In the great global rush for bottled water, nowhere is thirstier than Asia. Demand is predicted to surge by more than 140% across the region this decade, to account for one-third of the global total by 2020.

China leads the way. The country accounted for 28% of the global demand for polyethylene terephthalate (Pet) bottles in 2015. Consumers bought 73.8bn bottles of water in 2016, up more than five billion on the previous year.

The cause is the expanding middle class and rising wages across the board. A generation ago, bottled drinks were still something of a novelty and most Chinese people could remember the first time they tasted Coca-Cola. Now children are brought up on an array of sugary drinks. The plastic bottle has become ubiquitous.

There is also a perception that bottled drinks are more hygienic, and in the wake of a string of food safety scandals – tainted milk powder, fake eggs and contaminated fruit – Chinese consumers believe plastic bottles are less susceptible to tampering.

Plastic presents both environmental challenge and economic opportunity. Despite the increase in plastic, no major city boasts an effective recycling programme. Instead China relies on an army of informal trash collectors. People like Wang Qing.

Wang never expected to work in the recycling industry. She had been a farmer all her life, she married a farmer and never planned to leave the village where she was born. But then the local government took her land, and she moved to Beijing to petition the authorities about getting it back.

She eventually turned to collecting plastic bottles, scouring trash cans across Beijing to support herself.

Almost a decade later, recycling plastic bottles has become her main source of income, and together with her husband, who works as a janitor and brings home bottles from the building he cleans, the pair make about 3,000 yuan (£340) a month on recycling alone. It is enough to rent a small room, feed themselves and pay for basic necessities.

“It would have been very hard to work and at the same time petition the government to give me back my land or compensate me fairly,” Wang said. “I’m lucky because I’m in good shape and I like the exercise of walking the streets.”

A few times a month Wang treks out to the northern outskirts of Beijing, to a village specialising in recycling everything from televisions to air conditioners, from plastic to scrap metal, all stacked in towering piles.

“In China recycling plastic bottles, and recycling in general, is much more of an economic imperative, rather than an environmental imperative like it is in the west,” said Adam Minter, an expert on the recycling industry and author of Junkyard Planet. “It’s extremely rare to see plastic bottles end up in a landfill in China, especially given the higher price point of Pet bottles.”

Still, some citizens are trying to turn the tide before too many people in China become accustomed to a throwaway culture.

“There’s very little thought of the environmental impact of plastic bottles in China. People think about the drink inside, but not about what will happen to the bottle after, so there needs to be more education,” said Mao Da, co-founder of the China Zero Waste Alliance. “Without a government policy aimed at limiting single use bottles, it’s going to be very difficult to slow China’s plastic bottle use.”

Mao is currently focused on encouraging greater use of reusable daily items, such as shopping bags, chopsticks and bottles, as well as partnering with sports events to decrease use of plastic bottles, and he says he’s already seeing results.

“One bright spot is that Chinese people usually prefer to drink hot water, so a lot of people carry their own bottle with them,” he added.

But the informal nature of China’s recycling industry means when prices are low, largely due to low oil prices, there is less incentive to recycle plastic bottles. Still many believe the system suits China better than the civic-minded model touted in Europe and the US.

“It’s going to be really tough to replace the efficiency of the market with a centrally run system of trucks,” said Richard Brubaker, founder of the Shanghai-based sustainability consultancy Collective Responsibility. “In some ways the informal system is better, because city employees are just going to take whatever is in the recyclables bucket; they won’t comb through everything.”