London's transport bosses are telling travellers on the tube system to beat the heat by carrying a bottle of water with them when they venture underground.

But how many of us are refilling our bottles with tap water rather than pouring money down the tube -- not to mention the cost of recycling the plastic bottles -- by buying a new bottle of water each day?

Cue the National Hydration Council whose eye-catching advertising campaign to encourage people to buy more "naturally sourced bottled water" -- on health grounds -- featured prominently on the underground network earlier this year.

The worrying thing for the bottled water lobby is not that people are doing what would appear to be the most sensible thing and refilling their bottles from the tap, but that Britons are replacing bottled water with sugary drinks instead.

We're told that sales of bottled water fell by 7 percent last year, with 71 percent of that decline the result of people buying sweet drinks instead. Good news for the soft drinks industry perhaps, but a worry for health officials.

Meanwhile, beneath the streets of London, the hot and flustered faces of fellow tube passengers shows just how dire it is on board the capital's underground trains when the mercury rises.

With a decent air-conditioning system on most lines a distant prospect, Transport for London (TfL) could show it cares by offering each of its cash-strapped passengers a free TfL water bottle and the opportunity to refill them at its stations.

"Sparkling or still?"
 
Remember when that question, asked with a certain downward gaze, would make you feel like a tactless tightwad for requesting tap? Did you try to lessen the shame with a smile and a clever nickname, like "I'll have 'New York's Finest'"?
 
Restaurants and hotels across the country are blurring the lines between these choices, as they stop serving bottled water due to a perception that it is environmentally unfriendly. Critics object to the waste left behind by the plastic and glass bottles, as well as the fuel and other natural resources used to manufacture and ship the bottles all over the world.
 
"In the world of trying to live in a more green, sustainable environment, I think water is the most obvious, simple thing that we can do," said Joseph Bastianich, a business partner of Mario Batali and co-owner of restaurants including Babbo, Lupa, Esca and Del Posto.
 
Bastianich told Reuters he is in the process of phasing out water across all his restaurants, following in the footsteps of other environmentally-conscious restaurants like Alice Waters' Chez Panisse in Berkeley, California.
 
In its place, Bastianich is installing filters made by Natura Water, which purify a restaurant's tap water and allow users to get still, sparkling or room temperature tap water. The restaurants can adjust the amount of carbonation, allowing them to tout the water as made in-house.
 
The Natura system, which comes with reusable water bottles for serving, can be rented for about $400 a month. 
 
Company founder Marco De Plano, whose customers also include L.A.'s  Ciudad, San Francisco's Foreign Cinema and certain Four Seasons hotels, said that with prices of high-end bottled water bubbling as high as $10, high-traffic locations can recoup their losses quickly.
 
"When we started this a year ago, everybody was talking about the green aspect," De Plano said. 
 
Bastianich says a liter of Natura water costs him about 50 cents and sells for about $4. That profit margin is slimmer than before, when he would pay about 80 cents for a liter of premium bottled mineral water and sell it for up to $9. 
 
"We think the loss of margin is an investment that's very worthwhile making," Bastianich said. 

The sacrifice to margins would lessen as sales of house-made water increase.

As the backlash against bottled water heats up across the country a host of local governments have cut bottled water out of their budgets.  Virginia, Illinois and New York are among the states that have banned buying bottled water with state funds.

(Photos: Reuters\Eric Thayer)

If you’re tired of feeling guilty about driving a gas-guzzling car or cranking up your air conditioning, you could just try hanging your head in shame about that bottle of spring water you are sipping instead.

Yes, the foes of bottled water are at it again, this time in the form of an advertising campaign that aims to promote tap water and underscore the environmental costs of producing and disposing of plastic water bottles.

Tappening, a group that opposes bottled water, is spending $250,000 on a media campaign to promote its cause. Tappening is a joint venture of ad agency DiMassimo Goldstein and public relations firm Ericho Communications. It most recently launched a campaign called “Message in a Bottle” that aims to deliver one million empty water bottles to incoming Coca-Cola CEO Muhter Kent.

The campaign is the latest of many recent attacks on bottled water, including the urging of boycotts by the mayors of cities including London, San Francisco and Seattle.

“We can use our advertising and public relations abilities to un-sell bottled water hype,” said Tappening’s Mark DiMassimo.

The ads will appear as “wild postings” on construction sites in ten U.S. cities as well as in magazines and community newspapers, the group said. The ads claim that last year, plastic bottles generated more than 2.5 million tons of carbon dioxide and that every year, 38 million bottles end up buried in the ground.