The state Health Department reinforced its position that Oahu’s drinking water is safe, after new samples showed levels of a toxic chemical known as chromium-6 ranging from 0.32 to 4 parts per billion at 11 pumping stations islandwide.

The Honolulu Board of Water Supply’s screening for hexavalent chromium followed an initial report by the Washington D.C.-based nonprofit Environmental Working Group, which conducted tests of 35 cities, including Honolulu, and found 2 ppb of chromium-6 in a single sample at a residence at Wilhelmina Rise.

The sample was the second-highest level of chromium-6 found among the 35 samples, though it meets U.S. Environmental Protection Agency standards of 100 ppb total chromium.

Health officials said the latest results found chromium-6 throughout the water system, the source of which most likely is from naturally occurring volcanic soils.

The state will test water from all 100 pumping stations islandwide over the next year, as well as neighbor island water stations.