You can buy water with electrolytes, minerals or completely "purified." You can buy it with the pH changed to make it alkaline. You can purify your own tap water or even add nutrients back into it. But after seeing a video of a pricey, high-tech filter (about $400 U.S. on sale) that you can monitor with your phone, we wondered, how much of our water filtration fixation is healthy, and how much of it is hype?
As it turns out, scientists say that most tap water in the U.S. is just as good as the water in bottles or streaming out of a filter.
"Assuming that the [tap] water satisfies all health and safety codes for the community, yeah, it's perfectly fine," says Dan Heil, a professor of health and human performance at Montana State University.
U.S. tap water is regulated by the Environmental Protection Agency, which sets safety thresholds for the amount of microorganisms, chemicals and other contaminants in the water. "In general, the drinking water quality in the U.S. is very good," says Stuart Batterman, a professor of environmental health sciences at University of Michigan.
Of course, there are exceptions, the most glaring being the lead pollution of Flint, Michigan's water brought on by crumbling infrastructure and government mismanagement. The toxic effects of lead can be especially troublesome in children, and even low levels of lead exposure have been linked to nervous system damage, learning disabilities, short stature and impaired hearing.
In a situation like that, there are quite a few filters that can remove lead from the water, according to the Environmental Working Group. Back in 2016, NPR created a test you can use to check if you have lead pipes in your home. If you want to investigate the safety of your water further, this tool can show you if your water is in compliance with federal drinking water standards.
But say you live somewhere with safe water and want to run your tap water through a filter before drinking it. All that's really doing, Heil says, is making it more palatable by changing the odor or the taste. There's nothing really wrong with that, he says. If liking the taste of your water makes you drink more, then go for it.
When it comes to health, Tanis Fenton, a registered dietitian and epidemiologist at Cumming School of Medicine at the University of Calgary, says the typical water filter sitting in your fridge won't really do anything. It probably won't even do that much for safety, since she says microbiological decontamination generally requires a sterilization step using UV light or sterilization chemicals.
"Water can be contaminated with bacteria, or viruses, or amoeba ... which would cause disease," she says. "These filters don't do anything to make water safer with respect to those things."
There's also no benefit to taking the naturally dissolved minerals out of municipally regulated tap water, Fenton says.
There actually might even be a bit of a risk if people over-purify their water, says Neil Ward, an analytical chemistry professor at the University of Surrey in the U.K. If you constantly drink sterilized water, your gut flora could become used to that. And then in the off chance you drink water that isn't sterilized, he says your gut could react even more dramatically (and unpleasantly) to microbes or nitrates in the water.
"A lot of that has been brought about because we have become very specialized in removing things from our normal diet," Ward says. "When we are exposed to untreated things, we have reactions to it."
But what about adding minerals like calcium, potassium and magnesium to the water, like the filter from the video? If you're trying to replace all of the minerals from a healthy diet with mineralized water, Heil says it's probably just not going to happen. He says you'd have to drink gallons upon gallons of mineralized water before any health benefits are realized.
"Rather than relying first on some fancy, expensive water, the first thing would be to modify your diet so that you are getting in all of the essential minerals and nutrients that your diet should be able to provide on it's own," he says.
Extra minerals from water won't hurt you, he says, but you'll probably just end up peeing them out if you are already getting enough nutrients in your diet.
Another confusing water option lining the shelves of grocery stores is alkaline water. Alkaline is a fancy way of saying "basic," and this water's pH is a bit higher than standard tap water. Some proponents say this water can neutralize acid in your bloodstream or help prevent cancer and heart disease, but there's not a lot of research to back that up.
Fenton says there are no health benefits to alkaline water, but there have been instances of side effects, like reduced gallbladder emptying and toxic reactions. Baby rats given alkaline water even showed low body weight and cardiac problems.
"Those things are really worrying," Fenton says. "When there's no health benefits, it's really questionable why anyone would want alkaline water."
Water, just like cars, cell phones and shoes, is a part of the commercial market, says Ward. Purifying or adding minerals to water are ways to convince customers that one product is better than its competitors, even if in reality the only thing that changes about the water is the taste.
People also tend to like the idea of a quick and easy way to take the "healthy" route, says Heil, and buying a bottle of water with minerals in it is easier than uprooting a diet to make it more nutritious.
"Everybody's got to drink," he says. "Water all by itself isn't incredibly sexy, and we're all attracted to sexy new things. With a health outcome attached to it, people like that idea."
Filter manufacturers often use an environmental angle to sell their products, asking their audience to think about all the plastic bottles of water you could stop using if you could just create perfect water in your own home. But cartridges and filters must be replaced, and then disposed of or recycled in some way. For a Brita pitcher, that's every 40 gallons or about every two months that you are tossing out a filter or shipping it off to be recycled into a bike rack or watering can.
At the end of the day, if you are trying to improve your health, help the planet, and save your wallet, filling up a reusable water bottle with tap water is a good way to start.
"Tap water has, I think, become underrated as a source of healthy water," says Heil. Not to mention that it's basically free and creates less waste than the alternatives.
But water filter manufacturers urge a cautious approach. Faebian Bastiman, the chief technical officer of the high-tech water filter company Mitte, featured in the video mentioned above, argues that the water delivered to your house only has to legally comply with not having "significant amounts of bad stuff in it." He also says municipal governments don't regulate the pipes inside your house or apartment complex. Having a filter, he argues, could be a last line of defense if there's something gross hanging out in those pipes.
However, the University of Michigan's Batterman notes that water utilities design and operate their systems to maintain a residual level of disinfectants to be in the water at the tap that should prevent microbial growth or biofilms. A water filter should only provide the last treatment or "polishing," he says.
And at the end of the day, the most crucial thing is to actually drink water and help your body stay hydrated.
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