The era of drinking water from the tap has been over for years, says Li Fuxing, director of the Beijing Institute of Public Health and Drinking Water. But there are no guarantees that the water you take from a dispenser is safe, either.
There are too many opportunities for contamination, in every step of the process, from water source to the 18.9-liter container that is delivered to your home or office.
Choosing a relatively reliable brand can lower the risk. But before that a thorough understanding of drinking water and the dispensing industry is more effective than buying by price or brand name.
"In China, people's level of knowledge about drinking water is unbelievably low," said Li, who has been conducting research in water and health for almost 20 years.
They don't know, for example, that they should drink eight to 10 glasses of water a day.
He reached that conclusion based on an online survey, released in March, that drew about 70,000 responses - 80 percent of which showed ignorance of the basics of water and health. Still, Li said, the proliferation of choices in drinking water shows that consumers want to do the healthy thing.
First, they know that many sources of drinking water are fouled by industrial waste or other sources of pollution. On Sunday, for example, water experts arrived in Qujing, Yunnan province, to investigate after highly toxic waste was dumped at a water source - not a rare occurrence.
Second, Li has said previously that the delivery of treated water often means traveling through pipes that could be 60 years old and risks from byproducts of disinfectant chlorine.
So 10 million people subscribe to water dispenser services, spending more than 30 billion yuan ($4.7 billion) annually, Li said. Asia tops the world in the growing pace of the industry, and China leads the way with a rate of roughly 20 percent a year.
In some cities, Li said, more than 60 percent of households get their drinking water delivered in the big bottles, sometimes called barrels. Yet on July 6, the capital's industry and commerce administration reported that 31 water brands had failed regular safety checks. All exceeded the allowable count of aerobic bacteria; one brand, Liquan, was 9,000 times over the limit.
In an interview with China Daily, Li broke down the hidden dangers in the production and distribution processes for water that comes in "barrels".
He started, logically, at the water source. Most of the water, especially mineral water, comes from the aquifer deep underground. When pollution occurs in nearby, contaminants can easily sink into the groundwater.
"I saw it with my own eyes in Jiangxi province, where local people raise ducks and do their washing up near a water source," Li said.
In addition to sources of ordinary water, about 3,000 sources for mineral water in China are considered qualified, meaning they meet certain standards for the level of minerals in the water, or did at the time they were certified.
After that, he said, few follow-up checks are conducted. "Authorities pay most attention to the finished products."
The water is then pumped into the production line, which is supposed to precipitate the sediment and purify the water. However, Li said, "Pipelines and the filtration system need backwashing and cleaning on a regular basis. Otherwise the disinfection process itself will become a contamination process."
Beyond regular spot-checks by authorities, the drinking water industry relies heavily on checks by the factories themselves. This usually occurs after the water has been bottled and before it is shipped, Li said.
"No companies, big or small, can guarantee that all of their products meet quality standards. That's why the self-check mechanism is a must," he said. "If it exists only in name, as in many cases I know about, there will be higher possibilities for substandard products to reach customers."
Then there is the quality of the containers. Standards for individual-size water bottles are lower because those bottles are not reused. But the big jugs, usually holding 18.9 liters, are usually reused about 40 times each.
These bottles are supposed to be made of food-grade polycarbonate. Statistics released by the China National Health Association drinking healthy committee indicate the annual nationwide output is about 15 million; demand exceeds 20 million.
Li said it is no secret in the industry that about half of these large bottles do not meet appropriate standards.
While doing research in Hebei province, Li said, he saw workers from small illegal workhouses smash waste DVDs and small plastic bottles into granules and sell them to factories that make the big water bottles.
"Water is contaminated if it is kept in vessels like this. People may feel a stomachache or get dizzy if they drink this water for a long time," Li said.
"Price competition is hot in the industry, and the bottles account for the biggest portion of the total cost." Li said bottles that meet standards cost at least 30 yuan.
Forged bottles are hard to identify, Li said, even by professionals.
If you lift a standard bottle and a substandard one together against the sun, he said, it's clear that the "good" bottle is a transparent light blue, with no impurities. The substandard bottle is darker and rougher, with low transparency and more scratches.
When such a comparison isn't possible, Li said, it's hard to make a distinction.
The biggest risks occur after the filled bottles leave the production plant.
Few companies in the industry have retail operations. Instead they rely on dealers and distributors to sell and deliver their water, and that's when they lose control of their products.
"Some distributors simply pump tap water into the bottles that are labeled as famous brands. Some replace qualified bottles with substandard ones," Li said. "The authorities care most about the producers. There is hardly any supervision in this segment."
Even when the water reaches the customer, risks remain.
The large jugs require the use of a water dispenser. Li said many people think the dispensers are convenient and safe but don't think to clean them often enough. They also should consume the water within a week, he said.
"What they usually don't know," he said, "is that once the barrel is loaded onto the dispenser, air and dust start to come inside, making it a comfortable reproduction site for germs."
Air has to be introduced into the barrel to allow water to drop into the dispenser. That's the process that produces the large, sometimes loud bubbling.
Li and his colleagues once performed an experiment that produced countless bacterial colonies in the water within four days.
"Once the seal is opened, the water must be stored in a place with no direct sunshine and be finished within a week," Li said. "And the dispenser should be cleaned at least every month."
Despite all the potential risks, Li said, water from the 18.9-liter bottles is a safer choice than tap water and water from the automated sellers installed outside many communities. But he urged consumers to learn more about drinking water.
"The quality of life is determined by the quality of water," Li said.