Dozens of U.S. troops in Iraq fell sick at bases using "unmonitored and potentially unsafe" water supplied by the military and a contractor once owned by Vice President Dick Cheney's former company, the Pentagon's internal watchdog says.

A report obtained by The Associated Press said soldiers experienced skin abscesses, cellulitis, skin infections, diarrhea and other illnesses after using discolored, smelly water for personal hygiene and laundry at five U.S. military sites in Iraq.

The Defense Department's inspector general's report, which could be released as early as Monday, found water quality problems between March 2004 and February 2006 at three sites run by contractor KBR Inc., and between January 2004 and December 2006 at two military-operated locations.

It was impossible to link the dirty water definitively to all the illnesses, according to the report. But it said KBR's water quality "was not maintained in accordance with field water sanitary standards" and the military-run sites "were not performing all required quality control tests."

The report said KBR took corrective steps and was providing adequate water quality by November 2006. But military units at the two sites they controlled were still failing to perform required quality control tests and maintain appropriate records by that time.

"Therefore, water suppliers exposed U.S. forces to unmonitored and potentially unsafe water," at the military sites by late 2006, the report said.

The problems did not extend to troops' drinking water, but rather to water used for washing, bathing, shaving and cleaning. Water used for hygiene and laundry must meet minimum safety standards under military regulations because of the potential for harmful exposure through the eyes, nose, mouth, cuts and wounds.

To be sure, the concentrations of these pharmaceuticals are tiny, measured in quantities of parts per billion or trillion, far below the levels of a medical dose. Also, utilities insist their water is safe.

But the presence of so many prescription drugs — and over-the-counter medicines like acetaminophen and ibuprofen — in so much of our drinking water is heightening worries among scientists of long-term consequences to human health.

In the course of a five-month inquiry, the AP discovered that drugs have been detected in the drinking water supplies of 24 major metropolitan areas — from Southern California to Northern New Jersey, from Detroit to Louisville, Ky.

Water providers rarely disclose results of pharmaceutical screenings, unless pressed, the AP found. For example, the head of a group representing major California suppliers said the public "doesn't know how to interpret the information" and might be unduly alarmed.

How do the drugs get into the water?