Around the World:
Safe water is critical to public health whether it is used for drinking, food preparation, supporting livestock, growing food, or recreation. At a global scale, almost 1.8 billion people use a contaminated source of drinking water, leading to over half a million deaths every year. Contaminated water is well known for transmitting diseases like diarrhea, cholera, and dysentery. However, over longer time scales, water contaminated by industrial and agricultural pollutants can have an even more insidious impact, contributing to disease and damage to the human body that is hard to trace and hard to prove.

In the United States:
While the U.S. is largely protected from diseases such as diarrhea caused by biological contaminants in water, both public and private water supplies have become increasingly vulnerable to the effects of industrialized activity. Fertilizers used in corporate agriculture bring nitrates and other residues to water, while everyday living increasingly brings pharmaceuticals, soaps, and other personal care product residue into the water that Americans drink from tap, bottles, and springs. Traditional threats to health from arsenic in well water and lead from older tap water pipes are still present and compound the risk that Americans face in drinking water.

Unfortunately, it is almost impossible to identify generalized safe practices for assessing the quality and healthfulness of drinking water for all Americans. The quality of tap water and bottled water is highly dependent on where the water originates, how it is stored, and how it reaches the consumer. The “look” and “smell” of drinking water are often poor indicators of quality. For example, heavy metals (e.g. arsenic, lead) do not make water look cloudy or smell funny, but the health impacts of these heavy metals can be severe, chronic, and even fatal. A few rules of thumb:

• If you receive your water from a public water supply, contact your water company to acquire the latest water quality reports (most public water companies send periodic information to your home). Get to know the contaminants of concern in your area (including where the water originates) and filter your water for those contaminants. If your water source has a history of water quality problems, have your tap water periodically tested for top contaminants. If the public water treatment system uses chlorine (which does make water smell “funny”), consider using a filter that reduces chlorine in your tap water.
• If you are on a private well, test your water according to the soil and use of land above the well. If animals or septic systems are located near the well, test the water regularly for fecal coliform, and specifically e. coli bacteria. If agriculture is nearby, test for pesticides, nitrates, and organic contaminants. If the geology nearby is rocky, test the water for arsenic.
• And, if you have a home or facility built before 1930 or a more recently constructed home that has copper pipes, have the tap water tested regularly for lead which may be present due to lead solder or lead pipes.
• Finally, if your community is impacted by natural disaster, consider broad-scale community testing of water supplies. Particularly during flooding events, water treatment plants can no longer do their jobs properly and any tap water should be regarded as suspicious and potentially harmful. During and after a natural disaster, bottled water is definitely a better bet, until the local water supply can be fully tested and throughly vetted for human use.