Port Washington Water District Staying on Top of Emerging Contaminants

Under the 1996 amendments to the federal Safe Drinking Water Act, the U.S. Environmental Protection Agency is required once every five years to issue a new list of up to 30 unregulated contaminants for which public water systems must monitor. The intent of this rule is to provide baseline occurrence data that the EPA can combine with toxicological research to make decisions about potential future drinking water regulations. The Port Washington Water District completed the third round of this contaminant testing, known as UCMR3, during 2014. Repeat sampling was also conducted during 2016. The 2016 follow-up sampling was voluntary on the part of the District.

The EPA uses the Unregulated Contaminant Monitoring Rule (UCMR) to collect data for contaminants that are suspected to be present in drinking water and do not have health-based standards set under the Safe Drinking Water Act (SDWA) The labs results that are collected through UCMR are used to support EPA’s determination of whether to regulate particular contaminants in the interest of protecting public health.

What do the results mean? The most recent round of testing helped determine whether or not certain contaminants are found in drinking water, at what levels they are found, and in which parts of the country. Depending on how prevalent the contaminants were and at what levels they were found, EPA may conduct further research to determine whether or not to begin regulating some or all of them.

Under the UCMR 3 sampling program chlorate, 1,4-Dioxane, strontium and chromium-6 (Hexavalent Chromium) have been detected in the Port Washington Water District. More detailed information and fact sheets can be obtained on our website at http://www.pwwd.org/news-factsheets.php . As a summary:

• Our chromium test results ranged from below detection limits to 3.90 ppb with an average of 0.80 ppb. These results are lower than the total chromium standard, so there are no special actions our district or customers need to take.
• Chlorate detections ranged from below detection limits to 160 ppb which is far below the World Health Organization 700 ppb guideline, so there are no special actions our district or customers need to take.
• Our 1,4-Dioxane point of entry test results ranged from below detection limits to 1.90 ppb with an average of 0.75 ppb. These results are lower than the New York State Health Department standard for unspecified organic contaminants, so there are no special actions our district or customers need to take.
• Strontium detections ranged from 25 to 306 ppb which is well below the EPA health reference level of 1,500 ppb, so there are no special actions our district or customers need to take.

Will the EPA be setting a standard for chlorate, 1,4-Dioxane and Chromium-6? That is yet to be determined. The EPA regularly reviews drinking water standards as new science becomes available and is currently reviewing new health effects information. Once the review is completed, the EPA will carefully review the conclusions and consider all relevant information to determine whether drinking water standards for chlorate, 1,4-Dioxane and Chromium-6 is needed. The drinking water community is working with the EPA to review all relevant information on the aforementioned contaminants including health effects, occurrence and treatment options. This work will help support the EPA in its decision-making process.