Hach Classroom Drinking Water Testing Kit
Science History Institute/Conrad Erb

Many people did not appreciate the sophistication of the chemistry in a Hach system. It was quick and easy, and therefore they missed the point.

—Kathryn Hach-Darrow

Today testing your water is as simple as picking up a kit at a local home-improvement store. But the expertise behind these tests—including instrumentation development and knowledge of reagents—is not so simple. So how did these processes and tests become layman-friendly?

The Hach Company was a driving force behind making water-analysis tests that were easy to use. In the 1940s salesmen traveled door to door to sell water softeners to housewives. The fledgling Hach Company saw an opportunity. Clifford and Kathryn Hach, chemists and cofounders of the company, applied their knowledge not only of a chemical called EDTA, a known water softener, but of a dye called Eriochrome Black T. The dye was unstable and required chemical expertise to stabilize it so it could be useful in a test. Together these two compounds provided the basis of the Hach Company’s new water-hardness test, Model 5B Hardness Test Kit, released in 1949. The titration-based test propelled the company to success in the next several decades, and Hach added different parameters to its popular water-analysis kits: laypeople, scientists, and municipal workers alike could use the Hach tests to analyze water.

In an oral history interview Kathryn Hach-Darrow remembered,

The home water-softener business became a big business. This was where we really got our break because we made Cliff’s hardness test into the 5B Test Kit. It was in a little box, and it was cheap. We sold those like crazy. We were in the water-analysis business with that.

Today students are able to use the simple Hach classroom testing kits to understand their local water supply. The tests are a lasting legacy of the simplicity of Hach design and a reminder that simple tests often have complicated chemistry behind them.