Certain tragic cases notwithstanding, bacteria in treated water is usually of a harmless kind. But research to date has not characterized exactly how a given collection of bacteria ends up in the treated water.
A paper published by scientists at the University of Michigan, and reported in Science Daily, looked at a water treatment plant in Ann Arbor, Michigan, and asked: What is it that affects the microbiome of drinking water? And is it possible to manipulate that microbiome with current water treatment technologies?
|Water glass (Source: Wikimedia Commons, Svebert )|
It was news to me that water basically goes through 2 processes before it makes its journey to your tap: (1) filtration, and (2) disinfection. As you can imagine, the bacteria present in the water change after each of these steps. These authors were determined to get a picture of exactly how the microbiome changed with each step in the treatment process.
They found that although water from the source "seeded" the drinking water with bacteria, the tap-ready water had quite a different microbiome.
The process that seemed to affect the drinking water most of all was filtration. The water filters in the treatment plant had stable bacterial populations that seemed to change all the water passing through them. Even the water treatment process #2, disinfection (commonly involving chlorine), didn't affect the bacterial populations as much as the filters did. Changing certain aspects of the filtration process could therefore, in theory, affect the bacteria in the water that reaches the population.
So here we have an opportunity, say the researchers. If the filter is the key to manipulating the drinking water microbiome, couldn't we custom-design that microbiome?
As it is, we trust technicians to make sure all water leaving the local water treatment plant contains innocuous bacteria. But why not go further? Why not make sure all the water has bacteria that actively out-compete risky bacteria? Or better yet, why not make it probiotic water, which contains only those bacteria with a measurable benefit to human health?
Working toward probiotic drinking water seems to me like a worthy public health endeavor. Taking the bacteria that are inevitably present in drinking water and ensuring that, as much as possible, they are bacteria that endow a health benefit could boost the health of hundreds of millions of people. (It also beats probiotic drinking straws, which purportedly make any drink into a probiotic drink. Is it just me, or is there something creepy about probiotic Red Bull?)
We know that a lot of the things we do in daily life have a harmful effect on our gut bacteria. (For some of the details, see posts labelled Flora Killers.) So attempting to make up for that by drinking probiotic water straight out of the tap is a promising idea. Some would call this an ecological approach to gut health: essentially, taking an understanding of how bacterial species interact with each other, and using that to create a community of microbes that can live happily when left to their own devices. Adding everyday probiotics to create a healthy ecosystem in your intestines, if you will. In the future - and with a lot more dedicated water research on the drinking water microbiome - it just might be possible.
Pinto, & Raskin (2012). Bacterial community structure in the drinking water microbiome is governed by filtration processes Environmental Science & Technology DOI: 10.1021/es302042t