How we tested
It is rather baffling that a substance as fundamental and as abundant as water can form the basis of an astonishingly large business, and sales and consumption of bottled water are only expected to grow further. To meet the demand, retailers have stocked their shelves with a multitude of brands, both domestic and foreign, many donning labels that suggest pristine alpine springs or crisp, clean mountain air. That the bottles differ in labeling is clear; what is less apparent is the extent to which they differ in taste. To better understand what—if anything—distinguishes one bottled water from another, we conducted a blind tasting.
We arrived at nine brands that covered the still-water spectrum—both domestic and imported. We also included a water not expressly meant for drinking, ultrapure plasma-grade water. Used in sensitive chemistry applications, this water is double-distilled and virtually free of all minerals and impurities. We reasoned that by including in the tasting water in its near-purest form, we might gain some insight into what makes water taste good—purity or impurities, in a manner of speaking.
Bottled Water Primer
There are several types of bottled water, but three categories stand out: spring water, artesian water, and purified water. A bottle labeled "spring water" must contain water that came from an underground water formation that flows naturally to the earth's surface. The location of the source must be identified. The water is collected either at the spring or through a hole that has been made to tap the source that feeds the spring. Spring water is sometimes bottled without additional treatment (this is particularly true of European bottled waters), but domestic bottlers often use carbon filtration to remove odors, micro- or ultrafiltration to remove fine particles and impurities, and/or ultraviolet light or ozonation to disinfect the water.
Some producers tap several springs, bottle each separately, and yet sell all under the same brand name. This means that a bottle of brand X purchased on the East Coast may not be from the same source as a bottle of brand X purchased on the West Coast. This practice is common among domestic producers and better allows suppliers to meet demand and minimize the cost of transport. But it also means that the flavor profiles of the same brand may differ from one region of the country to another. Many European and foreign producers bottle water from a single source—and are proud of it. Of the nine brands we assembled for our tasting, six were spring waters.
Artesian water differs from spring water in that its source must be an underground formation known as a confined aquifer. The water is sandwiched between—or confined by—a top and bottom layer of impermeable rock. When the aquifer is tapped, natural internal pressure causes the water to flow. Is artesian water better than "regular" spring water? Not necessarily. While the U.S. Environmental Protection Agency says that water from artesian aquifers is often cleaner because the confining layers of rock and clay impede the movement of contaminants, there is no guarantee that artesian water is any more pure—or otherwise better—than spring water. We included only one artesian water in the tasting.
Spring water and artesian water both contain dissolved solids (or minerals) such as calcium, magnesium, sulfates, silica, and chlorides. Mineral water is spring or artesian water that naturally contains at least 250 parts per million (ppm) of total dissolved solids (TDS); we included one mineral water brand.
Two purified waters were part of our tasting. What is purified water? The simple definition is that purified water has been processed to remove contaminants and minerals before being bottled. The source is often a municipal water supply; the water is then filtered in a process called reverse osmosis, removing most of the impurities and leaving the water nearly bereft of minerals. Such a tight filtration process means that no matter what the source, the taste of purified water is likely to be consistent from bottle to bottle. One of the purified brands we tested added minerals back to the purified water to obtain optimal taste; the other did not.
By contrast, a spring water's flavor profile is organically derived. As the water journeys from its origin as rainwater or snowmelt to the spring, a process that can take years, it travels through layers of rock, clay, gravel, and/or sand that filter out impurities. As the impurities are filtered out, the water also acquires dissolved minerals that in their specific combinations give the water its signature flavor.
What It Boils Down To
The only water that tasters unanimously rejected was the ultrapure plasma-grade water, which earned the lowest possible score because of its flat, vapid flavor. Though this water is of course unavailable to consumers as drinking water, it did teach us something. Ostensibly, when it comes to water, absolute purity is a liability, not an asset. Some mineral content makes water likable.
Is spring water better than purified municipal water? The two purified waters we sampled earned respectable scores, coming in fourth and fifth, and beat out four spring waters. But they were not in the winners' circle. Two spring waters and the one artesian water in the tasting swept the pack, with win, place, and show.
What should you buy? Our results show that the flavor differences between bottled waters are not great. Unlike the differences between brands of chocolate or barbecue sauce, the distinctions between brands of bottled water are so modest that you are unlikely to be disappointed with any of those that we tasted.