If we care about plastic waste, why won't we stop drinking bottled water?

For all the innovation and choice that define the food and drink industries, if you want to make money, you could do a lot worse than fill a bottle with water and sell it. A litre of tap water, the stuff we have cleverly piped into our homes, costs less than half a penny. A litre of bottled water can cost well over a pound, especially for something fancy that has been sucked through a mountain.

Yet the bottled water market is livelier than ever. It defies our increasing awareness of the harm plastics do to the environment and a broader, growing sense that something has to change. Sales in the UK were worth a record £558.4 million this past year, an increase of 7%, according to the latest figures from the market analyst Kantar. Separate data from other analysts show that last year the British consumed more than 2.2 billion litres of bottled water, including "take-home" and "on-the-go" products. That's an annual rise in volume of 8.5%.

Environmental campaigners are struggling to understand why nations blessed with clean tap water grow only fonder of the bottle. "It's very surprising to me," says Sam Chetan-Walsh, a political adviser at Greenpeace and campaigner against ocean plastic. "Public awareness has never been higher, but the message is not quite reaching all the people it needs to." Where it is heard, the message is causing concern. Plastic water bottles require oceans of fossil fuels to make and ship. Additionally, single-use plastics of all types are polluting our cities and seas. Numerous documentaries have shown how plastic is ultimately killing wildlife.

Moves against various plastics have gathered pace, from shopping bags to straws and plastic-lined coffee cups. Chetan-Walsh argues that bottled water is different because the alternatives are so obvious. "If a product that is so nakedly unnecessary can exist, then the whole system is failing," he says.

Hope is not entirely out of reach. The rate of growth has begun to ease (sales were up 7% in the year, compared with 8% the previous year).

But even if large numbers of people are quitting bottled water because of care for the environment, others are taking it up. The introduction of the "sugar tax" on juices and soda drinks has pushed more people to bottled water, while health awareness has boosted its desirability. Tap water consumption is growing at roughly the same pace (UK consumers still drink almost three times as much tap water as bottled water).

So the plastic tide only creeps higher. The industry is quick to point out that all its bottles are recyclable. "But collection rates are, at the most generous estimates, 56%, so the actual recycling rate will be lower than that," Chetan-Walsh says. And while bottles may be recyclable, very few are made of recycled plastic. One water bottle company launched recycled half-litre "eco" bottles alongside its standard bottles. Another has pledged to use only recycled plastic across its range by 2025. Chetan-Walsh believes in a ban on single-use bottles. Bans do exist in some places. Organisers of a famous music festival announced that water bottles will not be sold this summer. San Francisco has banned them from city property and events. Last year, the UK government set out plans to ban single-use plastic from its estate.

Water bottlers, unsurprisingly, don't support bans. But they raise concerns about health rather than profit margins. Last month one chief executive of a water bottling company said that bans would "result in greater consumption of sugary drinks, adding to all the health dangers of obesity, diabetes and tooth decay". Kinvara Carey, general manager of an association of the biggest bottled water manufacturers, cites a survey in which people were asked what they would do if bottled water were not available. "Forty-four per cent would buy another drink, which is not great, 14% would go without and 4.5% said they would find a fountain," she says. "The choice is important."

What if fountains were more numerous, and tap water more clearly available in cafes, restaurants and elsewhere? Dozens of fountains are being installed in London. There are similar initiatives elsewhere. Before plastic and the marketing that made people think they needed bottled water in the first place, fountains were an urban fixture. Greenpeace, among others, is also pushing for a "deposit return" scheme. This would mean tax on bottled water would be refunded to customers who returned the plastic for recycling.

Even if bottled water sales are growing slightly more slowly, the industry is racing to adapt to changing concerns and tastes. Flavoured water is booming: sales of the sparkling variety shot up by 20%, according to the latest analyst data. Meanwhile, international water brands, as well as a range of new companies, are selling high-end reusable bottles. And if you must fill them with tap water, why not add flavouring?

As the owner of multiple sugary drink brands and bottled water, PepsiCo is facing challenges on health and environmental fronts. Last year, the company bought SodaStream (a drinks company that sells machines for making tap water bubbly and then consumers add flavours) for $3.2 billion. It also launched a range of fancy bottles that work with tap water and flavour packets. The bottle is reusable. The packets? Not so much, and, yes, they are made of plastic, although the company invites users to post them back for recycling.

As is so often the case, clever marketing can beat reason; awareness is rarely enough. "There is always this kind of slip between concern, intent and changed behaviour," says Giles Quick, an analyst of bottled water. "The best example is five a day, the recommendation to have at least five portions of fruit and vegetables every day. Almost everyone is aware of this, but something like 15% of us achieve it." Unless a far-reaching bottle ban does come into force, it will be up to consumers to not only demand change—but to act themselves.