How To: Install Irrigation Supply Lines

Installing irrigation piping is simple to do yourself. But if you go about it the wrong way, you can find yourself taking much longer than you needed to & making a mess, follow these steps to knock it over with the minimum of fuss.

Have a Game Plan

Using your irrigation plan, work out where you’re digging first. Then, pick up the shovel as little as you can. The things you want to avoid: digging trenches you don’t end up using & un-backfilling. Try these tips:

  1. Pre-mark your trenches: With Marking Spray Paint as a guide.

  2. Do all of your digging in one hit: Avoid laying pipe as you go. Putting down the shovel, grabbing pipe, glue, cutters is not only just tiring to say, it’s inefficient & makes it easy for dirt to get in the pipe which you really want to avoid.

  3. Work from the Water Supply: In case you come across a hidden obstacle, then you can easily adjust.

  4. Don’t be too eager to backfill: Make sure you don’t need to run any more pipe in a trench before you backfill, think about whether you can lay a lateral line in the same trench.

Trenching Existing Lawns

No one wants to end up with lumpy, or worse dead, lines of lawn that follow where you’ve been digging. So follow these steps:

  1. Using a Flat Shovel, cut into the turf at a 45 degree angle down one edge of your trench. Then do the same on the other side, with about 20cm spacing wchich will be the width of your trench.

  2. At 30cm intervals, use the shovel to cut up the turf into wedges which you can then easily lift out and place 30cm to the side of the trench. Try and keep them in their same line for easy repositioning.

  3. Using a Trenching Shovel, dig out trench to a depth of about 15-20cm. If a large amount of digging is required, trenching machines are available for hire from most hire centres.

  4. Lay Pipe

  5. Backfill trenches with a Flat Shovel & Outdoor Broom to get as much as you can & place turf wedges back in the trench.

  6. The wedges will stick up from the level of the lawn, so using a flattening or stamping tool hit down the turf until as close to level as possible. If you can’t get it to exactly level, that’s ok, it the dirt should settle & level out over the coming days with watering.

Getting Under Paths

Boring under paths is often the most difficult part of running your irrigation lines. In an ideal situation, lifting pavers to uncover loose soil for an easy dug trench is the way to go, but often it’s not. So the only way to go is underneath either with Water or Dry Boring. There’s no art to getting pipe under path, it’s just any way possible.

Water Boring

Uses water erosion and forearms, it’s messy, but gets the job done.

  1. Cut a piece of PVC Pipe to just longer than the width of your path. The PVC pipe should either be big enough to fit the poly pipe you’re running, or the right size for you to use once it’s in position.

  2. Attach a hose to the end using a Click-On Hose Fitting & a PVC Valve Socket.

  3. Dig a Trench perpendicular to your path at the depth your pipe will bore under the path & at the length. The pipe needs to bore in level otherwise you won’t find it on the other side!

  4. Dig a hole on the other side of the path to where you anticipate the pipe to appear, give yourself a little extra depth & width just incase the pipe diverts off course a little.

  5. Turn the tap on & use all of your strength to push the pipe through.

Dry Boring:

Dry boring requires the same preparation of the area, but by swapping a couple of tools, you can get through some pretty tough ground.

  1. Dig a Trench like above, perpendicular to & just longer than the width of the path.

  2. Dig a hole on the other side like above.

  3. With a Brass Arrow Headed Fitting (sometimes called a Channel Bob) attached to a Galvanised Steel Pole, use a sledgehammer & ram the pole underneath the path.

  4. Remove the pole & replace with PVC Pipe once through.

Laying Pipe

Laying pipe is easy, but like anything, it can be more of a hassle than it needs to be. So follow these steps:

  1. Install in the direction of flow: If you’re doing a main line, start at the water connection. And for the zones, start at the valves. It’s far easier to add pipelines, than it is to join 2 together, so work in one direction.

  2. Don’t Backfill until you’ve finished laying your Pipe: Backfilling as you go is inefficient & makes it harder to make small adjustments further down the line.

  3. If laying PVC:

    1. Use Primer on Main Lines: This cleans the pipe surface so the glue fully cures and holds mains pressure.

    2. File off Burrs: After PVC is cut, the edge is often rough or raised, file it down with the back of your blade for a smooth seal.

    3. Avoid Over Gluing: PVC solvents effectively burn the pipe to join them, over gluing is not only messy, it can damage the pipe & cause bursting.

  4. If laying Poly:

    1. Lay pipe out on it’s back: Don’t be tempted to dump your coil & just pull rings off, lay the pipe out on it’s back so it lays down nicely in your trenches & is easy to work with.

    2. Don’t forget Clamps: This isn't just about forgetting to buy clamps, make sure there’s one on every join. Because if you miss one, pop!

  5. Cover open ends with Tape: You don’t want your pipe filling with dirt or you could find yourself damaging valves or other components, so if you’ve got an bit of pipe you’re not finished with, cover it with tape & come back to it.

  6. Flush Out Lines: Just in case some dirt does get in the line during installation. Before you seal everything off, leave one end open & run your system for 5 or so seconds to flush anything out, then cap it off & you’re good to go!


PDF Download: HowToInstallIrrigationSupplyLines.pdf