Sprinkler system cost

An in-ground sprinkler system costs $2,500 to $8,000 for a typical suburban lot, typically around $4,500. That works out at roughly $0.50 to $1.50 a square foot of irrigated area, or $700 to $1,500 per zone.

The number of zones is what drives the price, and the number of zones is decided by water pressure rather than by garden size.

What it costs

Zones are set by pressure, not by preference

Every sprinkler head needs a minimum flow and pressure to throw water the distance it is designed for. Your supply delivers a fixed number of gallons per minute at a given pressure.

Divide the available flow by what each head needs and you get the number of heads that can run at once. That is a zone. A garden needing thirty heads on a supply that runs six at a time is a five-zone system, and no amount of preference changes that.

This is why a designer should measure your static pressure and flow rate before quoting. A quote produced without those numbers is a guess, and the failure mode is a system that waters weakly and unevenly at the far end of every zone.

What a good design does

Head-to-head coverage. Each head's spray reaches the next head. It looks like over-watering on paper and it is what produces even coverage, because a sprinkler puts down far less water at the edge of its arc than near the head.

Zones grouped by need, not by geography. Lawn in full sun, lawn in shade, and beds all want different amounts. Putting them on one zone means over-watering one and under-watering another for the life of the system.

Drip for beds. Spray heads on planting beds waste water, wet the foliage and encourage disease. Drip line at $300 to $900 a zone is the correct answer.

Matched precipitation rates within a zone, so every head applies water at the same rate.

A rain sensor, which is required in many states and which is the difference between a system that waters in a downpour and one that does not.

Running cost, and whether it saves water

A sprinkler system does not save water by itself. A badly programmed one uses dramatically more than hand watering.

What genuinely reduces use:

• A smart controller using local weather data, which typically cuts consumption 20 to 50% against a fixed timer
• Watering deeply and infrequently, two or three times a week rather than daily, which drives roots down
• Watering before dawn, when evaporation and wind are lowest
• Checking the heads twice a season for ones spraying the pavement, which is the most common waste there is

Expect $30 to $150 a month in the growing season on a typical suburban lot, and much more in an arid climate. Some utilities offer a separate irrigation meter that avoids sewer charges on water that never enters the sewer, which pays back quickly where it is available.

Frequently asked questions

Do I need a backflow preventer?

Yes, essentially everywhere, and it is usually inspected. It stops irrigation water, which has been in contact with soil and fertiliser, being siphoned back into the drinking supply.

Can I install one myself?

It is done, and it is a large amount of trenching plus a design problem that needs pressure and flow calculations. The trenching machine and the design are the two reasons most people do not. Doing the trenching yourself and having it designed and connected professionally is a reasonable split.

What is winterisation and do I need it?

Blowing the water out of the lines with compressed air before the first freeze, $75 to $200. In any climate that freezes, yes: water left in a line splits the pipe and the heads, and the repair costs many times the service.

How long do the components last?

Pipe and fittings 20 to 40 years, heads 10 to 15, valves 10 to 20, controllers 10 to 15. Heads are consumables and are cheap to replace.

Does it add value to the house?

In hot and arid regions, meaningfully, because a green lawn is otherwise impractical. In a temperate climate it is a convenience rather than a value item, and buyers do not generally pay for it.