Reuters: The world’s top sellers of bottled water are trying to stop western consumers turning back to the tap by addressing environmental issues and trumpeting health benefits, while expanding aggressively in emerging markets. Nestle, the world’s biggest bottler of water with brands like Perrier and Poland Spring, said last week the economic slowdown and environmental concerns were hurting sales in western Europe and North America. PepsiCo saw double-digit declines in the third quarter …