Clean drinking water is something island residents tend to take for granted, largely because Hawaii has long prided itself on the taste of its tap water, naturally filtered through porous volcanic rock and devoid of the chlorine taste commonly noted in other parts of the country. Even upon closer inspection, we stack up pretty well: The nonprofit Environmental Working Group, based in Washington, D.C., has ranked the Honolulu Board of Water Supply No. 6 nationally for a robust chemical testing program and a relatively low percentage and levels of chemicals detected.

That nonprofit more recently gave the state a bit of a nudge off our complacent roost. Last week EWG issued findings that the cancer-causing chemical known as chromium-6 (also known as hexavalent chromium) turned up in 31 of 35 American cities tested randomly. One trouble spot: Honolulu. A sample taken from an undisclosed location in the Wilhelmina Rise area showed a level of the chemical of 2 parts per billion.

The issue spotlights a failure of federal water-quality oversight where chromium is concerned. Chromium-6 is the chemical made notorious in 1993 in a California case pursued by an environmental activist whose whistleblowing efforts were chronicled in the film named for her, "Erin Brockovich." Since then the Environmental Protection Agency still only requires water utilities to test for total chromium, setting a 100 ppb allowable level for all variants, including the far less toxic, more naturally occurring chromium-3.

Kurt Tsue, the Honolulu water board spokesman, said all of Oahu sites fall well below that ceiling, which is reassuring as far as that goes. The point is, it may not go far enough. California authorities are proposing a much more stringent limit on chromium-6, .06 parts per billion, a level supported by the environmental watchdog group.

To its credit, the water board is going ahead with tests of a random sampling of wells to measure specifically for chromium-6. Other providers of drinking water should do the same statewide. Chromium is found naturally in rocks, plants, soil and volcanic dust, humans and animals, so it’s critical to know how much of this is chromium-6, which is typically produced by industrial processes.

The EPA needs to move quickly to set regulations restricting chromium-6; the whole nation has already waited too long for meaningful guidance. And local water utilities need to release the findings of any tests conducted while waiting on the feds. Meanwhile, Oahu residents can use an online tool (see box) to see the most current test results available for the well serving their location.

It’s been a quarter-century since residents of Central Oahu had to make noise about the way agricultural chemicals contaminated drinking water. It’s time to reawaken that public concern about the unseen, tasteless chemicals that find their way into drinking water and to hold accountable the agencies taxpayers employ to stand guard over its water supply.