Step Five: Install Irrigation Materials
The general instructions provided in this guide are for systems and components commonly used in residential landscapes, but do not necessarily apply to all types of systems and components. Read and follow any instructions that come with your irrigation system components and contact your salesperson if you need advice. Construction drawings for the major irrigation system components shown below serve as a guide during the installation process.
1Purchasing and Preparation
Review your irrigation system plan thoroughly to get reacquainted with the plan and its components.
- Also, reread the section of this guide that pertains to developing an irrigation system plan. A short refresher course now may save time and effort later.
- Take your plan to an irrigation supply store and ask for help with selecting the equipment. Take this guide along to show them the construction details for the backflow preventer and irrigation valves.
- If possible, purchase all of the irrigation system components at the same time. Don't forget smaller items like pipe cutters, TeflonTM tape, primer, glue and temporary marking paint.
- Buy extra irrigation line and fittings to handle unexpected problems.
- Before digging, mark the locations of all irrigation lines and valves with temporary marking paint. This will provide a visual layout for the work ahead.
- Now is the time to make any changes to your irrigation system design to properly route the irrigation lines. If you do make changes, revise your irrigation plan accordingly.
2Install Backflow Prevention Assembly
Backflow prevention assemblies are required for all irrigation systems regardless of size. The purpose of these devices is to prevent contaminated water from getting into the drinking water system.
If you need to install a backflow preventer, it is necessary to obtain a plumbing permit and follow all city code requirements. If you haven't done so already, call your city for permit information.
To ensure proper installation that will pass a city inspection, it is recommended that you hire a contractor to install this irrigation system component.
Below are some guidelines that your contractor should follow during the installation process.
Guidelines for Contractors
- Backflow preventer assemblies are typically installed near the water source at least twelve inches above the highest downstream water outlet. There are many types of backflow preventers available. The Uniform Plumbing Code (UPC) has specific installation requirements depending on type.
- Pressure vacuum breakers (PVBs) or reduced pressure assemblies (RPs) are recommended since one assembly can serve multiple valves. Although atmospheric vacuum breakers (AVBs) are easier to install, they cannot be tested to see if they are functioning properly. In addition, an AVB is required for every control valve.
- Type K copper pipe should be used for all above ground piping and requires a torch and non-lead solder to connect the copper fittings.
- A ball valve should be installed on the riser going to the backflow preventer to shut off the water during emergencies or repairs available. Don't forget, the UPC has specific installation requirements depending on type.
- At least one union should be installed within one foot of the backflow prevention assembly for ease of repair or replacement. However, two unions are preferable, with one upstream and one downstream of the assembly.
- With a PVB or RP, the irrigation valves must be installed downstream of the assembly. However, the AVB must have the valve installed upstream of the assembly, therefore requiring a dedicated AVB for each irrigation valve installed.
- If your home already has a front yard landscape with a backflow preventer, it is fairly easy to extend additional valves from the front yard to the back yard. If you extend the existing system, follow the rules specified in the UPC.
3Install the Valves, Filter, Pressure Regulator, and Valve Box
The valve, filter and pressure regulator are typically located inside a valve box that is usually placed near the backflow preventer.
- Do not put too many valves in one valve box. Two valves per box is recommended. Leave enough room in each valve box to allow yourself to work comfortably with the valves and wires and to easily remove and replace the filter later on during routine maintenance.
- For aesthetic and practical reasons, it is better to place valve boxes below ground, making the top of each valve box about two inches above grade (this will put valve boxes at ground level after the top dressing has been installed).
- After determining the best place for the valve box, dig out the area adequately so that the top of the valve box will rest at grade (it will be raised above grade later on during the installation process).
- Because the system will experience higher pressure before the valve, schedule 40 PVC pipe should be used between a PVB or RP backflow preventer assembly and the valve.
- After the control valves are installed, attach a filter and a pressure regulator to each one.
- Wrap a small amount of Teflon tape around all threaded fittings to help lubricate and seal them. Make sure all fittings are good and tight.
- With the valves installed, it is now time to place the box over the valves. You may have to cut additional holes in the sides of each box to allow for proper location of the pipe/poly tubing.
- Place bricks or blocks strategically under the edges of each box to provide stability. This should raise your box two inches above grade.
- Be sure the box is level; then replace soil around the outside edges of the box. Cover excess openings around pipes with fabric or tape to keep soil from entering the box.
- Fill the bottom of each valve box with one to two inches of gravel to promote drainage and to avoid muddy conditions inside the box.
