Ulsan Waterworks Headquarters Receives "Satisfactory" in This Year's Domestic and International Proficiency Test for Drinking Water

Evaluation of 22 Items Including Hazardous Inorganic Substances
Certified as an Excellent Analysis Institution

The Water Quality Research Institute of the Ulsan Waterworks Headquarters received a "satisfactory" evaluation in all categories in the "2025 Domestic and International Proficiency Test in the Drinking Water Sector," which was conducted to ensure the accuracy and reliability of measurement and analysis data.

As a result, the institute obtained certification as an "Excellent Analysis Institution."

The domestic proficiency test is overseen by the National Institute of Environmental Research, while the international proficiency test is administered by ERA, an environmental testing agency accredited by the International Organization for Standardization (ISO/IEC).

The evaluation covered a total of 22 items, including: 1 item for microorganisms, 9 items for hazardous inorganic substances such as ammonia nitrogen, 6 items for hazardous organic substances such as benzene, 4 items for disinfection by-products such as chloroform, and 2 items for aesthetic impact substances such as chloride ions.

The international proficiency test is classified as "satisfactory," "warning," or "unsatisfactory." A Z-score, which is the standard score representing the deviation between the measured value and the reference value, is considered "satisfactory" if it is 2.0 or less.

A representative of the Water Quality Research Institute stated, "This year’s proficiency test once again recognized our outstanding analytical capabilities as an internationally accredited professional analysis institution," and added, "We will continue to participate in both international and domestic proficiency programs to further enhance our expertise."

Ulsan Waterworks Headquarters.

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