The zeitgeist has been turning against bottled water for some time now. Mayors in San Francisco, Los Angeles, Minneapolis, and other cities ruled that their local governments would no longer spend taxpayer money on the stuff; restaurateur Alice Waters of Berkeley?s famed Chez Panisse struck it from the menu; and The New York Times published two widely read articles — an editorial titled “In Praise of Tap Water” and a style piece, “Water, Water Everywhere but Guilt by the Bottleful” — within days of each other last summer. The moment is ripe for Elizabeth Royte?s Bottlemania, an admirable, engaging book that examines the social, economic, and environmental impact of bottled water, whose sales now surpass those of beer and milk in the United States.

The heart of Bottlemania is the fascinating fight over water that has polarized the tiny town of Fryeburg, Maine. Fryeburg sits upon one of the aquifers whose water is sold as Poland Spring. While Poland Spring water was being peddled as early as 1845, the company was bought in 1992 by Nestlé, which has gobbled up a number of other brands nationwide — Deer Park, Zephyrhills, Calistoga, and Ice Mountain among them — and which has an economic stake in carting off as much of Fryeburg?s water as it can get away with.

But does Nestlé?s seemingly unquenchable thirst — the Poland Spring bottling plant in Hollis, Maine, “fills between 5 and 6 million bottles a day, 358 days a year,” Royte reports — benefit anyone other than the corporation? One of the issues is economic: the Fryeburg utility sells the water to a middleman, a local company called Pure Mountain Springs, for less than a penny a gallon; Pure Mountain turns around and sells it to Nestlé for four cents a gallon more.

So the very same water that locals get pumped into their taps is enriching a handful of residents but doing nothing for Fryeburg?s long-term economic development. (New York City, by comparison, consumes vast amounts of water drawn from upstate reservoirs, but the city pays more than $100 million in annual property taxes to watershed towns.) Even more galling to Fryeburg activists is the fact that the deal wasn?t subject to public scrutiny. Such an arrangement wouldn?t fly in every state, but Nestlé has benefited from Maine?s weak water protection laws.

In addition to the question of fairness are pressing environmental concerns. One has to do with truck traffic and its attendant pollution: a citizen?s group in a Maine community between Fryeburg and Hollis counted 92 tanker trunks barreling through their town in 24 hours. Another has to do with the pumping?s effects on the ecosystem. While the vast majority of the area?s groundwater is consumed by local residents, not by bottled-water drinkers, residents discharge their water back into the same watershed. “Every gallon of water that thunders into a tanker truck represents a measure that doesn?t seep through the aquifer and into wetlands, another gallon that isn?t diluting the pollutants that run into the Saco from roads, farms, septic tanks, and industry,” Royte explains.

A third environmental concern is the one that has gotten the most play in the current anti-bottle backlash: bottled water?s contribution to global warming. According to Royte, it takes 17 million barrels of oil a year to produce water bottles for the U.S. market; substantially more energy is required to fill those bottles and transport them to consumers. Moreover, a mere 15 percent of water bottles are recycled, as most are polished off in places that lack recycling bins.

Royte relates this information with intelligence and wit, and with no pretense of objectivity: she is a tap-water enthusiast who practically recoils when the Poland Spring reps she interviews offer her samples of their product. Part of me wishes Royte had ended the book with her cogent critique of bottled water, allowing concerned readers to cut down or break their habit and feel fairly good about themselves.

But instead, the intrepid journalist, who trained her investigative eye on our trash in a previous book, Garbage Land, decides that understanding the bottled-water boom requires a look at the state of the nation?s tap water. It is, of course, a relevant question: if tap is in as good shape as we?ve been told, why are so many of us shelling out money for water?

Royte takes an informal poll, asking friends where their tap water comes from. “Most people,” she reports, “even those who knew exactly how many miles the arugula on their plate had traveled, had no idea.” Her ensuing explanation is interesting and informative, if unsettling. Tap water comes either from groundwater (which begins as snow or rain) or surface water (which is pulled from lakes or rivers). Whichever the case, it is then generally dosed with chlorine or some other disinfectant, filtered, and piped into taps.

While the tap water available to the vast majority of Americans meets or exceeds the standards set by the Environmental Protection Agency, one of the disquieting studies Royte cites concluded that tap water in 41 states contained 141 chemicals — from industry, agriculture, development, and, get this, from water treatment itself — for which the government hasn?t set safety standards. “It?s enough to make a tap lover cry,” she writes ruefully. She describes how overdevelopment has increased erosion and how erosion has increased the levels of sediment in our reservoirs — sediment that can prevent chlorine from doing its job and can serve as sustenance for disease-causing organisms. Meanwhile, the alum used to sink the sediment particles carries its own risks, and the rise in the use of ethanol, a fuel intended to help clean our air, has an effect on water that reeks of irony: the increased amount of corn planted to create ethanol has resulted in the increased use of the dangerous fertilizer atrazine, which seeps into water supplies following heavy rains. And on and on it goes.

Despite these findings, at the end of the book Royte is pretty much where she started: she has ditched her plastic refillable bottle for an aluminum one (“so far unindicted by the chemical police”), but she?s sticking with tap, and she urges readers to do the same. “It?s a self-fulfilling prophecy,” she writes. “The fewer who drink from public supplies, the worse the water will get, and the more bottled water we?ll need.” (Her section on Coca-Cola and Pepsi, whose Dasani and Aquafina brands are simply municipal water subjected to an intense filtration process, includes a sinister quotation from Pepsi executive Susan Wellington: “When we?re done, tap water will be relegated to showers and washing dishes.” You can almost hear thunderclaps and cackling.)

Royte gamely concludes on an upbeat note, revisiting Fryeburg and reporting that despite Nestlé?s startling purchase of Pure Mountain Springs, the middleman company, there is some good news: the corporation has agreed to submit to stricter environmental monitoring, and the town has defeated an ordinance that would have allowed Nestlé to buy unlimited water from the aquifer. Royte also provides conservation-minded steps readers can take to protect water supplies. Still, her lucid critique of bottled water combined with her disturbing discoveries about tap may leave readers feeling thirsty for a third option.