A lot of things about bottled water are hard to explain, starting with why Americans spend $16 billion per year for something they can get from their kitchen sink. The thing that really sets those cash-register bells ringing is the idea that bottled water is healthier than tap water. However there are reasons to question that belief, from hormone-like chemicals leaching from the bottles to the acidity of the water itself. In fact, some bottled water—including the two best-selling brands in America—are about 10,000 times more acidic than tap water.
How is that possible?
Acidity and its opposite, alkalinity, are measured from 1 to 14 on the pH scale. Numbers lower than 7 are acidic, and those above 7 are alkaline. Tap water generally has a pH between 6.5 and 8.5, as does the water in healthy streams and lakes.
We tested pH levels in our review of the best bottled waters and discovered that four of the 13 brands we analyzed, including best-selling brands Dasani and Aquafina, have a pH of 4. Coincidentally, that’s the same pH level as acid rain. If you emptied those bottles into your fish tank, you’d have a lot of dead fish.
The pH scale is logarithmic, meaning each full number on the scale represents a ten-fold increase (or decrease) in acidity. Say you live in Houston and your tap water has a pH of 8. Water with a pH of 7 will be 10 times more acidic than your tap water, and water with a pH of 6 will be 100 times more acidic. Now take a bottle of water with a pH of 4. It’s 10,000 times more acidic than your city water.
That’s a middle-of-the-road scenario. Some city water has a lower pH—the EPA recommends a range of 6.5 to 8.5—and not all bottled water is acidic. So maybe that bottle of Dasani is only about 1,000 times more acid than the stuff you get from your tap. Then again, it may be more. Some bottled waters have a pH as low as 2.82. Compare that to the tap in Boston, where city water has a pH of 9.6. Now you have a bottle of water that is more than one million times more acidic than the city stuff.
Balance is Everything
The acidity of bottled water is something to be aware of because we drink so much of it. Last year Americans drank an average of 39.3 gallons of bottled water, a figure that surpassed soft-drink consumption for the first time. That’s a good trend because any kind of water is better for you than soft drinks, which tend to be even more acid than bottled waters (Classic Coke has a pH of 2.37) and are loaded down with sugar or potentially harmful artificial sweeteners.
If nearly 40 gallons per person sounds like a lot of water, consider that the majority of Americans drink bottled water occasionally or not at all. So those who do drink bottled water regularly consume an awful lot of it. Health professionals recommend we drink eight glasses of water every day. That adds up to half a gallon per day, or 182.5 gallons a year—which would set you back $222 per year if your favorite brand sells for the national average of $1.22 per gallon. If you insist on the most expensive water that doesn’t come in a solid gold bottle, you’d shell out a little more than $422,000 a year. Maybe we should stick to the popular brands.
The top picks in our bottled water review all had a fairly neutral pH between 7 and 8, which is close to the pH level our bodies naturally maintain. Human blood pH clocks in at a just-barely-alkaline pH of 7.35 to 7.45. If we deviate more than about half a point from that in either direction, we die. So medically speaking, pH balance is a big deal.
Fortunately, our bodies maintain their pH balance no matter what we eat or drink. In fact the first place water goes when you swallow it is a highly acidic biological cauldron known as the stomach, where the pH hovers around 3. As soon as that acid soup leaves your stomach the body neutralizes it, says Prof. Marion Nestle of New York University, who holds a PhD in molecular biology and has written nine books on nutrition and the politics of food.
“It’s hard to talk about this without sounding wonky but the body has phenomenal buffering capacity,” she says. “The acid is quickly neutralized once it gets out of the intense acidity of the stomach, so not to worry.”
The problem, according to many holistic health practitioners and some medical researchers, is the lengths to which our bodies must go to keep that balance. When the system becomes too acidic, the body absorbs alkaline minerals from bones, organs and tissues to compensate. A highly acid diet may contribute to osteoporosis, as the body pulls calcium from the bones to regulate acidity and later excretes it in the urine. One study found that over the course of 20 years on a typical modern diet, a person could pee away almost half their skeletal mass of calcium.
