It's often said that water is the essence of life, and is it any wonder? Seventy percent of the earth's surface is covered in water, and the human body is composed of approximately the same percentage of H2O. Along these lines, millions of Americans rely on tap water every day to quench their thirst, regulate their body temperature, and stay hydrated.

But while water is a necessity for all living things, it's such a ubiquitous resource that we often take it for granted—until we hear disconcerting reports about its safety. Most recently, a five-month Associated Press investigation detected trace amounts of pharmaceuticals in the drinking water supplies of 24 major metropolitan areas, leaving Americans to wonder whether their tap water is really safe after all.

All Tapped Out?

According to experts, tap water is generally safe, but like most things in life, it does come with certain risks. In rare cases, those who drink tap water could experience health complications or be exposed to more chemicals than they bargained for.

  • Pharmaceutical drugs.

    The drinking water supplies tested in the Associated Press report contained a variety of pharmaceutical drugs, including antibiotics and medications for pain, high cholesterol, asthma, epilepsy, mental illness, and heart problems. How did it get there? People take pills, their bodies absorb some of the drugs, and the rest is flushed down the toilet. Because water plants don't test for or remove the residue, trace amounts make their way into the drinking supply. Although many experts believe these findings don't pose immediate health risks, more research is needed to determine the long-term effects, and many environmental agencies are pressuring the U.S. Environmental Protection Agency to set stricter standards.

  • Problems with purity.

    If the pipes in or leading to your home were constructed before 1987, they may leak copper or lead, which can't be monitored or filtered by your area's water supplier. If you suspect your pipes may be a problem, find the pipe leading to the kitchen tap, and follow it as far as possible until it exits your home. Unpainted lead pipes are usually dull gray and soft, while copper pipes are a bright coppery brown color and may be surrounded by silvery metal. In addition, try to find a location where the supply line is accessible, such as the water meter, and check for indications. Be sure to contact your supplier about your concerns and to conduct further testing.

  • Illness.

    The Centers for Disease Control and Prevention (CDC) reports 30 to 40 outbreaks of waterborne diseases from viruses, bacteria, and parasites each year--about half of which can be attributed to contaminated drinking water. While a few of these outbreaks are serious, most result in minor problems, such as fever and diarrhea. In addition, the CDC reports that endemic waterborne acute gastrointestinal illness (AGI) associated with consumption of public drinking water affects from 4 to 12 million Americans annually. Although water filters can't eliminate all of the risks, according to the CDC, reverse osmosis filters can provide some protection against cryptosporidiosis-a diarrheal disease caused by microscopic parasites of the genus Cryptosporidium.

  • Chlorine.

    Virtually all municipalities use chlorine to purify water. And while experts are quick to point out that the benefits of pretreatment with chlorine far outweigh the risks associated with no treatment, it can post potential health risks. Studies have linked high levels of chlorine byproducts to an increased risk of miscarriage, and some experts believe that it can even increase your cancer risk. If you want to play it safe, do your research on the various kinds of water filters available; certain types, such as granular activated carbon (GAC) filters, may be effective in removing chlorine.

Water Wars

Considering all of the potential risks associated with tap water, you may think it's better to invest in the bottled kind. In fact, a 1999 survey from the American Water Works Association Research Foundation found that 56 percent of Americans who drink bottled water do so because they're afraid their tap water isn't safe. However, many experts believe that bottled water presents more health risks than the water that comes from their faucets. Here, the benefits of sticking with tap water.

  • Stricter regulation.

    Municipal tap water may go through hundreds of tests a day. In addition, it's overseen by the U.S. Environmental Protection Agency, which has more regulatory oversight than the U.S. Food and Drug Administration, which oversees standards for bottled water. According to a 1999 report from the Natural Resources Defense Council, the FDA tests water from bottling plants less frequently (about once a week), and its criteria for bacteria and parasites in bottled water are much more lenient than the criteria for tap.

  • The price is right.

    Gallon for gallon, bottled water costs more than gasoline—and in some cases, you're paying for little more than the bottle itself. In fact, at least 25 percent of bottled water is nothing more than processed tap water. While beverage companies aren't legally required to disclose the source of their water, you can assume that if the label doesn't explicitly say "spring water," it comes from the same source as tap water.

  • It's more eco-friendly.

    According to experts, it takes three to four times the amount of water contained in a 20-ounce bottle to make the plastic for the empty bottle. And just consider the amount of carbon dioxide released in transporting those bottles to the store. In addition, although the bottles may be recyclable, the Container Recycling Institute estimates that less than 20 percent of them are actually recycled. The rest eventually make their way into landfills, where they could remain for hundreds of years.