How to Install a Sprinkler System

Before you start digging trenches and connecting the water supply you need to map out your plan in the garden. When doing this use flags to indicate sprinkler locations according to your design. Also, mark the location of your drip system risers, even if you plan to install the actual drip system at a later date, you can install your drip risers with the rest of your system. Use line marking spray paint to mark where you'll trench for pipes and wiring. Check to make sure you mark the lines accurately. You will be digging your trenches along these lines.

The plan of your sprinkler system should include the connection to the mains water supply and the location of the timer and valves, remembering that the timer and valves, if you need more than one zone, can be placed in the same box, if using a nine volt timer and solenoids, therefore making the need to run wires in trenches unnecessary. When laying out your irrigation lines, observe the following guidelines:-

1. Use as many straight runs as possible.

2. Try to avoid turns, which result in lots of pressure.

3. Avoid runs under sidewalks and driveways wherever possible.

4. Make 90 degree connections wherever possible.

The next step is to connect your water supply. Follow these instructions to get it connected:-

1. Shut off your water supply at the meter (you may want to check with your water department first).

2. Dig to expose the service line.

3. Tie into the service line, between the water meter and the house.

4. Remove a section of pipe, leaving a gap large enough to slide on a compression tee.

5. Slip the tee over each end of the pipe.

6. Tighten the compression nuts. The rubber gasket will compress against the pipe, creating a seal to prevent leakage.

7. Install a short nipple, using PTFE tape on all threaded connections to the tee.

8. Attach a shut-off valve, in a small enclosure, to this section of the pipe. The shut-off valve allows you to turn off the system by hand if necessary.

9. Keep this connection as clean as possible.

Next comes the trenching, both main and lateral line. The main irrigation line is the pipe that runs from your service line to your valve manifolds. The lateral lines are the lines that run from the valve manifolds to the sprinkler heads.

To soften the soil, water the ground approximately two days before you dig. Dig trenches 20cm to 30cm deep, ensuring you put turf to one side of the trench and soil on the other, making it easier to refill the trench when installation is complete.

Attach the main sprinkler line to the service line. Run it along the bottom of the trench from the house to the first set of valves, and if required, to the second set.

In-line valves are installed below ground and should always be installed in a protective valve box. Dig out the area where in-ground valves are to be installed and add several centimetres of gravel to the bottom of the hole. Place the top of the valve box so that it is even with the surface of the ground.

When you buy a valve box be sure to find out how many valves fit in each box so you know how many to buy. In some cases you will need more than one valve box per manifold.

If one of your valves will be used for drip irrigation, leave enough room between the valve and the sides of the valve box for the filter and pressure regulator that are part of your drip system. It maybe a good idea to install those parts on the valve, then, install the valve in the box.

To start laying the lateral pipes start from the valves and move outwards, laying the connecting pipe along the bottom of the trench. At each flag (remember your garden plan), install a tee or elbow fitting, and if needed, a riser for sprinkler attachment. Make sure you choose a pipe that gives you flexibility to adjust the sprinklers ensuring they are level with the soil.

After the pipes have been connected, turn on the water, open valves one zone at a time and flush until the water runs clear, Seal the fitting with duct tape to keep dirt out until the sprinklers have been installed. Don't backfill your trenches until your final system operation check is complete.

So now come the sprinklers. Remember to install one sprinkler zone at a time. Placing a sprinkler in a trench as a guide, measure from the connecting pipe fitting to the bottom of the sprinkler and cut a length of pipe you have chosen for the job. Place sprinklers at least 7.5cm from sidewalks and kerbs and 15cm from fences and buildings.

Install the appropriate elbow joint into the sprinkler and into the PVC or poly pipe fitting. Connect the pipe to the sprinkler and to the pipe fiting. Do not use more than 1m of pipe with each sprinkler head.

Position the sprinkler in the trench so that the top of the sprinkler is flush with ground level. Stabilise the sprinkler with soil without filling the entire trench. Verify that the sprinkler is vertical for optimum performance. Repeat the process for each sprinkler.

When installing your timer, as mentioned earlier, the best option is to use a 9 volt timer with 9 volt solenoids on the valves, meaning all these components can be placed in the same box, making the need to run any cables for your system unnecessary. Connect the valves to the timer using the valve wires using the following steps:-

1. Take one wire from each valve and connect them to a common wire.

2. At the timer, connect the common wire to the common terminal on the timer.

3. Take the other wire from each valve and connect them to the timer terminals in sequence.

Now all the hard work is done it's time to test your systems operation:-

1. Slowly turn on the water, then manually open an irrigation valve.

2. Adjust the sprinklers to ensure proper coverage

3. If you don't have complete head to head coverage make sure the control valve and shut-off valve are fully open and turn off any water being used in the house (washing machine, shower, taps etc). Then fine tune the sprinkler spray positions and spray patterns to match your coverage area. If the coverage is still not complete go back and check your system layout against your plan.

4. When you see that the coverage is satisfactory, fill in the trench.

That's it!! Your properly installed, automatic irrigation system will help keep your landscape green and healthy for years of recreation and enjoyment.