Researchers from Loma Linda University in California conducted an analytical review of data from 70 studies carried out over the past two decades in five countries, including the United States and the United Kingdom, and concluded that water dispensers often contain levels of bacteria that exceed those found in the tap water sources they supply.
The researchers analyzed bacterial contamination in different types of water dispensers, both those connected directly to the tap water network and those that operate using large water bottles.
The results showed that the surfaces of these devices may become contaminated with biofilms, a protective sticky layer produced by microorganisms, allowing bacteria to survive and multiply inside water tanks, pipes, and filling nozzles.
The study showed that bacterial contamination is not limited to water coolers, but also extends to soft drink vending machines, where bacterial growth was recorded just a few days after some devices were sterilized.
The bacteria detected included fecal coliforms, bacteria associated with human and animal waste, which can increase the risk of gastrointestinal illnesses such as nausea and vomiting, and in rare cases, infection with them can be fatal.
Dr. Ryan Sinclair, an environmental microbiologist and participant in the study, explained that the water filtration process in these devices removes residual chlorine, creating a suitable environment for bacterial growth, stressing the need to clean the pipes and change the filters regularly.
Unlike tap water, which usually contains small amounts of chlorine that kill microbes, water coolers and dispensers may allow water to pass through without disinfectants, allowing bacteria to multiply, especially on the moist surfaces of nozzles and distribution outlets.
Experts warned that neglecting to clean devices or replace filters regularly could turn these filters into a breeding ground for bacteria, instead of their intended protective role.
The researchers indicated that the aim of the study was to raise awareness of the potential health risks associated with water dispensers and coolers, and to advocate for adherence to regular maintenance and cleaning procedures.
Led by Dr. Thomas Hale, a water quality expert at Crafton Hills College in California, the research team recommended cleaning water dispensers every two to four weeks, or weekly in case of heavy use.
The study was published in the journal AIMS Microbiology.
