Trying to keep their lawn and garden beautiful under the hot summer sun, many Georgians are hauling out the hoses. But some get tired of constantly moving sprinklers.

Permanent irrigation systems allow easy, complete watering any time you choose. But there is more to installing a good system than just hiring it done.

"Get a plan," said Kerry Harrison, an engineer with the University of Georgia Extension Service. "Don't just go out there and start pointing and putting in sprinklers. And don't buy a system based completely on the cost."

Evelyn Sturgis, a Tift County homeowner, based her decision on expense and is sorry for it now. "Cost was a factor," she said, "and I think if we had it to do over, we wouldn't let that be top priority."

Harrison said a well-designed irrigation system will be expensive. "It's going to be more than you think it'll be," he said. "But that's what it takes to get an efficient, quality system that's installed correctly."

Thinking about installing permanent irrigation? Consider four points: design, quality of material, installation and management. Without any one of the four, Harrison said, the system can't be its most efficient.

No matter what system you choose, you have to manage it right.

"Excess water can cause disease and insect problems," Harrison said. "Too much is almost worse than not enough."

Georgia lawns require an inch to an inch-and-a-half of water every week. Harrison said watering half that amount twice a week provides the perfect amount of water for most lawns and gardens. It also allows nature to provide some water. Rainfall could save you both water and trouble.

"Of course as it heats up, lawns in full sun may need more than that," he said.

Harrison said the time when he sees the most sprinklers running - - daytime -- is actually the worst time to water.

"Night is best," he said. "From 9 p.m. to 9 a.m., you get the best water pressure and water supply. And you don't extend the wet period on the leaves."

Grass leaves that stay wet invite disease organisms to invade and cause problems.

Irrigation systems with timers offer solutions to many watering woes. But prepare for a bigger bill than you think.