Treated water that's too pure lets arsenic sneak in

http://www.eurekalert.org/pub_releases/2016-01/agi-etw010716.php

Public Release: 7-Jan-2016
EARTH: Treated water that's too pure lets arsenic sneak in
American Geosciences Institute

In an effort to reduce water use in California, communities are turning to wastewater purification. This wastewater is being made so pure that it's actually causing problems: EARTH Magazine reports on a new study that showed that ultra-purified water allowed minute amounts of arsenic to leach from the surrounding bedrock into the water.

The study was conducted on water from the Orange County Water District, which purifies wastewater with a comprehensive process including microfiltration, reverse osmosis and UV light treatments. That purified water is then injected into a local aquifer. Over an approximately six-month residence time, that purified water accumulated trace amounts of arsenic. Geoscientists were called in to help solve the mystery of its occurrence. Learn the source of the arsenic and how the local geology and water chemistry interacted in the latest story from EARTH Magazine: http://bit.ly/1Z2o6v8.