New York There may be no such thing as a free lunch in this world. But New York Mayor Mike Bloomberg wants people to believe they can get a free treat in the city. It is easily accessible and flows from the taps of rich and poor alike - yes, he's talking about tap water. In 1,400 glossy ads on many subway cars and bus kiosks, the city is fighting back against the bottled-water industry. The stuff that comes out of the tap is given sex appeal. The ads show a glass of water with a slice of lemon on the brim and highlighting features such as zero sugar and zero calories - and it's free. They call on the public to 'Get Your Fill' and could easily be mistaken as ads for a high-end cocktail. 'If you can get people to drink a couple of glasses more of water and a couple of fewer of sweetened drinks, you could make a big difference in the biggest health threat that we see in this city today, and that's obesity,' Mr Bloomberg said. The mayor has the evidence he needs to justify the campaign. The quality of water in New York has long been among the top-ranked in the country. The city is one of the five municipalities in the country where filtration is not required because the water is so clean. And the Environmental Protection Agency considers water safe if fewer than 5 per cent of samples have live bacteria. New York City has kept its to 0.1 per cent and 0.2 per cent. And tap water may even be safer than bottled water because the quality of the latter, some of which comes from taps before being treated, is controlled by the US Food and Drug Administration, which has weaker standards. Water has been a controversial advertising topic in New York before. In 2003, filter manufacturer Brita ran ads in the city's subways to promote their products, claiming, 'It turns even New York tap water into drinking water'. The attack angered city officials, and the ads were pulled. But the image of tap water doesn't seem to have improved much since. 'I buy bottled water; tap water looks dirty,' said Yuri Moran, a native New Yorker. College student Paul Alexander said: 'I drink tap water sometimes. If I am thirsty, I can drink anything. But if I have a choice, I'll choose bottled water. It's safer.' The city's new campaign faces its greatest challenge in immigrant communities, with many people coming from countries where tap water is not to be trusted. 'I will never drink tap water. When I was a kid, my mum always told me not to or I'll get stomach ache,' said Ellen Bowman, an immigrant from Hong Kong. 'The campaign sounds like a big project, but that's not going to change me.' Some people also question the US$700,000 of taxpayers' money spent on the ads. 'That's a lot of money. It could have been used on something more meaningful, like collecting street garbage,' Ms Moran said. Still, Mel Peffers, a project manager of Environmental Defence, a non-profit organisation based in New York, said the campaign would reduce garbage if people consumed less bottled water. But she said it would have been better to use more memorable images, such as a combination of a pile of empty bottles and Mayor Bloomberg's smiling face while he enjoys a glass of the free treat. 'We need a better campaign to show our municipal system is safe, clean and reliable - even more reliable than bottled water,' Ms Peffers said. If there is one more thing that can be picked up from the campaign, it is not 100 per cent accurate. The water fees were raised 11.5 per cent from July 1, an average of US$72 more for every household each year. So it's not quite free anyway.