Here's an ad we'd like to see in neon lights near the entrance to a Concord restaurant or bar. It would portray Long Pond from Little Pond Road or the heights above. The trees ringing the pond would be crystalline with ice from a freezing rain. Above them would appear the words "On Tap Here."

Concord's water, save on days when line maintenance turns it an unappealing orange, is by and large excellent. That makes bottled water a convenience or a luxury.

The $11 billion or so Americans shell out for bottled water is, for the most part, a waste of money and a needless burden on the environment. The bottles, after all, are made from crude oil, and more oil is burned hauling billions of bottles of water from here to there. Most of them, since relatively few of the ubiquitous bottles are recycled, are sent to landfills and incinerators.

Trend spotters have noticed that, here and there, from New York to California, upscale restaurants are switching back from bottled water to tap. They include Chez Panisse in Berkeley, Nopa in San Francisco and Del Posto in New York. And some mayors and city officials are cutting bottled water from the budget and telling employees to turn on the tap. It's a trend that deserves to spread.

The switch can't be done without repercussions for a restaurant's bottom line. The profit margin on bottled water is one of the biggest in the restaurant industry. Nor will customers trained to believe that bottled water is purer, safer or simply cool, always be content with water by the glass, even if it's free. Many bottled water companies, including some of the biggest, just fill their bottles with filtered tap water anyway.

To their credit, many area eateries never stopped filling the water glasses on the table. They bring bottled water only when a customer requests it. That's the way it should be. Some restaurants filter the tap water to polish it and remove the chlorine - plenty of people do that at home too - or carbonate it on the spot to add sparkle. But it's still locally-produced tap water, piped not trucked, and it costs a fraction of a cent per glass.

Recently, New York city officials calculated that someone who drinks the equivalent of eight glasses of water per day from disposable bottles would spend about $1,400 per year. That's the equivalent of cross-country airfare for two. So save bottled water for emergencies.

You'll be doing your wallet and the planet a favor.