A glass of tap water. (Maddie McGarvey/For The Washington Post)
Columnist, Food

For once, I'm ahead of the curve! I've been drinking raw water all my life.

I know what you're thinking. "Aha! She drinks raw water! That's why she's such a remarkable thinker, with such penetrating insight on so many issues!"

Okay, maybe not.

My raw water consumption was an accident. In the Cape Cod town where I spent my childhood summer vacations, the tap water tasted terrible, but there was a bubbler right outside the town hall, gushing a constant stream straight from an underground spring. Like other locals, my family had a motley assortment of jugs that we regularly filled from it, and I still occasionally use it.

I never imagined that raw water — spring water that hasn't been treated at all — would have a moment, but having a moment it is. The New York Times seems to have started it by running a story about purveyors of raw water and the people who pay through the nose to drink it. In the subsequent media pile-on, outlet after outlet dissed the ideas behind the trend and the first-world naturalniks who signed on.

One aspect of the trend that came in for particular ridicule was the idea of "live water," a claim made by a company called, go figure, Live Water. The company touts the living things in its untreated water. Those things are bacteria. Only the company doesn't call them "bacteria." It calls them "probiotics."

Now, examining the claim that there are probiotics in spring water is the fact-checking equivalent of shooting fish in a barrel. I certainly couldn't find a shred of evidence that the bacteria found in Live Water can do you any good (and my request for that evidence went unanswered by the company). Which is not to say they'll do you harm. While there have been a few cases in the literature of infections from those bacteria, they don't appear to be particularly dangerous.

The other purported benefit of untreated water is minerals, which untreated water does indeed contain. For example, water from Tourmaline Spring has 1.6 milligrams of magnesium per liter. Which means that five gallons of the stuff has the magnesium of one banana. Three and half gallons have the calcium in one serving of Greek yogurt. But there are waters that have enough minerals in them to make a meaningful contribution; if minerals are your concern, pick those. San Pellegrino, for example, has about 20 times the calcium and 30 times the magnesium of Tourmaline Spring water. (There are also minerals in tap water, although levels vary and it's hard to find out what yours has.)

So, is there anything particularly health-giving about untreated spring water? No. There isn't. But that doesn't mean we should sound the alarm bells about its safety. Drinking spring water isn't like dipping your cup in the stream behind your house; it's bottled before it has much chance to get contaminated by chemicals or leached lead or drug residues or duck poop, and the FDA requires it to be tested.

But I think the biggest reason that people are willing to pay $6 a gallon for water that comes straight to them from deep in the earth's bowels is that they are suspicious of the water that comes straight to them from the kitchen faucet. It's the chemicals and the drug residues and leached lead and the duck poop.

And the fluoride.

Fluoride was first added to water in the United States in 1945 (in Grand Rapids, Mich.) for cavity prevention. And early studies comparing rates of cavities in fluoridated vs. non-fluoridated towns showed a huge improvement — about a 50 percent drop. Since then, though, other sources of fluoride (like toothpaste) have decreased cavity levels overall, and recent studies of the value of fluoridation are much less compelling. A 2015 review of the evidence, by the well-respected Cochrane group, concluded that most of it wasn't very high-quality, making it difficult to draw conclusions. This doesn't mean that fluoride doesn't help prevent cavities; it does. But, the lower the rate of cavities in the population — because of fluoride in toothpaste, or supplements, or mouthwash, or diet, or perhaps just because of better dental hygiene — the smaller the benefit from fluoridated water. At some point, the benefit becomes so small that it's not worth the risk.

Ah! The risk. While a well-documented downside is that fluoride can cause fluorosis, a discoloration of tooth enamel, that's generally not what gets people's attention. An exhaustive review of the evidence by the National Academies of Science in 2006 concluded that there's at least some evidence that high levels of exposure can affect reproductive systems and fertility, the endocrine system and thyroid function, and possibly even intelligence. Those are the risks that make people sit up and take notice.

The key here, as it so often is when we're talking about toxicity, is the dose. At high doses, fluoride may present risks, which is why the Environmental Protection Agency sets an upper limit for the amount allowed in drinking water. The National Academies report recommended lowering that limit, which is 4 milligrams per liter, but the EPA has not.

At lower doses, fluoride can help prevent cavities, which makes fluoridation a Goldilocks problem — getting the level just right. Several public health groups pin that level at 0.7 milligrams per liter, the level now recommended by the Department of Health and Human Services.

But how about the chemicals, the leached lead, drug residues and the duck poop? We don't have to look any farther than the crisis in Flint, Mich., to know those risks are real.

A study by the Natural Resources Defense Council found that, in 2015, about 1 in 5 Americans was served by a system with at least one violation — either a contaminant in amounts over the limit or a failure to test. (You can check your local water status with the EPA or the Environmental Working Group.) How much of a risk does that pose?

According to Tom Neltner, chemicals policy director for the Environmental Defense Fund, it depends on the violation. For many contaminants, risk is based on chronic exposure, and a single violation isn't an indication that the water is unsafe but "an indication that the utility isn't doing all it should to make it safe." If there's a serious safety problem with your water — "imminent and substantial," Neltner said — the state and the utility are required to act.

If you're concerned about your water, Neltner suggests checking the Consumer Confidence Report that water utilities are required to issue to their customers every year; it will tell you your water source and the level of contaminants. If you don't have your report (you mean you don't always read every word that comes with your water bill?), contact your local water provider. And if you want a cheap insurance policy, use a water filter — it'll remove some, although not all, contaminants.

Amid all the uncertainty, there is one thing we know for sure: Bottling and transporting water uses energy and burns fossil fuels. On the greenhouse gas front, bottled emits up to 32 times (depending primarily on how far it's shipped) the CO2 of tap, according to a University of Michigan analysis. Your (16-ounce) bottle-a-day habit is the carbon equivalent of driving between 56 and 224 miles per year, which means that bottled water isn't Enviro Enemy No. 1 — it's just a really easy place to curtail your impact, since there's an alternative right there in your kitchen, practically free.

For some of us, some of the time, tap water quality is an important issue. For most of us, most of the time, it isn't. I happily drink the water coming out of my tap. I also happily drink the raw water gurgling up a few miles down the road. Mostly, I'm grateful to live a life where the quality of my water doesn't have to be one of my concerns.