New Research Study Finds Stored Drinking Water Can Spread Harmful Bacteria

Featured Faculty: Amy Pickering

Every year, over 500,000 children under five lose their lives to gastrointestinal bacterial infections globally, predominantly in areas with inadequate access to safe drinking water, sanitation, and hygiene facilities. But to alleviate this public health threat, scientists need to better understand how these pathogens spread.

A research team from UC Berkeley, led by study principal investigator and CEE Professor Amy Pickering, has revealed that the household setting may significantly influence transmission more than previously recognized. By implementing a novel approach to investigate bacterial strain-sharing patterns, they found that stored drinking water is a crucial pathway for E. coli bacteria transmission within and among households in developing nations. 
 
Their research, published in Nature Microbiology, provides new insights into how contaminated drinking water contributes to the spread of gastrointestinal infections and antibiotic-resistant bacteria, potentially paving the way for effective strategies to safeguard children’s health. According to Professor Pickering, former studies primarily concentrated on the bacterial exchange between humans and animals, while her team chose to explore the role of drinking water and soil as understudied pathways.
 
“We were interested in understanding the role of the household environment in bacterial transmission to humans,” she said. “Our findings showed that water is actually one of the most important transmission pathways for pathogenic and drug-resistant bacteria.”

To see how each of the three main pathways—human, animal, and environment—contributes to bacterial spread in these communities, Pickering’s team developed a scalable, high-throughput bacterial strain-tracking method called PIC-seq (Pooled Isolated Colonies-seq). Using this tool, researchers could sequence up to five bacterial strains per sample instead of one conventional strain per sample.

“PIC-seq proved to be a game changer,” said Pickering. “It enabled us to get more comprehensive views of within and between household strain sharing.”

The team then studied E. coli strain-sharing patterns within two households in informal urban settlements in Nairobi, Kenya. These communal areas typically feature compounds with a shared courtyard. As low-resource communities, they also have limited access to basic services and infrastructure, with household drinking water commonly stored in jerry cans and plastic buckets. 

The researchers collected human stool, poultry, dog feces, and stored water and soil samples from both households. They cultured E. coli colonies from these samples and used PIC-seq to analyze the distinct strains. 

“We found a higher level of strain-sharing between humans and stored drinking water than between humans and domesticated animals within households,” said lead author and CEE postdoctoral researcher, Daniel Daehyun Kim. “These findings underscore that the environment can play just as significant a role in bacterial transmission as animals — or even more so.”

Check out the full research study on the UC Berkeley Engineering website.  

Published