What's in the Water You Buy?

In the United States alone, more than 600 domestic and imported brands of bottled water are now available.

Surprisingly, market research shows that the top reason people buy bottled water is taste, followed by safety and convenience. However, if your tap water consistently meets federal and state drinking-water standards, there's no safety reason to use bottled water. In fact, 25 percent of bottled waters sold come from municipal supplies.

Moreover, last year, the Food and Drug Administration tightened the quality standards for bottled water, requiring it to be monitored and tested in the same rigorous manner that tap water has been for years. The FDA also narrowed the definitions for terms such as mineral, spring and artesian to create a single standard for the entire country.

To understand what these terms mean and to find out what's in the top 10 selling brands, click on the table below.

What the terms mean:

pH: A measurement of water acidity. Perfectly neutral water measures 7.0. More acidic water is less than 7; more alkaline water is greater than 7.

Total Dissolved Solids (TDS): The TDS number measures the content and level of naturally occuring salts and minerals, such as sodium chloride, calcium, magnesium, and potassium in the water. Because the taste of every bottled water is determined by the unique amount and combination of these elements, this makes the TDS a good indicator of taste, says Jennifer Levine, Director of Communications at the International Bottled Water Association. The lower the TDS level, the lighter the taste. For example, if you like the taste of Evian, which has 309 TDS, you may also like other bottled waters with high TDS levels.

While many people believe that mineral waters (which boast the highest TDS — more than 250 parts per million), have medicinal or curative powers, it is still a matter of debate. If you drink enough of it, there certainly is some nutritional value, Levine says, but you shouldn't be looking at water — whether it be a mineral water, artesian or springwater — as your main source of minerals. The number one reason to drink water, she says, is for its hydrating affect on your body.

Springwater derives from an underground source that flows to the surface through a natural orifice.

Artesian water is pumped to the surface from a confined aquifer (an underground layer of water, rock or sand).

Mineral water contains no less than 250 parts per million of naturally occurring minerals, such as calcium, magnesium and potassium. The minerals must come from the water's source and cannot be added later. So while Evian's label indicates that it's a springwater, it is technically a mineral water, too. Perrier is also considered a mineral water.

While not listed in the table, the following are also common types of bottled water:

Purified water has all minerals and other solids removed. It can also be called distilled water, deionized water or reverse osmosis water depending on the removal process. Sparkletts bottles a purified water in addition to its popular artesian brand.

Sparkling water is naturally carbonated and contains the same number of bubbles after treatment that it had when it emerged from the source. (Note: Soda, seltzer and tonic waters are considered soft drinks, not bottled waters, because they do not come from a specific source and may contain sugar and calories. Bottled water also is not allowed to have any caffeine.) Some bottlers of sparkling water include Perrier, San Pelligrino, Ice Mountain, Poland Spring and Quibell.