Chromium in Evanston's Water Has Always Been Below Detection Level
The City of Evanston's Water Division has annually tested for total chromium in their drinking water since 1979. However, Underwriter’s Laboratory, the nationally recognized water quality laboratory utilized by Evanston for this type of water analysis, only has equipment capable of measuring the level of total chromium in water to 5.0 parts per billion (ppb). The chromium in Evanston’s water has always been below this detection level and reported as non-detectable, or less than 5.0 ppb.
A December 19, 2010 article in the Chicago Tribune indicated that the hexavalent chromium level in Chicago’s drinking water to be 0.18 ppb. Based on the proximity of Evanston’s water intakes to Chicago’s and similarities in the water treatment processes, the Evanston staff assumes that the level of hexavalent chromium in the Evanston drinking water would be approximately the same as Chicago’s. It should be noted that the EPA only requires that total chromium levels be tested. Total chromium includes hexavalent and other forms of the metal.
The current US Environmental Protection Agency (EPA) and Illinois EPA maximum contaminant (MCL) level for chromium is 100.0 ppb. This standard is established in the National Primary Drinking Water Regulations and all public water supplies must abide by these regulations. MCLs are established to protect human health based on what the EPA believes, given present technology and resources to detect and treat, is the lowest level to which water systems can reasonably be required to remove a contaminant.
At this time, the EPA considers this level of protection adequate to avoid skin irritation or ulceration during short term exposure or damage to liver, kidney circulatory and nerve tissues during long term (life time) exposure.
Per the Tribune article, the Environmental Working Group (EWG) commissioned the testing for hexavalent chromium levels in tap water from 35 cities and then compared these results to a proposed California public health goal of 0.06 ppb. The EWG recommendation is that the EPA should move expeditiously to establish a legal limit for hexavalent chromium in tap water and require water utilities to test for it. The EWG report can be viewed at their website www.ewg.org.
If Evanston were required by the EPA to remove hexavalent chromium to 0.06 ppb, a reverse osmosis / membrane technology treatment process would be required. Based on the capacity of the Evanston water treatment plant, conversion to this technology would cost at a minimum $110 million to install. In addition, this type of treatment process would require an increase in maintenance expenditures of approximately $3 million annually.
Attached to this memorandum are a four page fact sheet and a two page document regarding the Chromium 6 Draft PHG Talking Points provided by the Office of Environmental Health Hazard Assessment (OEHHA), California EPA, the organization that proposed the 0.06 ppb public health goal.
Evanston’s Water Division staff is investigating what laboratories are capable of testing for hexavalent chromium at the levels indicated in the Tribune article. Pending laboratory availability and testing cost, the Water Division proposes to have the level of hexavalent chromium in the Evanston tap water determined and then make this information available to our customers.
As indicated in the talking points here>>>, bottled water is not required to meet any higher standard than tap water and people should not interpret a PHG as a reason to limit their water consumption from a community water system.