“A friend and I bought a bottle of Cutty Sark whisky here once,” says Beijing-based marketing consultant Blake Stone-Banks, sitting on the terrace of a rough and rammed bar in Sanlitun, one of the Chinese capital’s busiest commercial areas.

“It tasted funny so we limited ourselves to one glass each,” he says. “Later, I received a call from my friend’s wife telling me that he’d fainted. I went to see them in hospital and he was unable to speak. He was given a drip and waited it out for a few hours.”

Stone-Banks is sure that the cause of the collapse was fake alcohol, the black market supplying it having exploded in China in the past decade alongside the expansion of the bar industry there. Fake alcohol is generally either illegally made, unregulated drink – think bathtubs and grubby tubes – or, more commonly, cheap but legally produced alcohol placed in higher-end bottles and passed off as the brand on the label.

No one knows how much of the legitimate alcohol industry in China is eaten into by such fakery, but industry figures suggest it’s significant. Brown-Forman, the company that makes Jack Daniel’s, estimates that around 30% of all alcohol in China is fake.

Health risks

In its Global Status Report 2014, the World Health Organisation reported that per capita alcohol consumption in China increased from 6.7 litres in 2010 to 8.8 litres in 2012, a 31% rise in two years. If Brown-Forman’s figures are correct, even a conservative estimate suggests that on average every Chinese adult is knocking back a couple of litres of fake alcohol a year.

“Drinking fake alcohol is dangerous – you just don’t know what you’re consuming,” says Dr Bernhard Schwartländer, the WHO’s representative in China. “Where counterfeit alcohol is made from poor quality ingredients or toxic industrial chemicals, consuming it could lead to serious acute illness or worse in the short term, and potentially a host of medium- and longer-term health problems.”

The chemicals Schwartländer refers to include ethylene glycol, which is antifreeze, methanol, which can cause blindness, and isopropyl alcohol: all commonly found in Chinese fake alcohol, all dangerous. The nasty bathtub booze is most likely to contain these, but the more common scam of filling high-end bottles with cheap alcohol can cause more harm than a headache and the feeling of being short-changed.

In south-east China’s Guangdong province last year, for example, police busted a gang that had been refilling top-brand whisky bottles with 30 yuan-a-bottle (£3), locally made liquor. Conditions were perilously unsanitary, with police reporting bottling taking place in toilets.

That bust followed a crackdown in 2012 and 2013, with police reporting many successful raids and tens of thousands of confiscated bottles. Such reports have since become rare but, despite the issue becoming a lower priority for Chinese authorities after their previous flurry of arrests, many in the alcohol industry believe that the problem is as bad in 2015 as it has ever been.

A tough one to tackle

One of them is Bill Isler, an American who has been running Beijing bars with a “no fake booze” policy since 2005. He says that even reputable distributors have fake alcohol on their price lists. “I know bars that serve £1-a-bottle vodka in Smirnoff bottles,” he says. “It’s worse outside Beijing. In karaoke bars I’ve been to, the whisky is undrinkable. It’s not even whisky, it’s some kind of vodka mixed with flavouring and colouring.”

Most spirits in China are drunk with mixers and, although interest in them among the middle classes is rising, most imported brands are relatively new on the scene and it’s easy for shoddy knockoffs to be passed off as the real thing. The rule can apply to champagne too, with one Shanghai nightclub manager telling me last year: “These may be people who have suddenly come into money, they’re drinking Dom Perignon – they have no idea what it is.”

To stay ahead of the game, many fake alcohol producers are becoming savvy to the emergence of high-end bars in cities such as cocktail mecca Shanghai. “Even some of the most reputable bartenders in China can’t recognise the more realistic knock-offs,” says Daniel Taytslin, managing director of Gotham East, a company that imports specialist alcohol to the country.

Tax rates on alcohol imports to China are high. Booze bottles brought into the country are supposed to carry import stamps that serve to protect legitimate importers’ goods from being replaced by counterfeiters, as well as to prove their legality, but many criminals are one step ahead. Taytslin said that counterfeiters were getting very good at removing unique identifiers that brands place on their bottles.

Spirit companies such as Bacardi work with Chinese bars to promote refined drinking that is at odds with fake alcohol consumption, bringing in guest bartenders and holding cocktail competitions. But ground-level battling is usually left to those running the bars. David Schroeder, a former US policeman who runs Shanghai’s popular Senator Saloon bar, has taken to smashing his empty liqueur bottles after he discovered suspected fake booze dealers attempting to buy them from his staff.

Despite these barriers, Taytslin is hopeful that Chinese society will become less tolerant of fake alcohol as it gets accustomed to more imports. “It’s going to get better eventually because the younger generation here is becoming more interested in their drinks,” he says, “just like this generation is complaining more about pollution.”

This awareness may take more time to hit the cheaper establishments of Beijing. Back inside the Sanlitun bar, Stone-Banks eyes up a bottle of whisky labeled as Jim Beam. In a nearby cocktail bar it costs 60 Yuan a shot, here it’s 95 Yuan a bottle. He orders a beer instead.

• This article was amended on 17 September 2015. The original misquoted Daniel Taytslin as saying that counterfeiters were producing fake import stamps.