How Bottled Water Works

Woman Pulling Bottled Water from Supermarket Shelf
The bottled water industry is an $8 billion plus industry. Oscar Wong / Getty Images

For a natural resource that most of us have access to for minimal cost, water is doing pretty well as a revenue generator. The bottled version of the stuff is currently an $8 billion industry in the United States alone, with Americans drinking about 7 billion gallons of it in 2005. That's compared to hundreds of billions of gallons of tap water, but for a product that can cost up to 10,000 times more than its municipal counterpart, it's still an impressive marketshare.

So what's the appeal? The three most common reasons given by bottled-water drinkers are healthiness, purity and taste. As we'll get into later on, the first two reasons are somewhat misguided, and the third is open for debate. For a seemingly basic food product, bottled water has generated its share of controversy. Some of it focuses on the federal and state regulations governing the industry, some of it goes deeper into the ecological implications of bottling and transporting billions on billions of gallons of something that flows freely from the tap, and some of it calls into question the labeling practices of bottled-water companies.


­ The pretty pictures and superlative language on the labels of bottled waters can sometimes be misl­eading. One famous example is the now defunct Alaska Water, which stated on the label, "Alaska Premium Glacier Drinking Water: Pure Glacier Water From the Last Unpolluted Frontier," and came from one of the municipal water supplies in Juneau. The currently available Glacier Clear Water comes from a source in Greeneville, Tennessee. But if you look past the names and descriptions and go straight to the water type, the label will more or less tell you what's in the bottle. "Spring water" and "artesian water" are examples of bottled-water types.

Aquafina and Dasani, the two top-selling brands in the United States, are "purified drinking water." Other popular brands, including Poland Spring and Arrowhead, are "spring water." Evian is "mineral water," and Perrier is "sparkling mineral water." Eldorado Springs is "artesian spring water." These labels primarily indicate two things about the water in the bottle: its source and any treatment it has undergone. In the next section, we'll examine the sources and treatments associated with each type of bottled water and take a look at the process Aquafina uses to produce its "purified drinking water," which starts out as plain old tap water purchased from public water supplies.



Behind the Labels

You can usually figure out what's in a bottle of water by the stated water type -- the FDA regulates the use of terms like "spring water" and "purified water." There are six primary bottled-water types, and several more variations that combine a couple of the basics:

  • Artesian water: Artesian water comes from an artesian well, which draws water from a confined aquifer (an underground, porous rock or sand formation that bears water and is under pressure from a layer of rock or clay above it). The pressure from the confining layer forces the water from the aquifer upward. The level of the water supply the artesian well is drawing from must sit above the uppermost layer of the aquifer.
  • Mineral water: Mineral water is spring water that has at least 250 parts per million (ppm) of total dissolved solids (TDS) in it. These "dissolved solids" are minerals like calcium, magnesium, sodium and potassium, and they must be present in the water at the source, not added later. By contrast, regular spring water typically has about 50 ppm of TDS.
  • Naturally sparkling water: Naturally sparkling water comes from a spring or artesian well and has natural carbonation in it. The carbonation may be removed during processing and then replaced, but the carbonation levels after replacement must be the same as the level of carbonation at the source.
  • Purified water: Purified water comes from either a protected underground source or from a municipal drinking-water supply (public tap water). It has been "demineralized" -- treated by one or more of several processes to remove dissolved solids. If the water comes from a municipal water source that uses chlorine as a disinfectant, the manufacturer may further treat the water to remove the chlorine.
  • Spring water: Spring water comes from a protected, underground water source from which the water flows to the surface on its own. It may be collected either at the surface spring or through a sanitary, protected hole drilled directly into the source feeding the spring. If the water is collected through a hole drilled into the source, it has to have exactly the same composition as the water in the surface spring.
  • Well water: Well water is drawn from a protected well that taps directly into an unconfined aquifer.

Of the basic types of bottled water, the only one required by definition to undergo further treatment once it's drawn from the source (or purchased from the municipal water supply) is purified water. The most common treatment processes for purified water include:


