How to install a garden sprinkler system yourself

Dragging a hose around the yard is the sort of job that only takes 20 minutes, which is exactly why it quietly eats an hour of every week and nobody ever costs it. A sprinkler system off the garden tap is a weekend of work and a few fittings, and after that the watering happens at 6am whether you are awake or not.

It is not a hard job. What it is, is a job where two decisions up front settle whether the thing works properly or disappoints you for the next 10 years, and they are the two that most instructions skip over.

Before anything else, sort out backflow

Water that has been sitting in a buried line among the soil and the mulch is not water you want pulled back into the house supply, and that is exactly what can happen when the mains pressure drops while your system is running. Anything connected to a drinking water tap needs a backflow prevention device on it, which for a domestic garden system usually means a dual check valve or a non return valve fitted at the tap. If you are having the system plumbed in permanently rather than run off a hose fitting, that part is a licensed plumber's job and not a DIY one.

Find out where your services run before you put a spade in the ground as well. Water, gas, power and phone all get buried in a front yard and none of them sit where you would assume.

Measure your flow before you buy a single head

This is the decision that sinks most home systems, because people fit eight sprinklers to one line, turn it on, and get eight sad dribbles instead of four proper sprays.

Put a 9 litre bucket under the garden tap, turn it full on, and time how long it takes to fill. Divide 9 by the number of seconds and multiply by 60, and that is your flow in litres per minute. A typical suburban tap gives you somewhere in the high teens to mid twenties, and you want to work to about 75% of it rather than the whole lot.

Then add up the flow rating printed on the packet of every head you want running at once. If the total goes over that 75% figure, split the yard into two or three zones and run them one at a time on separate lines, or put in a timer with more than one outlet. Fewer heads doing the job properly beats more heads doing it badly, every single time.

What you need

  • Low density poly pipe, 13mm for a small run and 19mm once the yard gets bigger
  • Barbed fittings, elbows and tees to suit the pipe size you picked
  • Sprinkler heads, pop up for lawn and fixed on risers for garden beds
  • Poly risers, so a bed sprinkler clears the plants rather than spraying into them
  • An inline filter, which is 5 minutes of work that saves you clearing blocked nozzles later
  • A tap timer, mechanical if you want it simple and digital if you want more than one start time

Setting it out

Sketch the yard and mark where the water has to reach, then place the heads so their spray patterns overlap. Overlap is not waste. A spray head puts down much less water at the far edge of its throw than it does close in, so a pattern that only just touches its neighbour leaves a dry ring around every head, and that is the mysterious brown patch people spend a summer feeding and watering for no result.

Keep pop up heads in from the edges of paths by about 100mm so the mower and the edger miss them, and keep them out of the line you walk on.

Depth, and why the shallow advice is wrong

Plenty of guides tell you a shallow trench is fine. It is fine right up until the first time somebody puts a garden fork through the lawn or runs a corer over it. Under a garden bed, 100mm of cover is enough. Under lawn, go 200mm to 300mm, because that is the difference between a system you forget about and a repair every time anybody does anything to the grass.

Lay the pipe out in the sun for an hour before you start joining it, because warm poly goes onto a barbed fitting easily and cold poly fights you the whole way.

Flush it, test it, then bury it

With the pipe joined and the heads not yet fitted, run the water through for a minute to push out the dirt and the shavings that got in while you were cutting. Then fit the heads, turn it on, and walk the yard looking for leaks at the joins and for heads that are spraying the fence or the driveway instead of the lawn.

Only backfill once you are happy. Covering a trench and then finding the fault is the sort of afternoon that turns a good job into a bad memory.

Four mistakes worth not making

  • Putting pop up sprays and drip line on the same station. They want different run times and different pressures, so one of them always ends up wrong. Run them separately.
  • Skipping the filter. Our water carries enough grit to block a nozzle, and clearing them one at a time in January is nobody's idea of a good time.
  • Setting the timer for the evening. Water sitting on leaves and soil overnight is what fungal disease wants. Set it for first light instead.
  • Watering little and often. A short daily sprinkle keeps the roots up near the surface where they cook. A longer soak every few days sends them down.

Take the sketch and your flow figure in with you and we can work out the head count and the fittings over the counter, which is a lot quicker than standing in the aisle guessing at it.

Shop related products

Did you know we also stock low density poly pipe in 13mm, 19mm and 25mm on 25 metre rolls, 50mm pop up sprinklers in full, half, three quarter and centre strip patterns, poly risers from 150mm up to 930mm, inline filters in 13mm and 19mm, impact and oscillating heads, non return valves and a long row of barbed fittings. Almost none of that is on the website, so give us a ring on (08) 8536 4333 to check what is on the shelf.

The watering gear sits in the garden centre alongside the Pope range, and if you are picking up a few rolls of pipe we run a local delivery service on Tuesdays and Thursdays.

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