It's not rocket science: we want our water free of unhealthy chemicals.

RODALE NEWS, EMMAUS, PA—The U.S. Environmental Protection Agency will not set a drinking-water safety standard for perchlorate, a toxin found in rocket fuel, according to a draft of the EPA proposal obtained by The Washington Post earlier this week. Though the government agency has not made its plans public yet, this suggests tap-water levels of the chemical are likely to go unregulated.

THE DETAILS: While a small amount of perchlorate occurs naturally, higher levels have found their way into our water from chemical plant leaks and as a consequence of storing and testing missiles. The EPA and the Pentagon have been wrangling over safe levels of perchlorate for years, according to a report issued by the Government Accountability Office earlier this year. The Senate Environment & Public Works Committee says a 2005 report showed that 400 sites in 35 states were contaminated with perchlorate—106 of them were in California. The toxin’s been detected in the drinking-water supplies of more than 20 million Americans. In 2006, the EPA revoked a rule requiring some water-system authorities to test for perchlorate levels and report them to the public. It now seems the EPA will not suggest safe levels of perchlorate in drinking water.

WHAT IT MEANS: In the absence of regulation, we’ll have to police our own water supplies. “The new draft proposal is essentially to not regulate drinking-water levels,” says Robert Zoeller, a professor of molecular and cellular neurobiology who studies thyroid function at the University of Massachusetts in Boston. “The health risks to adults are minimal. However, infants, are really in a different category; perchlorate exposure can affect their thyroid hormone levels.” A little investigating will help you figure out if you need to filter what comes out of your tap:

• Check to see if you’re near a contaminated area. See Page 16 of this GAO document for a U.S. map showing contamination levels by state. As of the 2005 report, California, Texas and Nevada rank the worst. Page 33 of the same document shows specific areas where perchlorate concentrations have been found.

• Contact your water supplier and ask them about perchlorate levels. Since the 2006 EPA rule rollback, many are not required to test for perchlorate, but many still do. What’s a safe level? In 2005, the National Academy of Sciences recommended 1 to 6 parts per billion (ppb) as safe, but groups including the Natural Resources Defense Council (NRDC) say that level’s too high and charge that White House and Pentagon officials influenced the report. Ultimately, NRDC would like to see a safe limit of less than 1 ppb set, but they commend states like Massachusetts and California that have since taken the matter in their own hands and recommended safe drinking levels at 2 ppb and 6 ppb, respectively.

• Consider installing a reverse-osmosis filter to keep perchlorate out of your drinking water, especially if you’re pregnant or have a baby or small children in the house. You can find the filters online or at some home-improvement stores. Many are small enough to fit under your sink.

• Complain to the government. Tell your representative and the EPA you have a right to know perchlorate pollution levels, and let them know you want the EPA to set drinking-water safety levels.

• If you’re still worried, you may want to have your own water tested annually by a commercial lab. “I think mostly that municipal water suppliers do a very good job delivering clean water,” Zoeller says. “But I don't think it is a bad idea to have your water tested once a year.”