  • Filtration: The water is sent through filters or membranes whose holes will only let through extremely small particles, typically those smaller than 1 micron. Contaminants larger than 1 micron, including many germs and inorganic solids, can't make it through.
  • Distillation: The water is vaporized. Since minerals don't vaporize, all that's left after the vapor recondenses is demineralized water.
  • Reverse osmosis: The water is forced through semipermeable membranes not porous enough to let minerals or other contaminants through. For more in-depth information, see How does reverse osmosis work?
  • Ozonation: Ozone gas (the same type found in the atmosphere), typically created by subjecting oxygen to electrical current, is an antimicrobial agent -- it kills microorganisms. The water is infused with ozone (03) molecules as a disinfecting process, and the molecules naturally break down and leave the water fairly quickly. As an additional benefit, when the ozone molecules degrade to 02 and molecules, this leaves free oxygen ions to bond with other contaminants like iron and sulfur. When the oxygen bonds to these molecules, it turns them into oxides, which are insoluble. These now-insoluble contaminants are then filtered out.
  • UV-light treatment: Ultraviolet (UV) light is a disinfecting agent -- it kills microorganisms, including bacteria and viruses, although some microorganisms are less affected by it than others. The process uses no chemicals. Instead, the water is subjected to intense UV light inside a chamber. The UV light damages microorganisms at the cellular level, either killing them or causing them to lose the ability to replicate. A virus that can't replicate is harmless.

Aquafina is an example of purified drinking water. It begins as municipal tap water and then undergoes a treatment process that Aquafina calls the "HydRO-7(tm) purification system."

According to Aquafina, what's left is actually 4 parts per million (ppm) of total dissolved solids -- still significantly less than the FDA regulation stating that purified water should have no more than 10 ppm of TDS.

In the next section, we'll examine some of the regulations affecting bottled water and find out how they compare to EPA standards for tap water.


Bottled-water Regulations

The FDA (U.S. Food and Drug Administration) regulates bottled water as a packaged food item. FDA regulations for bottled water are more lax than the EPA (U.S. Environmental Protection Agency) regulations for municipal drinking water.

FDA regulations for bottled-water safety start with the most basic regulation for all food products -- bottled water must be packaged in a sanitary container and in a sanitary environment. Beyond the basic rules for packaged food, the FDA has specific rules for bottled water. First, it must come from an approved source, which doesn't mean the FDA goes and checks the source to make sure it's safe. It simply means the water must come from one of two places: a protected natural source, such as a spring or artesian well in which measures have been taken to assure against contamination by surface water; or a municipal source of drinking water (i.e. tap water). The FDA also has rules about how companies can label their bottled water. For instance, they are not allowed to flat-out lie about the water's source, and if the water originally came from an untreated municipal water source (water that wasn't potable when they bought it), they have to disclose that on the label. They also have to disclose if they have added anything to the water, such as fluoride or other minerals.


Other FDA bottled-water regulations determine the maximum levels of certain contaminants allowed, including organic (bacteria, viruses, parasites) and inorganic (radon, lead, arsenic). These regulations are based on the EPA's requirements for tap water, but there are differences. The FDA does not consider bottled water to be a risky food product for at least a couple of reasons: First, since the water's source must be protected in the first place, the water shouldn't be susceptible to many of the harmful contaminants found in surface and ground water, which municipal systems sometimes have to deal with; and second, there have been no instances to date of significantly contaminated bottles of water. There are contaminants in bottled water just like there are in tap water, but no testing has uncovered levels that would pose a health risk. So the FDA does not regulate bottled water as tightly as it regulates, say, prescription drugs.

In some areas, FDA regulations are actually stricter than the EPA's rules for tap water, as in the case of lead. Tap water, which travels through lead pipes to get to your faucet, is allowed to have up to 15 parts per billion (ppb) of lead by necessity, whereas bottled water can't have more than 5 ppb. But in most cases, the EPA standards for tap water are harder to meet. For example, whereas tap water is not allowed to contain any E.coli or fecal coliform bacteria at all (E.coli can cause illness, and fecal coliform can indicate the presence of disease-causing agents), bottled water is allowed to have trace amounts of these contaminants. Still, there have been no confirmed instances of finding either bacteria in any brand of bottled water, lending credence to the FDA's assertion that the risk is low. Also, cities must disinfect all potable water supplies and test for asbestos and parasites, while there are no matching FDA requirements for bottled-water companies.

At one level down from federal regulation, which only affects water that travels between states, there is state regulation of the industry. Many states have bottled-water regulations that are stricter than the FDA's, requiring bottled-water companies to obtain a yearly license and submit to regular inspection of water sources and treatment facilities. Some states don't regulate bottled water at all.

By far the tightest regulating body overseeing the bottled-water industry is the industry itself, most notably in the form of the International Bottled Water Association (IBWA). The IBWA enforces voluntary self-regulation of its members, who produce about 80 percent of the bottled water purchased in the United States. IBWA members must meet the requirements set forth in the IBWA Model Code, which includes disinfection in the form of reverse osmosis, filtration or distillation for any water drawn from a municipal drinking water source. (Companies using protected, natural sources are not required to disinfect the water.) IBWA members must also submit to an unannounced facility inspection once a year by a third-party organization. One independent group that tests bottled water for quality and compliance is the National Sanitation Foundation (NSF), which runs a voluntary Bottled Water Certification Program that includes water-source and plant inspection and the testing of both water (for contaminants) and container-sealing processes. See the NSF Product and Service Listing for a list of NSF-certified bottled waters.

