One of the state's leading environmentalist called Friday for permanent outdoor watering restrictions during daylight hours, and metro Atlanta's environmental planner agreed.

Sally Bethea, executive director of the Upper Chattahoochee Riverkeeper, an environmental advocacy group, said the region should ban daylight lawn and garden sprinkling even after the current drought eases.

"They do it in Austin and Jacksonville," Bethea said.

She added that permanent, clearly defined rules would be easier to follow than the changing chessboard of state regulations overlaid with different local requirements.

"I keep getting confused as to when I can or can't water," she said.

As much as 50 percent of the water used during the heat of the day is lost to evaporation. Current state rules limit most outdoor watering to the hours from midnight to 10 a.m. In metro Atlanta, only hand-held garden hoses can be used for 25 minutes on a three-day-a-week schedule based on street address.

Bethea made her comments in Midtown Atlanta at the monthly Sustainable Atlanta Roundtable meeting hosted by Southface, which promotes sustainable development. The topic was water conservation.

During the question and answer period, the Atlanta Regional Commission's environmental planning chief, Pat Stevens, said "I like the idea of some permanent outdoor restrictions."

State restrictions already limit home and business owners to watering their landscapes to three days a week. The Board of Natural Resources adopted the rule in 2003 and left enforcement up to each individual water provider, usually city and county governments.

Before the drought, enforcement was typically lax.

The state schedule for watering is: odd-numbered addresses may water on Tuesdays, Thursdays and Sundays; even-numbered and unnumbered addresses may water on Mondays, Wednesdays and Saturdays. No one can water on Fridays.

When there is not a drought, home and business owners can water as long as they want at any time.

Bethea listed two other must-dos for metro Atlanta to avoid running out of drinking water in the future. Fix leaky underground pipes that carry treated drinking water to individual buildings, and replace old toilets with new, low-flow toilets that can save as much as 5 gallons a flush.

"To avoid the collision course we are most assuredly on. . . we've got to take smart and really aggressive action now because we're nearly tapped out," Bethea said.