Researchers in Guatemala's Western Highlands discovered a stark mismatch between public perceptions of drinking water safety and actual contamination levels. Bottled water, widely trusted as the safest option, proved most prone to harmful bacteria, while protected municipal wells emerged as the cleanest sources. The findings, published in the Journal of Water and Health, underscore risks to public health from unsafe water.
A team from Washington State University conducted a study in Guatemala's Western Highlands, surveying 60 households across urban and rural areas to assess drinking water quality against local beliefs. Residents often ranked large refillable jugs of bottled water as the safest choice, yet lab tests revealed it was six times more likely to contain coliform bacteria—indicators of fecal contamination—than other sources. Only 17% of bottled water samples met World Health Organization standards for safe drinking water.
Across the 11 water sources examined, coliform bacteria appeared in 90% of samples, Escherichia coli in 55%, and extended-spectrum beta-lactamase-producing (ESBL) bacteria in 30%. Carbapenem-resistant Enterobacterales (CRE) were rarer but present in some household piped water. These antibiotic-resistant organisms pose serious threats, as they can cause hard-to-treat infections if they enter the bloodstream or urinary tract.
Protected municipal wells, despite lower trust among residents, showed no coliform, E. coli, ESBL, or CRE contamination due to sealing and chlorination. However, contamination rose once water reached homes via pipes, with over 65% of samples containing coliform and 28% E. coli.
"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 lead author Dr. Brooke Ramay, an assistant research professor at WSU's Paul G. Allen School for Global Health. She noted that trusted sources like bottled water lead to skipped precautions, such as boiling or cleaning dispensers. "The problem isn't usually with how the water is bottled—it's what happens afterward," Ramay added, pointing to improper storage and unclean dispensers as key issues.
Globally, unsafe water affects over 4 billion people, fueling millions of diarrheal cases yearly, particularly in children, and spreading antimicrobial resistance. The study highlights how cultural perceptions can exacerbate risks by discouraging hygienic practices.
