Public Notice – City of Fort Collins Public Water System ID No. CO0135291
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Summary

The City of Fort Collins Utilities (Utilities) received a Tier 3 Monitoring and Sampling Violation from the Colorado Department of Public Health and Environment (CDPHE) for incorrectly testing for free available chlorine (FAC) in the water distribution system. This error did not impact the water treatment process.

The Colorado state Drinking Water Regulation 11 requires that a public water system maintain at least 0.2 mg/L FAC in the distribution system. The Utilities tests for FAC on a weekly basis at 26 sites throughout the treated water distribution system. The incorrect testing reagent was inadvertently ordered and used for the FAC test, producing results for "total chlorine" instead of FAC from February 27 to May 30, 2017. Therefore, the Utilities cannot ensure that a level of 0.2 mg/L of FAC was maintained throughout the distribution system. However, the error in this testing issue did not impact the water treatment process or the treatment facility operations. The water treatment facility monitors water quality as the treated water leaves the facility (entry point). That monitoring, as well as other distribution system monitoring during this time period, confirm that treated water continually met water quality standards.

Citizens and customers do not need to take any actions due to this testing error. Laboratory and testing procedures have been corrected to protect against this type of error from happening in the future.

Background

Chlorine is added to the city's drinking water in the treatment process to eliminate potentially harmful pathogens and must remain at prescribed levels throughout the distribution system. To monitor chlorine levels in the treated water, Utilities conducts approximately 100 tests per month for FAC at locations throughout the distribution system, including city buildings and businesses. At the same time and locations, Utilities also monitors for total coliform and Escherichia coli (E.coli).

Viewed together, these analytical results provide valuable information on the microbial characteristics of the treated water. The FAC value indicates how much chlorine is available to provide protection from microbial growth. The total coliform and E.coli values indicate whether the sample contains these microbes. The Colorado state standard requires treated water to contain at least 0.2 mg/L FAC and the Colorado maximum contaminant level goal for total coliform and E.coli is zero.

When water samples are analyzed for some compounds, such as FAC and total chlorine, chemicals are added to the sample to enable the compound to be measured. For the samples analyzed during the February 27 – May 30, 2017 time period, staff added the incorrect test chemical, thereby unintentionally testing for total chlorine rather than FAC. Total chlorine is different from FAC in that it provides a measure of different types of chlorine and does not specify the actual amount of chlorine available for disinfection.

From February 27 through May 30, 2017, Utilities monitored total coliform and E.coli as required. These results demonstrate that the drinking water was microbiologically safe. See table below for more information.

Corrective Actions

As soon as the error was identified, Utilities began using the correct chemical in the test and also notified the CDPHE and its Colorado Water Quality Control Division of the error.

In further response to the incident, Utilities identified the following measures to put into place to help ensure this type of error does not occur again:

• additional quality checks on the laboratory sample logs,
• an added level of supervisory review to verify that all quality assurance measures are completed,
• a new training process for staff on the standard operating procedures,
• a change to the inventory, ordering and receiving process.

This table summarizes the microbial characteristics of the water during this time period, and indicates that the water met the entry point requirements for residual disinfectant and met the compliance requirements for total coliform sampling.

If you have questions, please contact Jill Oropeza, Water Quality Services Manager, at joropeza@fcgov.com or 970-416-2529.