Imagine a remote, sparkling mountain spring—one so clear you can see through it. Drinking water from a pure, natural source sounds good, doesn't it?

Proponents of the "raw water" trend of drinking naturally sourced, untreated, unfiltered water, water sourced seemingly far from contamination, suggest that this movement can help us avoid the fluoride and trace chemicals that can be found in tap water and instead drink naturally found minerals.

But let's take a closer look, starting with some of the chemicals that can be found in tap water that concern raw water proponents. How else could we address these concerns? And is raw water really better?

When you turn on your faucet for a drink of water, it's just one part of the larger water cycle across Earth's land, ocean, and atmosphere. Within this larger cycle, water is used by humans and then put back into circulation. Unfortunately, this also means that chemicals from weathering, pollution, or wastewater can be introduced, including many classes of drugs, such as antibiotics used by humans or animals that are then excreted, as well as chemicals from personal care products. These chemicals tend to measure in the range of parts per billion and trillion, meaning they are detectable but appear in very small amounts. The effects on humans of such low levels of chemical exposure aren't currently clear. However, these low levels of chemicals can be found in natural environments, too—and water that appears clean can be deceptive, meaning that monitoring and treatment of drinking water is necessary.

Raw water advocates mention heavy metals as another concern and source of contamination in drinking water; lead is a prime example, as seen with the recent cautionary tale of the appearance of elevated lead levels in the drinking water of Flint, Michigan, when the city began sourcing its water from the polluted Flint River. The federal action level for lead in drinking water is 15 ppb, and Flint's action level was nearly double that, at 27 ppb. Cases like Flint's are very rare, and the geometric mean of lead in U.S. drinking water is 2.8 ppb, typically due to corrosion of older plumbing material that contains lead. But careful treatment and monitoring for lead continues to be needed for all drinking water to prevent such cases in the future.

Fluoride, a chemical added during water treatment, is another concern of raw water enthusiasts because, like any compound present at too-high doses, it can cause mottled teeth and skeletal problems. But at the low doses used in public drinking water, fluoride is actually beneficial, providing far-reaching prevention of dental caries to all people in a community. Fluoridation of drinking water has greatly reduced the occurrence of dental caries, strengthening tooth enamel by converting hydroxyapatite, a mineral that is the main inorganic constituent of tooth enamel, to fluorapatite, which promotes remineralizing of the enamel. While fluoride is also present in toothpaste, prevention of caries requires frequent use, and fluoridation of water, which we all need to drink—frequently—makes that easy. Fluoride may also act as an antimicrobial agent toward microbes within polymicrobial oral biofilms, which can create an acidic environment by utilizing carbohydrates eaten by humans, leading to dental caries.

Furthermore, skipping the treatment steps in drinking water comes with major biological risks. We live in a microbial world, and many pathogens could be present in unfiltered and untreated water, such as enteric bacteria (including Shigella, E. coli, Campylobacter, and Salmonella), viruses (norovirus and hepatitis A virus), and parasites (e.g., Giardia and Cryptosporidium). I'm not alone in raising these concerns about all the cool (microbial) friends you could meet drinking raw water. Historically, when chlorination and water treatment began to be used in the U.S., along with greater sanitation measures, waterborne diseases and deaths were greatly reduced from infectious disease even before the introduction of antibiotics, making water treatment a major public health achievement.

I can't stress enough how many lives have been saved because of functioning water and wastewater treatment facilities. Access to clean drinking water should be a human right. The United Nations agrees: clean water access is one of the UN Sustainable Development goals, with functioning water treatment facilities identified as a way to save children dying of diarrheal diseases caused by waterborne pathogens.

Even though tap water is already better for you than raw water, here are some ways that researchers are making it even safer:

Better monitoring and detection techniques

Once pharmaceuticals and chemicals from personal care products enter the water cycle or are used in agricultural applications, they can be taken up by the roots or aerial tissues of plants. Mireia Bartrons and Josep Peñuelas propose in Trends in Plant Science that plants could be used to monitor the presence of these pharmaceuticals or chemicals in the environment and, further, to even remove these chemicals, via phytoremediation. The authors call for further study about the mechanisms by which plants take up these chemicals, and about the chemicals' bioaccumulation and potential toxicity.

In Trends in Biotechnology, Sergio Jarque and colleagues review how yeast biosensors can be used for detection of environmental pollutants. These are ideally high-throughput systems of engineered yeast with a receptor for the chemical of interest. Sensing of the chemical causes a specific response within yeast that is detected by either electric current or reporter gene activity, and yeast biosensors have been used in labs to sense estrogens, progestogens, androgens, and heavy metals from water samples. As detection technologies improve, we will have a better sense of the spread of pharmaceuticals and personal care product chemicals in our environment, which would be a good starting point for monitoring with an aim to reduce these chemicals in the water supply.

New ideas for water treatment, collection, and distribution

One way to mitigate the risk of lead leaching into drinking water would be to replace our drinking water piping system, but this would be a costly undertaking. Alternatively, absorbent materials could be used in water treatment and delivery to remove lead, such as open-framework aluminosilicate zeolites, also called molecular sieves, as reviewed by Jihong Yu and colleagues in Chem.

But if we could get water from the atmosphere at the point of use, this would eliminate the need for a distribution system, which would be particularly beneficial in places where water distribution systems do not currently exist. A recent preview in Chem by Adam Rieth and Mircea Dincă highlights work done with atmospheric water generators that utilize a metal-organic framework sorbent material, MOF-801, to directly harvest water vapor from the atmosphere.

So please, go ahead and drink the water from the tap! Even with its flaws, it's better than raw water. But even more, let's work to expand access to clean water, minimize pollutants, and improve the wastewater treatment process to allow access to a better quality of water for all.