PULLMAN, Wash. - A Washington State University-led study in Guatemala found the sources of drinking water people believe to be safe and clean often contain potentially dangerous bacteria.
Focusing on the Western Highlands region of Guatemala, researchers examined how community perceptions of water safety compared with actual water quality. While residents overwhelmingly believed bottled water sold in large refillable jugs to be the safest option for drinking, researchers found that of 11 water sources tested it was the most frequently contaminated with coliform bacteria - an indicator of fecal contamination. The findings were published in the Journal of Water and Health.
"We found there is a clear disconnect between what people believe about water safety and what's actually happening in their homes, and that can have major public health implications," said Dr. Brooke Ramay, lead author and assistant research professor in the WSU College of Veterinary Medicine's Paul G. Allen School for Global Health.
Unsafe drinking water is a major global health threat, with more than 4 billion people worldwide lacking access to safely managed water and fecal contamination contributing to millions of cases of diarrheal disease annually, especially among children. Contaminated water is also a growing concern in the spread of antimicrobial-resistant bacteria.
"Understanding how people view water safety is key to improving public health," Ramay said. "When people believe their water is safe, they don't take extra precautions, but when they see a risk, they change their behavior."
Ramay's team surveyed 60 households - 30 urban and 30 rural - and collected samples from drinking water sources, including bottled, piped, well, spring and filtered water. Samples were tested for coliforms, Escherichia coli and extended-spectrum beta-lactamase-producing (ESBL) and carbapenem-resistant Enterobacterales (CRE), bacteria that can survive many commonly used antibiotics and cause hard-to-treat infections. Both ESBL- and CRE-producing bacteria often live harmlessly in the human gut, but if they enter the urinary tract or bloodstream, they can cause infections that are extremely difficult to treat.
Despite bottled water being perceived as the safest, it was six times more likely to test positive for coliforms than other sources. Only 17% of bottled water samples collected in the study met World Health Organization standards for safe drinking water.
Many households in Guatemala rely on bottled water as their main source of drinking water. The jugs are typically filled at local purification plants or neighborhood refill stations, where water is treated before being sealed and delivered to homes and businesses.
"The problem isn't usually with how the water is bottled - it's what happens afterward," Ramay said. "These jugs can be stored improperly, and dispensers aren't cleaned regularly, and we think this can create ideal conditions for bacteria to grow."
Across all water sources tested, researchers found coliform bacteria in 90% of samples, E. coli in 55% and ESBL in 30%. CRE, a particularly concerning form of antimicrobial-resistant bacteria, were rare but detected in some samples of piped household water. Finding these organisms in drinking water is especially concerning because they can spread antibiotic resistance, even without causing illness.
Despite being ranked lower in perceived safety, water from protected municipal wells - which are sealed, chlorinated and maintained community sources - had the lowest on-site contamination rates, with no samples testing positive for coliforms or no detectable E. coli, ESBL or CRE bacteria.
When municipal water was piped into homes, however, more than 65% of samples were contaminated with coliforms, while 28% had E. coli (28%), 11% ESBL and 11% CRE (11%).
The study also revealed how cultural beliefs influence behavior. People who trust their water source are less likely to boil or treat it, or in the case of bottled water, to clean dispensers.
"Our results suggest that beliefs about water safety may actually contribute to contamination because people don't take the same hygienic steps with sources they trust that they might with other less trusted sources," Ramay said.
