The National Resources Defense Council, a 1.2-million-member group, published a study of the tap water in 19 U.S. cities in 2003 called “What’s On Tap?”

The council graded the 19 cities on three items:

• Is source water protected from pollutants?
• Is the piping system well maintained?
• Are treatment facilities modern and effective?

Various cities did well in some areas but poorly in others. For example,

• Atlanta has poorly maintained piping.
• Albuquerque and San Francisco have poor treatment systems.
• Fresno does not protect its water source.

In general, the study found plenty of worrisome contaminant levels, though little that was technically out of bounds. The problem, said the study authors, was that the quality standards are weak, and systems are antiquated. For example, ” cancer-causing arsenic is currently present in the drinking water of 22 million Americans at average levels of 5 ppb” (parts per billion). That level is well below the EPA’s new standard for arsenic at 10 ppb. Yet it is still dangerous.

Sscientists now know that there is no safe level of arsenic in drinking water,” said the study authors.  And for the plenty of contaminants that are not yet regulated, many municipal water systems allowed contamination higher than the EPA’s “level of concern.”

Overall, the study found excess levels of these contaminants:

• Lead from corroded piping
• Disease-causing organisms
• By-products of chlorine treatment such as trihalomethanes and haloacetic acids. These can cause cancer and reproductive problems.
• Arsenic which causes a variety of problems including cancer.
• Toxic chemicals including radon and the rocket fuel perchlorate.

Study authors expressed concern for infants, pregnant women, and those with compromised immune systems. They also called for comprehensive improvements in the nation’s water supply systems.

If you find all this worrisome, consider getting a home water filter that gives you purer, healthier water.