October 9, 2023 – A small study in California found that 4 out of 10 samples taken from soda fountains contained potentially dangerous contaminants. The study also raised concerns in regards to the safety of water sold in stores by refilling large take-away jugs.
The research results of microbiologists at Loma Linda University were recently published within the journal Water supply.
For the study, researchers took 72 samples from three forms of water sources: soda fountains, water vending machines, and tap water faucets within the stores where the water vending machines were positioned. Water vending machines are people who fill large jugs, typically in grocery stores, that customers then take home.
All samples for the study were taken from the desert region of southern California, the so-called Eastern Coachella Valley.
The fast-food restaurants where the samples were collected were unaware of the study, and the researchers purchased food and drinks on the locations where the samples were collected.
They found bacteria called total coliforms in:
- 41% of soda fountain samples
- 20% of samples from water dispensers
- 50% of the tap samples from the shops where the water dispensers were installed
- 88% of swab samples from water dispensers and tap water faucets
According to the US Environmental Protection Agency“The presence of coliform bacteria in tap water indicates that there may be a problem with existing equipment or treatment systems, contamination of the source water, or a break in the distribution system that E. coli Contamination.”
E. coli According to the EPA, water contamination is usually associated with feces. But samples that test positive for total coliforms do not necessarily mean that the water is contaminated with E. coliand the EPA recommends further testing of water that tests positive for total coliform.
The Loma Linda researchers also tested water directly from the local water utility and found that the samples were all within safe limits. They concluded that the sources of contamination in their other tests were pipes and appliances.
“Although the Coachella Water District provided clean water, based on the results published on its website and the analysis of the water tank we analyzed, we can assume that the [tap water] Faucets, fittings or other pipes in the building are likely to be contaminated with biofilms,” the authors write.
Biofilms are a Mucus layer of microorganisms that form on surfaces that come into contact with water.
A water research expert at Michigan State University who was not involved in the study said the results showed that more monitoring was needed.
“It is concerning that they found these pathogens,” said microbiologist Joan Rose, PhD, of Michigan State USA Today“This is clearly a sign that we want to do more research of this sort. We simply don't understand how big the threat is.”
A representative of the National Restaurant Association told the news agency that soda fountains have to be cleaned often under federal guidelines, and noted that there are known problems with tap water quality in the neighborhood where the study was conducted.
“We encourage restaurant operators to work with their suppliers to learn and understand the best ways to clean and disinfect all food-contact surfaces in accordance with the Food Code and applicable local laws, regulations and guidelines,” said Patrick Guzzle, MA, vp of food science on the National Restaurant Association.
The authors stressed that their results give cause for concern.
“The presence of pathogenic microorganisms in drinking water is a serious public health problem and cannot be overemphasized,” they wrote.