People obtain their daily water supply from different sources. For many years, tap water has been the primary source of water for most people in the United States. For more than 50 years, water has been fluoridated in ever-growing numbers of communities.

Fluoridated water contains levels of fluoride added to the water within the limitations set by federal regulations. Before fluoridation of water, tooth decay was much more prevalent. Adding fluoride to drinking water, toothpaste, and mouth rinses has helped to prevent cavities in many people. In children under five, too much fluoride can cause a disruption in enamel formation (fluorosis), so careful monitoring of ingested fluoride products should be performed.

Although most community water supplies now contain fluoride, in recent years increasing numbers of Americans have begun to get their daily water from sources other than the tap. Such sources include bottled water, water machines at work and water that is filter treated at home. In many cases, these alternative sources of water do not offer the same fluoridation benefits as tap water.

People can choose from a wide array of available bottled water. The water source differs from brand to brand and is listed on the water’s packaging. The word “natural” is only allowed for bottled water that is derived from springs or wells without altering the original composition of the water through a treatment process. The following are some examples of different bottled water sources:

• Artesian well water. Comes from a well that taps a confined aquifer (a water-bearing underground layer of rock or sand). It is usually collected without mechanical pumping.
  
  
• Mineral water. Contains minerals at a standard level of no less than 250 parts per million (ppm) of total dissolved solids or minerals. These minerals must be naturally present and not added to the water.
  
  
• Spring water. Comes from an underground source and naturally flows to the surface. Spring water must be collected at the spring or through a borehole tapping the underground formation feeding the spring.
  
  
• Well water. Collected from an underground aquifer with a mechanical pump.

The U.S. Food and Drug Administration (FDA) does not consider sparkling water, seltzer water, soda water, tonic water or club soda to be types of bottled water.

In some cases, regular tap water is sold in bottled form after it has been treated. This water is typically referred to as purified water and has been processed or “purified” to remove minerals and other solids or impurities. The water can be purified by a number of different methods, such as:

• Absolute 1 micron filtration. Water flows through filters that remove small particles, such as parasites.
  
  
• Distillation. Water turned into steam and condensed into pure water, removing impurities and reducing levels of all chemicals, including heavy metals such as lead. Due to its purity, distilled water is used in manufacturing of pharmaceuticals and liquid prescriptions. One of the removed chemicals from distilled water is fluoride.
  
  
• Ozonation. Use of an antimicrobial agent called ozone gas to disinfect water. This technique is used instead of chlorination, which can leave a residual taste and odor in the water.
  
  
• Reverse osmosis. The water is forced through membranes to remove minerals.