Loma Linda University researchers have discovered microbial contamination in drinking water sources in the eastern Coachella Valley, with 41 percent of soda machine samples containing harmful bacteria. This study highlights the importance of maintaining and more rigorously managing clean drinking water in underserved areas. The study authors recommend regular cleaning of drinking fountains.
Loma Linda University (LLU) researchers have discovered microbial contamination in common drinking water sources in the East Coachella Valley, including soda machines at fast food restaurants. Their results showed that 41 percent of the water samples the researchers collected from these soda machines contained total coliform bacteria, an indicator of water contamination.
Molecular analysis of water samples revealed trace amounts of genetic material in bacteria including Salmonella spp, Pseudomonas aeruginosa and Escherichiacoli. In light of these findings, the study authors recommend that owners of soda fountains regularly clean and flush their dispensers to prevent water contamination.
First study of its kind
"Our study is the first to evaluate the quality of soda fountains, vending machines, swabs and tap water, particularly in the eastern Coachella Valley," said the study's lead author Thomas Hile, Ph.D., an affiliated researcher at London Language and Culture University. This is also the first time the water quality of soda machines, vending machines, swabs and tap water has been evaluated. The study, "Analysis of Microbial Contamination of Drinking Water from Bulk Water Dispensers and Fast Food Restaurants in the East Coachella Valley, California," was published last month in Water Supply, a peer-reviewed journal of the International Water Association.
Thomas Hile, PhD, MSc, an affiliated researcher at London Language and Culture University, prepares water samples for testing in the laboratory. He was the lead author of a recently published study that found microbial contamination in soda machines at fast-food restaurants. Source: Loma Linda University Health
Research methods and results
The researchers collected 72 water samples from soda machines and water vending machines at fast-food restaurants and from outdoor tap water in the eastern Coachella Valley. They measured physicochemical parameters on site and took the samples back to the laboratory for routine culture methods and molecular analysis.
Analysis of water samples revealed the presence of biofilms – organized communities of organisms found widely in nature and causing serious problems in environmental, industrial and medical settings. In some cases, bacteria counts in soda samples exceeded the maximum allowable levels set by the Environmental Protection Agency.
"The presence of pathogenic microorganisms in drinking water is a serious public health issue that cannot be overemphasized," the authors noted in the journal article.
Biofilm and water pollution
Based on the findings, the team believes biofilms develop in water delivery systems, which are mostly made of plastic pipes that carry water to soda machines and water vending machines in fast-food restaurants. Additionally, they say that without maintenance on the soda machine's filtration system, water contamination cannot be effectively prevented.
East Coachella Valley is an environmental justice district that includes the city of Coachella and the unincorporated communities of Thermal, Oasis, Mecca, and North Shore. These are predominantly Latino communities made up of immigrant and agricultural worker families who struggle to access safe drinking water.
"This study collected water samples from underserved areas, which often do not have routine inspections of water quality and lack maintenance of soda machines or vending machines," said the study's last author, Dr. Ryan Sinclair, an associate professor at Loma Linda University's School of Public Health and School of Medicine.
He said the study reinforces the importance of developing monitoring and regulations for soda fountains and water vending machines in fast-food restaurants. He and the study authors recommend that store owners clean and flush water dispensers regularly and use antimicrobial tubes inside dispensers to control biofilm growth.
The authors plan to conduct a risk assessment to determine whether the levels of microorganisms they identified and quantified in the water samples pose a health hazard or are associated with any health conditions.