By Dr. Tim Sandle
SCIENCE EDITOR
DIGITAL JOURNAL
January 24, 2026
Well water. Image by Tim Sandle
Unsafe drinking water continues to be a serious global health issue. More than four billion people around the world lack access to safely managed water, and faecal contamination contributes to millions of cases of diarrheal illness each year, especially among children.
An example of this has recently been detected in Guatemala’s Western Highlands, where researchers from Washington State University have found that a source of drinking water that people trust most may actually be the riskiest.
Here, bottled water from refillable jugs—seen as the safest choice—was frequently contaminated with harmful bacteria; instead, protected municipal wells were found to be the cleanest
January 24, 2026
Well water. Image by Tim Sandle
Unsafe drinking water continues to be a serious global health issue. More than four billion people around the world lack access to safely managed water, and faecal contamination contributes to millions of cases of diarrheal illness each year, especially among children.
An example of this has recently been detected in Guatemala’s Western Highlands, where researchers from Washington State University have found that a source of drinking water that people trust most may actually be the riskiest.
Here, bottled water from refillable jugs—seen as the safest choice—was frequently contaminated with harmful bacteria; instead, protected municipal wells were found to be the cleanest
.
Looking down a well (in Italy). Image by Tim Sandle.
Bottled water is not necessarily best
The study focused on Guatemala’s Western Highlands, where scientists compared what people think about their drinking water with what laboratory testing actually revealed.
To gather the data, the research team surveyed 60 households, split evenly between urban and rural areas, and collected water samples from several sources, including bottled, piped, well, spring and filtered water. The samples were analysed for coliform bacteria, Escherichia coli, and antibiotic-resistant organisms such as extended-spectrum beta-lactamase-producing (ESBL) and carbapenem-resistant Enterobacterales (CRE).
These bacteria can survive many commonly used antibiotics and cause infections that are difficult to treat. Although ESBL- and CRE-producing bacteria often live harmlessly in the human gut, they can cause severe illness if they enter the urinary tract or bloodstream.
Many residents viewed bottled water sold in large refillable jugs as the safest choice. However, testing showed that among the 11 water sources examined, bottled water was the most likely to contain coliform bacteria, which signal faecal contamination. In addition, some of these microbes are antimicrobial resistant.
Barman pouring bottled water. Image by Tim Sandle.
As lead scientist, Brooke Ramay, says: “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.”
Promoting public health
“Understanding how people view water safety is key to improving public health,” Ramay adds. “When people believe their water is safe, they don’t take extra precautions, but when they see a risk, they change their behaviour.”
Environmental Impact: The production, transportation, and disposal of plastic bottles from bottled water contribute to pollution and resource depletion. In contrast, well water systems eliminate the need for plastic bottles, reducing waste and carbon footprint
Risk of drinking bottled water
Despite being widely trusted, bottled water was found to be six times more likely to test positive for coliform bacteria than other water sources. Indeed, only 17% of bottled water samples met World Health Organisation standards for safe drinking water.
This is a national problem since bottled water serves as the primary drinking water source for many households in Guatemala. Large jugs are commonly filled at local purification facilities or neighbourhood refill stations, where the water is treated, sealed and delivered to homes and businesses.
In contrast, water drawn directly from protected municipal wells had the lowest contamination levels, even though residents ranked these sources lower in perceived safety. These sealed, chlorinated community wells showed no coliform contamination and no detectable E. coli, ESBL or CRE bacteria. This presents a cogent case for ‘free’ water as opposed to expensive bottled water.
As lead scientist, Brooke Ramay, says: “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.”
Promoting public health
“Understanding how people view water safety is key to improving public health,” Ramay adds. “When people believe their water is safe, they don’t take extra precautions, but when they see a risk, they change their behaviour.”
Environmental Impact: The production, transportation, and disposal of plastic bottles from bottled water contribute to pollution and resource depletion. In contrast, well water systems eliminate the need for plastic bottles, reducing waste and carbon footprint
Risk of drinking bottled water
Despite being widely trusted, bottled water was found to be six times more likely to test positive for coliform bacteria than other water sources. Indeed, only 17% of bottled water samples met World Health Organisation standards for safe drinking water.
This is a national problem since bottled water serves as the primary drinking water source for many households in Guatemala. Large jugs are commonly filled at local purification facilities or neighbourhood refill stations, where the water is treated, sealed and delivered to homes and businesses.
In contrast, water drawn directly from protected municipal wells had the lowest contamination levels, even though residents ranked these sources lower in perceived safety. These sealed, chlorinated community wells showed no coliform contamination and no detectable E. coli, ESBL or CRE bacteria. This presents a cogent case for ‘free’ water as opposed to expensive bottled water.
Storage problems
The problem is not usually with how the water is bottled, rather it is what happens to the water afterwards. The 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 samples tested, coliform bacteria were detected in 90% of water sources, E. coli in 55%, and ESBL in 30%. CRE bacteria were less common but were found in some household piped water samples. The presence of these organisms in drinking water is particularly concerning because they can spread antibiotic resistance even when they do not cause immediate illness.
The research appears in the Journal of Water and Health, the research paper is titled “Comparing cultural perceptions of drinking water safety with water quality in urban and rural Guatemalan communities.”
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