Fans of Beijing's many hot springs resorts are being warned that some of them are not the real thing.

An official in charge of terrestrial heat management says at least four fake hot springs resorts have been identified so far out of the 70 in the Beijing area.

Chen Jianping, director of the terrestrial heat management department within the Beijing Municipal Bureau of Land and Resources, said testing is continuing of the area's hot springs resorts and the results will be published as soon as possible.

Chen said his department is working with the China Mining Association and China Consumers' Association on carrying out the tests.

And he said efforts will be stepped up to regulate Beijing's hot springs market.

Fake hot springs resorts use several tricks to fool customers.

"So far, we have found three primary means of forging hot springs," Chen said.

"The first one is to blend hot springs water with hot tap water. The second is to name a spa club a hot springs center, even though it doesn't provide any hot springs services. The last one is to add traditional Chinese medicine to heated tap water and claim it is a natural hot spring," he said.

The testing is in the early stages but so far it has identified some genuine resorts. He said HongFu Hot Spring Leisure City and seven other hot spring centers have been verified so far.

Chen refused to name the fake hot springs resorts.

He said they would be detailed once the testing is complete.

Hot springs resorts are one of the favorite recreational destinations of Beijingers in the cool weather. The number of visitors to hot springs has doubled compared to the same period last year.

A two-day visit to suburban hot spring centers was listed on by ctrip.com as one of the most popular attractions at this time of year.

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The cost of visiting hot springs in Xiaotangshan, which is famous for its abundant and high-quality springs, ranges from 170 yuan to 280 yuan per person, qianlong.com reported.

The statistics also show that hot springs tours in December are already open for reservations and more than 60 percent of the tours have been booked.

Zhang Ran, a sales representative with a private-sector IT firm, is a big fan of hot springs and has a membership card at Chunhuiyuan Warm Spring Resorts. She said she has also been to a hot springs center in Shunyi district twice this year.

"My work is very stressful. Hot springs can help me ease the pressure and it is very good for my skin," she said.

Zhou Xun, a professor of water resource studies at China University of Geosciences, said hot springs offer a pleasant way to keep healthy.

Zhou said they are beneficial for calming the mind and speeding up blood circulation.

People suffering from neurasthenia or insomnia also find relief after taking a low-temperature hot spring bath.

He told METRO there are four ways to spot a fake hot springs resort:

Firstly, a real one will have a mild smell of hydrogen sulphide, which is similar to the smell of stinky eggs.

Secondly, one's skin feels smooth and slippery after soaking in real hot spring water.

Third, bathers feels a mild buoyant force when lying in hot spring.

And lastly, a bather's skin will not wrinkle, no matter how long they stay in the water.