The Environmental Working Group has produced a new estimate of the risk of pollutants in public water systems in the US.(1) Their estimate is that roughly 40% of the US population is served by water systems pumping excessive levels of arsenic and other toxins, and this might account for as many as 100,000 cancer cases.
What’s different in this analysis?
This research uses an approach developed by the State of California that looks at the cumulative impact of pollutants, rather than assessing each individual pollutant separately. This is the approach the EPA has applied to air pollution, but not to water pollution. Exposure to these chemicals isn’t one-shot. If they are in you water, you are exposed to them repeatedly over time, and some may collect in your body.
The major pollutants in the US water supply are (1) arsenic and (2) disinfectants/cleaning products. Individually, their nasty; in combination they may be very serious problems.
In the case of arsenic, for example, the California OEHHA defines the level of contaminant that corresponds to a lifetime cancer risk of 1 case in 1 million as 0.004 micrograms per liter (mcg/l).
California has a reputation for applying more rigorous standards to pollution than does the Federal government. That hasn’t kept California from building the largest economy of any state in the US. The State simply provides more protection for its residents than either the Federal government or most other states offer.
What to do: You need to consider water filtration for water used for cooking and drinking in your home and business. The clear message is that you cannot blindly rely on public water systems to do the purification for you. If you have well water, you need to do annual testing at the very least.