Water supply piping -- usually polyvinyl chloride (PVC) -- routes water underground from the main supply pipe to valves and then to sprinkler heads. Valves control the flow to the heads; these may be operated manually or by an electric timer. An antisiphon device on the valves prevents any backflow of tainted water to the water supply system. Sprinkler heads deliver the water to the yard.

Two main types of sprinkler heads are available: spray and rotary. Spray heads are preferred for tightly controlled watering of shrubs and irregular areas; rotary heads require higher water pressure and work better for expansive lawns and densely planted areas because they throw water further, up to about 90 feet.

Pop-up heads automatically rise up when the water surges through them, then lower when the water shuts off. These are used where there is considerable foot traffic or on open lawns. Sprinkler heads come in a wide assortment, each designed to emit a different amount or pattern of spray. Spray patterns include quarter circle, half circle, three-quarter circle, full circle, and rectangular strip patterns. A sprinkler's output is measured by its flow rate, the gallons of water it delivers in a minute (gpm).

Copyright Don Vandervort, Hometips.com

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