You probably noticed a few things in the above discussion of regulations. For one thing, the FDA's and the states' regulations are the only ones that are not voluntary, and some states don't have regulations. So that leaves the FDA. And the FDA's regulations are based on the premise that bottled water is not a potential risk to public health. These are a couple of the points that contribute to the controversy surrounding bottled water. In the next section, we'll take a closer look at the issues.


Controversy: Under-regulation and Misconception

If we re-examine the top reasons people give for drinking bottled water instead of tap water -- taste, purity and healthiness -- the controversies start to become obvious. While the FDA prohibits bottled-water manufacturers from implying that their water is "safer" or "purer" than any other kind of water, implications are a difficult thing to quantify. In any event, many bottled-water drinkers believe they are drinking something that is healthier than tap water.

In reality, all water is "healthy" as long as it doesn't possess high levels of harmful contaminants, which tap water does not. In May 2005, the ABC news program "20/20" sent five different national brands of bottled water and one sample of tap water taken from a New York City drinking fountain to a microbiologist for testing. The lab tested for contaminants that can cause illness, like E.coli. The results showed no difference whatsoever, in terms of unhealthy contaminants, between the bottled waters and the tap water. So perhaps it's a matter of semantics, but the issue seems to be more one of purity than of healthiness: Some bottled waters do contain fewer total dissolved solids than tap water, but most scientists agree that the levels of dissolved solids in tap water are not harmful to human health. And when it comes to dissolved solids, in certain cases and in some opinions, more is actually more. People who drink mineral water presumably are drinking it because they believe the higher mineral count in the water is beneficial to their health. In the case of mineral water, it may just be that the water is healthier than tap water.


On the other hand, an interesting point to note is that many cities add fluoride to their water if it doesn't naturally contain the American Dental Association recommended amount (0.7 to 1.2 ppm) to help keep people's teeth healthy. So people who don't drink tap water may be getting less fluoride than people who do. Dentists warn that this may lead to more dental problems in the long run for people who only drink bottled water that doesn't contain any or enough fluoride (some bottled waters leave the fluoride in or add it as a beneficial mineral after processing). Of course, the healthiness of fluoride-enriched water is forever under debate, so "healthiness" ends up being a somewhat subjective quality. Purity, on the other hand, can be quantified.

If someone is looking for purity, choosing purified water may deliver the goods. With an industry standard of fewer than 10 ppm of total dissolved solids, purified water is pretty close to plain H20. On the other hand, if someone defines "pure" as "safe," we're right back to the healthiness issue discussed above. Bottled water sources are typically tested for harmful contaminants once a week at most. Municipal water supplies are tested hundreds of times every month. Tap water may not be perfectly clear, or it may have a slight chlorine aftertaste, but according to the Minnesota Department of Health, those are merely aesthetic qualities that do not indicate the water is unsafe. And bottled water -- even purified water -- does not have to be completely free of contaminants. It simply has to have below the FDA-allowed and/or state-allowed level of certain contaminants.

So what we're left with is taste. Many bottled water drinkers report taste as the primary reason for their bias -- they just think bottled water tastes better than tap water, end of story. In some cases, this is entirely likely. Since many cities treat their tap water with chlorine to disinfect it, an aftertaste in tap water is pretty common. And some cities' tap water just tastes bad, even though it's perfectly safe, due to higher levels of certain minerals.

But a couple of very non-scientific, blind taste tests have found that most people -- or most people in New York City, to be more accurate -- can't actually tell the difference between tap water and bottled water once they're all placed in identical containers. In one of these tests, "20/20," continuing its tap versus bottled testing, asked randomly chosen people to taste six different waters, five popular bottled waters and New York City tap water, and rate them as either "bad," "average" or "great." The New York City tap water tied for third place, winning over two of the bottled waters. ABC's "Good Morning America" performed a similar test on its studio audience and received comparable results. Probably the most scientific conclusion that can be drawn from these tests is that New York City apparently does a really good job with its tap water. A nationwide taste test might provide different results.

One of the most serious arguments leveled against bottled water relates to federal regulations, or the lack thereof. Some people believe that water bottled for the specific purpose of human consumption should face exactly the same regulations as municipal water intended for human consumption, whether the FDA regards it as a risky product or not. The other main regulatory concern is the fact that FDA regulations only apply to bottled water shipped between states. If a company produces and sells its bottled water with the borders of one state, and that state is one of the 10 or so that does not regulate bottled water, that company's product is subject to no oversight at all. Unless it voluntarily adheres to the rules of a trade organization. Which is, well, voluntary.

