One day after a water rationing plan took effect, decorative fountains fell idle, bar tabs grew and plumbing supply stores reported brisk sales of water-saving devices.

San Francisco residents have been told to cut consumption by 25 percent in response to the area's most severe water shortage since the 1976-77 drought. But many of the cutbacks will be highly visible to the hundreds of thousands of tourists who crowd the city each summer.Only fountains that use recycled water like the one in front of City Hall continued to flow Monday. Others were still filled with water but no longer sprayed it into the air or let it tumble from sculpted waterfalls.

Restaurants no longer serve water to diners automatically. Many, like Maxwell's Plum at Ghirardelli Square, have posted signs advising diners of the regulation.

"I would say right now, about one-quarter of the customers have asked for water," said dining director Robert Stewart as he observed the popular restaurant's luncheon crowd.

If one person at a table asks for water, only he gets water, said Stewart.

Business at the bar was up, Stewart said.

"At lunch, most people have a beverage. They have a drink, they have a little wine," he said. "The only people who might complain are usually from the Midwest. You know, they don't generally drink (alcohol) as much."

Homeowners were snatching up plumbing supplies such as sink washers and flow-restricting shower heads.

At the supermarket-like Goodman's Lumber store, plumbing manager Andy Pappas said he was especially busy Sunday afternoon as customers sought ways to cut water use in their homes.

He said people were especially interested in water-saving shower heads, which Goodman's stocks at prices ranging from $5 to $40. "The expensive ones have more adjustments for the spray," Pappas said.

"We carry a flow restrictor kit (for about $3), but it seems like they're more interested in putting on a new head," he said. "We're also selling a lot of washers."