Sprinkler Layout Basics: Head-to-Head Coverage, Hydrozones and Overspray

Sprinkler Layout Basics: Head-to-Head Coverage, Hydrozones and Overspray

A good sprinkler layout waters plants evenly and leaves the driveway dry. This guide covers layout ideas from the EPA WaterSense commercial irrigation guidance, which also applies to homes in principle. For zone counts and controllers see our article on sprinkler zones.

Head-to-head coverage

The EPA guide describes head-to-head coverage: each head is placed so that its spray arc just touches the head of each surrounding sprinkler. That overlap leaves no dry gaps. The guide gives no numeric spacing and tells designers to follow the manufacturer's recommended spacing for the head and nozzle you buy. When you replace a head, match the trajectory and keep head-to-head coverage.

Group by need (hydrozones)

Group plants with similar water needs, and account for soil, sun, shade, wind and slope. A shady bed and a sunny lawn should not share a valve.

Match the equipment

• Verify the system pressure falls within the manufacturer's specifications for the heads.
• The EPA suggests considering pressure-regulating heads with matched precipitation rates, or multi-trajectory rotating heads.
• Replacement equipment should be compatible with the existing equipment and from the same manufacturer.
• Fine-mist sprinklers are prone to wind drift, which wastes water.

Stop overspray

The guide says to water "the cultivated plants and not the pavement or other hardscape," and to design so that no water falls directly on impermeable or non-target areas.

Uniformity

The guide targets a distribution uniformity of at least 65 percent in design and audits, which it says the Irrigation Association rates as "very good" for fixed spray heads.

Water amounts

The EPA watering tips page says lawns and gardens need about one inch of water per week including rain, and describes a tuna can test to measure output. Local watering restrictions may apply. Not verified: your local rules.

Before you dig

Call your local utility-locate service before trenching. Not verified: the number and rules for your state.

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General information only. Not electrical, plumbing, legal or code advice. Confirm details with a licensed professional and your local authority.