Beyond safety regulations and general consumer misconceptions that may or may not be fueled by the marketing efforts of bottled-water manufacturers, the other primary accusation against the industry can be summed up in two words: environmental nightmare.


Controversy: Ecological Effects

In 2004, worldwide sales of bottled water totaled 41 billion gallons. There's a lot of plastic left over once 41 billion gallons of water, much of it in 8- or 12-ounce containers, is consumed.

In a single year, manufacturers around the world use about 2.7 million tons of plastic to bottle water. Most of those bottles are a type of plastic called polyethylene terepthalate, or PET, which is produced from crude oil. To produce bottles to meet yearly bottled-water demand in the United States alone requires 1.5 million barrels of oil. That much oil could power about 100,000 cars for a year, according to the Earth Policy Institute.


And almost 90 percent of bottled-water bottles end up in the trash or on the ground, not in recycling bins. They can take up to 1,000 years to degrade, and when they do, they can leak harmful chemicals into the ground, contaminating ground water -- ironically inducing a new cycle of pollution that means bottled water may actually be a necessity in the United States some day. Some companies, like the Colorado-based BIOTA bottled-water company, are making a concerted effort to reduce their effect on the environment. BIOTA uses a corn-based, biodegradable plastic bottle that can take fewer than three months to degrade in a compost pile.

But lack of recycling isn't the only issue. Of the roughly 10 percent of bottles that do get recycled, most aren't much help in offsetting the energy consumed and pollution produced by the original manufacturing and transportation process. There are so many types of plastics that the containers are extremely hard to sort, so recycling them is very expensive. As a result, a lot of recycling companies in the United States won't do it. Most recycling of plastic bottles ends up happening overseas, particularly in China. Those billions of bottles have to be shipped there, meaning even more energy is consumed to get the bottles to the point of recycling. And once they are broken down for re-use, manufacturers are typically not able to build a bottle out of recycled plastic alone. A "recycled" plastic bottle has far more virgin plastic in it than recycled plastic.

Of course, in parts of the world where potable water is not readily available, bottled water is an excellent option despite any environmental concerns. People need to drink. But when drinking water is drawn from good sources, bottled and branded, shipped to places where potable water is readily available from the tap and consumed by people who have easy access to that tap, it can be argued that a natural resource is being depleted in the name of business. Some towns and villages have reported that within months of a bottled-water company setting up shop in their neighborhood and tapping into underground water supplies, their own wells have run dry. However, because aquifer geology is not an exact science, it's always hard to prove that the bottled-water company is in fact tapping the same source as the community well, so the claims typically go unaddressed outside the environmentalist community.

Whether we'll eventually run out of public water supplies remains to be seen. In the meantime, go to the trendiest restaurant you know and ask the water sommelier which type of water to drink with your salad course. If she says "Evian," ask if she has New York City tap water instead. Evian came in last in that taste test.

For more information on bottled water and related topics, check out the links on the next page.


Lots More Information

Related HowStuffWorks Articles

More Great Links


  • American Water Works Association.
  • Aquafina.
  • "Bottled Water, a natural resource taxing the world's ecosystem."
  • "Bottled Water, Home Water Treatment Systems, and Fluoride Exposure." American Dental Association.
  • "Bottled Water: Pure Drink or Pure Hype?" National Resources Defense Council.
  • Bullers, Anne Christiansen. "Bottled Water: Better Than the Tap?" FDA Consumer magazine. July-August 2002.
  • Fisk, Umbra. "Bottle Racket." Grist Magazine. August 2, 2004.
  • Howard, Brian. "Is America's $8 Billion Bottled Water Industry a Fraud?" E/The Environmental Magazine. December 9, 2003.
  • International Bottled Water Association.
  • "International Bottled Water Association Offers Tips for Proper Bottled Water Storage." IBWA.
  • "NSF Bottled Water Certification Program." NSF International.
  • Owen, James. "Bottled Water Isn't Healthier Than Tap, Report Reveals." National Geographic News. February 24, 2006.
  • "Ozonation in Water Treatment." Wilkes University Center for Environmental Quality.
  • "Plastic Bottles and Water." Ask a Scientist. January 20, 2003.
  • "Researcher Dispels Myth of Dioxins and Plastic Water Bottles." Bloomberg School of Public Health.
  • Stossel, John. "Is Bottled Water Better Than Tap?" ABC News. May 6, 2005.
  • "Types and Treatment of Bottled Water." NSF International.
  • "Water Storage Before Disaster Strikes." American Red Cross.
  • “What’s in that bottle?” January 2003.