“There is some literature to say that there may be some leaching of calcium from the bone or even development of kidney stones if there’s more acidity in the diet,” says registered dietician Vicki Shanta Retelny, a popular nutrition blogger and author of The Total Body Diet for Dummies.
According to naturopathic physician and health-product pitchman Dr. Josh Axe, acidity contributes to a host of chronic health problems, from allergies, asthma and headaches to frequent colds and joint pain. Over the long term, he’s written, chronic acidosis can lead to arthritis, cancer, diabetes, fibromyalgia and heart disease.
Not all bottled water brands are equal
So it follows that we should avoid consuming too much acidic food, and that includes steering clear of low-pH bottled water—especially at two bucks a bottle. But it’s not quite that simple. First, those chronic health problems are linked to a diet that’s bad for you in all kinds of ways; acidity is just one of them. And the scientific literature has very little to say about how the acidity of the water we drink—as opposed to the foods we eat—affects our internal pH balance.
“My number-one piece of advice is that you should be getting your nutrients from food first, and the alkalinity or acidity of water is not going to affect your pH as much as your body’s own mechanisms,” Retelny says.
The Bottom Line
So is low-pH bottled water bad for you? The answer depends on whom you choose to believe. No one in the medical establishment seems the least bit concerned about it, which may be why they haven’t produced any definitive research on the subject. Holistic practitioners take a much dimmer view of low-pH bottled water. Almost all of them echo Retelny’s advice that the pH of the water you drink is much less important than eating a balanced diet.
One of the best reasons to avoid acidic water—and other low-pH beverages like soda, energy drinks and fruit juices—is to prevent tooth decay. It’s not just the sugar in those drinks that causes cavities. Acidic liquids have a corrosive effect on teeth, and sipping a low-pH beverage—even water—all day is akin to giving your teeth a constant, low-level acid bath.
Considering how much water we drink it’s a good idea to be aware of the issue, and know the pH level of the water you choose. In our review of the best bottled water we tested the acidity of 13 leading brands, and discovered that the low-pH brands scored consistently lower in the taste test. Our top pick, Resource Spring, had a pH of 7.5, and runner-up Fiji clocked in at 8. The worst performer? Dasani, with a pH of 4. In general, our testers preferred waters with a neutral pH.
If you worry about the health effects of drinking acidic water you’re probably also concerned about chemical residues from plastic bottles, not to mention their effect on the environment. Most disposable water bottles are made from a lightweight plastic called polyethylene terephthalate, or PET. While it’s fully recyclable and ubiquitous throughout the food industry, it may also leach endocrine disruptors, particularly over time and when exposed to heat, such as in a hot car or storeroom.
Tap water has its own problems with contaminants. Just ask anyone in Flint Michigan, where corrupt and incompetent officials cut corners in the city water system, ultimately exposing thousands of people to extremely harmful levels of lead. Thankfully, Flint was an isolated incident and the vast majority of municipal water districts in the United States supply clean, safe water. A host of home filters make it easy to remove additives frequently found in city water, such as fluoride, chlorine and volatile organic compounds. So in general, tap water is as safe as bottled water, and may be healthier.
Those are two different things, safety and health. Bottled water is safe for reasons that may render it less healthy. Regardless of where bottlers source their water (about 45 percent get it straight from municipal taps) they take extreme measures to filter out impurities and kill harmful parasites. Purifying techniques like reverse osmosis and distillation make the water sterile and therefore safe, but can also remove minerals that our bodies are accustomed to getting from water.
That brings us to why some bottled waters are so much more acidic than tap water, or for that matter water from streams, springs or wells. The minerals removed by extreme filtration are the same minerals that make the water they’re dissolved in less acidic. That explains why some bottled waters can be 10,000 times more acidic than the stuff that comes out of your kitchen sink.