out to the location where your valve boxes will be situated. There may be more than one location, such as the front yard and backyard, but keep the valves close to each other.
  5. Place valves in the ground and connect them. Valve assemblies should have enough room around them to allow access for maintenance. Put a maximum of three valve assemblies in one box. Mark each valve assembly with paint color-coded to match your irrigation lines, so you know where each assembly provides water.
  6. After the valves are installed, attach a filter and pressure regulator to each assembly. Position the filter so you can remove the cap and the filter easily as it will need to be flushed periodically. The pressure regulator can be placed outside the valve box if necessary because there is no maintenance involved.
  7. Place the box over the valves. It may be necessary to cut holes in the sides of the box for the pipe to exit in the correct spot. Level the valve box by placing bricks or blocks underneath.
  8. Wrap the open areas around the exiting pipes with fabric or tape to keep soil from entering the box. Replace soil around the outside edges of the box, but don't fill in your trench as you'll use it to run wires to your irrigation clock later.

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Dig trenches
Start by digging trenches from your valves and run them everywhere you plan to lay pipe and/or tubing. PVC pipe needs to be at least 12 inches deep, while the poly tubing used for drip irrigation only needs to be six inches deep. Digging trenches is hard work, so make the most of them by using the same trench for different landscaping needs. Irrigation and lighting wires can be run in the same trench. Trenchers are available at equipment rental stores, but you will still need to do some trenching by hand around corners, in small areas and around tree roots.

Pipes and tubing
Your landscape irrigation system will use two types of pipes, PVC pipe and PE tubing (poly-tubing). To install pipes and tubing, follow the steps below:

  1. Run Schedule PVC from the mainline to the backflow prevention assembly and from the assembly to the valves.
  2. After the valves, use PVC for above-ground irrigation such as spray heads and rotors.
  3. Run half-inch PE for drip irrigation. Snake the tubing across the landscape to within a couple feet from the planting areas. Leave this tubing exposed until the plants are in place. Don't run half-inch tubing more than 200 feet or you will lose water pressure.
  4. If you need to connect multiple sections of tubing, you can use compression fittings.
  5. At the end of the tubing, attach a flush end cap. Be sure to mark the location of the end or put it in a small valve box for easy access later.
  6. After the plants are in place, attach microtubing and emitters to bring water to them.

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Irrigation clock
The irrigation clock tells the irrigation system when to come on and how long it should run. Most irrigation clocks are found in the garage, but they can be installed almost anywhere and come in both indoor and outdoor models.

Connect clock to valves
Using the trenches dug for your pipes and tubing, you will run wire from the clock to the valves. Irrigation wire comes with one white wire and multiple colored wires. The white wire is the common wire and attaches to every valve in your landscape. The colored wires are specific to each valve. Attach the colored wires to your clock in individually numbered terminals. After attaching, protect the connections with waterproof wire caps.

Emitters and microtubing
Microtubing and emitters connect to half-inch poly tubing and should be installed as instructed below:

  1. Run microtubing no longer than 15 feet.
  2. Attach an emitter to the end of the microtubing.

Place your emitters further apart if you have hard clay soil. Because water moves to the roots much slower in hard clay soil, a slow flow rate such as .5, 1 or 2 GPH should be used. Sandy soil is the opposite and emitters with higher flow rates should be used (4 GPH to 20 GPH)

Now is the time to decide if you want to place the emitters for each plant in anticipation of its future size or if you'll add emitters as the plant grows.

Backfill
Backfilling is the process of refilling all your trenches with soil again, covering all of your pipes, tubing and wires. Before you replace the dirt, screen the soil to remove large pieces. The dirt may contain rocks and other materials that can damage your tubing.

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