Common sense, born in Europe, is gradually taking hold right here in the U.S.A.

For years, Europe's consumer-goods titans have pushed the eminently sensible idea of selling concentrated detergent, rather than the bigger, more diluted versions we mainly see on the shelves of U.S. supermarkets. Last year, America's Procter & Gamble (NYSE:PG) joined Unilever (NYSE:UL) in selling concentrated bottles of detergent at Wal-Mart (NYSE:WMT) stores in the U.S. This morning, Wal-Mart announced that it's taking the next logical step down the continuum -- promising to sell only concentrated liquid laundry detergents in the U.S. According to the retail giant, the switch will save 95 million pounds of plastic resin, more than 125 million pounds of cardboard, and 400 million gallons of water.

It's a decision calculated to satisfy the "Greens," but they shouldn't be the only ones cheering. Wal-Mart shareholders can expect their firm to save an unspecified, but presumably significant amount on the cost of packaging all that watered-down detergent, not to mention the cost of lugging it around the country on fossil fuel-burning trucks. And the PR value? Priceless.

This is an unqualified win for Wal-Mart. Sears (NASDAQ:SHLD), Costco (NASDAQ:COST), and Target (NYSE:TGT)? The bottle's in your court now.

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