Water that comes straight from natural sources, dubbed “raw water,” is gaining popularity. Raw water advocates reject public water supplies, including tap water, because they don’t enjoy the taste or believe it’s unsafe and depleted of vital minerals.
On the surface, raw water might seem alluring – the natural surroundings may look beautiful, and the water may look clean and taste refreshing. But unlike tap or commercially bottled water, raw water is not evaluated for safety. This leaves the people who drink it vulnerable to infectious microbes or potentially other toxic contaminants.
I’m a microbiology researcher studying infectious diseases. From a public health perspective, clarifying misconceptions about tap water and the health hazards of raw water can protect consumers and curtail the spread of infectious diseases.
A short history of public drinking water
Archaeological evidence suggests that humans have long associated dirty water with negative health outcomes. As early as 1500 BCE, ancient Egyptians added a binding agent to their water to clump contaminants together for easy removal.
Two major developments in the mid-1800s showed why impure water is dangerous. First, physician John Snow traced a deadly cholera outbreak to contaminated water from London’s Broad Street pump. Second, Louis Pasteur advanced the germ theory of disease, which postulated that microbes can cause illness. Pasteur established that consumable liquids like raw water and milk can harbor disease-causing pathogens.
Physician John Snow’s 1854 map of cholera cases in London, highlighted in black, clustered around a contaminated pump.
John Snow/Wellcome Collection
These discoveries paved the way for large-scale infrastructure projects in the 20th century to ensure the public water supply is safe.
Today, the process of cleaning water begins with the same steps employed by the ancient Egyptians, followed by extensive filtration to get rid of debris as well as most germs and chemicals. Chlorine is added to kill lingering pathogens, including those that may reside in the service pipes carrying the water to the faucet. Beginning in the 1940s, a small amount of fluoride was added as an inexpensive, safe and effective means to improve dental health.
The cleanliness and fluoridation of the water supply has dramatically reduced infectious disease and cavities, and has been heralded as one of the 20th century’s greatest public health achievements.
Is raw water healthier than tap water?
People who champion raw water claim it has health benefits, such as essential minerals and beneficial bacteria called probiotics, that are stripped from tap water. Let’s unpack each of these claims.
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