They are an ecologically sound solution to the Earth’s plastic pollution crisis.
That is, if you can keep the grim army of bacteria lurking in your reusable water bottle.
Stomach-pumping studies have suggested the bottles, adored by athletes and Love Island stars alike, may contain 40,000 times more bacteria than the average toilet seat.
For this reason, some experts have described them as a “portable Petri dish.”
Researchers behind US-based waterfilterguru.com conducted one of the grittiest studies on the bugs that still linger in our water bottles. The study examined how colony-forming units (CFUs) were located in four popular types of water bottles. This is a unit commonly used to estimate the concentration of bacteria in a test sample. On average, they contain 20.8 million CFUs of gram-negative bacteria
Researchers also found two types of bacteria in reusable water bottles: gram-negative rods and bacillus. Gram-negative bacteria, including E. Coli and Klebsiella, can cause a number of serious infections, such as pneumonia. Although certain types of bacillus can also lead to gastrointestinal problems including nausea, vomiting and diarrhea
To prevent a buildup of bacteria, experts recommend washing your bottle daily with “warm, soapy water.”
US-based waterfilterguru.com, a team of water treatment experts and members of the Water Quality Association, has conducted one of the starkest studies yet into the bugs that linger in our water bottles.
They found two types of bacteria present: gram-negative rods and bacillus.
Gram-negative bacteria, including E. Coli and Klebsiella, can cause a number of serious infections, such as pneumonia.
While certain types of bacillus can also lead to gastrointestinal problems, including nausea, vomiting and diarrhea.
The study examined how colony-forming units (CFUs) were located in four popular types of water bottles.
This is a unit commonly used to estimate the concentration of bacteria in a test sample.
On average, they contain 20.8 million CFUs of gram-negative bacteria.
Spout and screw cap bottle seemed to hold the most, at 30 million CFUs.
For comparison, a toilet seat has 515.
With an average number of CFUs of 20.8 million, reusable bottles can contain up to five times the bacteria found on a computer mouse (5 million), researchers found.
It also accounts for a whopping 14 times the recorded amount than a pet food bowl, with an average of 1.48 million CFUs.
Other studies have suggested similar values.
Researchers at the US-based air quality laboratory, EmLab P&K, recently found more than 300,000 CFUs per square centimeter on each of the 12 water bottles they tested.
But despite the warnings, experts told MailOnline there was little evidence that the types of bacteria found in these water bottles are harmful to humans.
Dr. Andrew Edwards, a molecular microbiologist at Imperial College London, said: ‘The human mouth is home to a large number of different bacteria.
“So it’s not surprising drinking cups are covered in microbes.”
However, he also warned that household objects, including water faucets, are already riddled with harmless bacteria.
Dr. Edwards added: ‘While it is important to keep bottles clean with hot soapy water, the presence of bacteria is not necessarily a problem.
‘And there is no evidence from this research that the bacterial species found are harmful to humans.
‘Home water taps are indeed often colonized with many bacteria that have no harmful effects on humans.’
Meanwhile, Dr Simon Clarke, a microbiologist from the University of Reading, told MailOnline: ‘It really depends on what the bacteria are as to whether it’s a problem or not.
“Having high numbers of bacteria can be a flag that something hasn’t been cleaned in a while, but it’s not necessarily dangerous.
“I’ve never heard of anyone getting sick from a water bottle, so obviously taps aren’t a problem, when was the last time you heard someone get sick from pouring a glass of water from a tap?”
He added: “Water bottles are probably contaminated with the bacteria already in people’s mouths.”