4Dig the Trench
If you haven't done so already, mark the location of all trenches with temporary marking paint.
- About two days in advance, soak areas to be trenched with water. This will make digging a lot easier.
- Dig the trenches six to eight inches deep, rounding corners to prevent the poly tubing from kinking during installation.
- You can use a common trench for pipe/poly tubing connecting to different valves and wiring for low-voltage outdoor lighting. Make sure the wiring (if in the same trench) is to the side or under the pipe/tubing so it doesn’t get damaged if repairs are needed in the future.
If you are using PVC pipe, make sure the pipe and fittings are clean.
- Then apply a light, even coat of primer and glue to both the pipe and the fitting. After connecting the pipe and fitting, wipe off any excess glue. Allow the glue to set for twenty-four hours before pressure testing for leaks.
- Poly tubing has a tendency to roll back on itself. If you are using poly tubing rather than pipe, allow the tubing to warm in the sun. It will become softer and easier to work with. To hold the tubing in place, put some soil back in the trench (spot backfilling) about every five feet.
- If a common trench is used, consider painting each pipe or poly line a different color to identify the type of plant or planting area each line waters. Colors should correspond with those used on your irrigation plan.
- Leave fittings exposed so they can be pressure tested for leaks.
- Flush the lines before installing emitters.
- Open one flush cap at a time and let each valve run for about two minutes.
- Do not exceed 200 feet of poly tubing from the valve to the flush cap.
- Do not exceed a total flow of 200 gallons per hour (gph) per valve.
- Micro tubing that exceeds six feet in length is NOT recommended.
Install Emitters and Micro tubing
- Install micro tubing and emitters prior to planting so water is available immediately after plants are installed.
- Use self-piercing emitters or a hole punch that is the proper size for the emitter. Your irrigation supplier can help you choose the proper hole punch. If you make a mistake, use a goof plug to seal the hole.
- After installing emitters and micro tubing, spot backfill to keep them in place.
- Emitter tubing outlets should be placed between one and three inches above the ground. Proper placement will allow you to observe the wetting pattern for each plant and will reduce the likelihood that dirt from the surrounding area will clog the tubing.
- Emitters can be placed directly into the poly tubing or anywhere along the micro tubing as long as the tubing outlets are above ground.
- Above-ground emitters are easier to maintain, whereas underground emitters cannot be chewed by rodents.
6Install the Irrigation Controller (Automatic Timer)
Indoor controllers plug into electrical outlets whereas outdoor controllers have wires that run directly to the breaker box.
- Do NOT mount indoor controllers outside.
- If possible, mount the controller in a shady location.
- Danger: There is live voltage electricity in the circuit breaker box. All 110-volt electrical work must be done by a licensed electrician. A permit may be required by your city.
- It is recommended that you connect the controller to its own dedicated breaker. Do not connect the controller to a GFI (ground fault interrupt) circuit.
- Irrigation controllers must be properly grounded. Follow the manufacturer's instructions carefully.
- Use "direct burial wires" or an irrigation controller cable. The cable has color coded wires to make it easy to match the valves to the proper stations in the controller. For most residential irrigation systems, 18-gauge wire is acceptable.
- Wire expands and contracts with changes in weather. Leave some slack in the wire when running it from the controller to the valves. It also is a good idea to coil some wire at the end of each connection to give you ample wire to work with in the future, when it's time for maintenance or repairs.
- Connect the wire to the valves with waterproof connectors.
- If wire is being placed in the same trench with the irrigation lines, protect it from damage during installation and future repairs by tucking it under the lines.
7Take Photos and Update the Irrigation System Plan
Before backfilling the irrigation lines, photograph each section of the yard. Begin at one end and work in strips, either lengthwise or vertically.
- Label the photos to correspond with the sequence you chose and keep them with your irrigation system plan. These photographs will help to verify the exact location of your irrigation system components when it is time to make repairs.
- If you installed trenches or other system components differently than what appears on the irrigation system plan, revise the plan to show the actual location of each line. This updated "as built" plan can save time and labor in the future.
8Inspect the System and Backfill
Before backfilling, turn on the irrigation system and inspect it for leaks.
- Check to see if each emitter is operating properly.
- Make any necessary repairs, then run the system again as a final check.
- Prior to backfilling, remove rocks and other debris from the surrounding soil. These might damage the pipe/poly tubing.
- Backfill the trench halfway, lightly tamping the soil with your foot. Then fill it with water to settle the soil.
- Backfill the remainder of the soil. Then water again.