How is non-carbonate hardness (NCH) calculated?

Non-carbonate hardness (NCH) is calculated by taking the total hardness (TH) of water and subtracting the carbonate hardness (CH). Total hardness encompasses all the dissolved minerals contributing to hardness, primarily calcium and magnesium ions, while carbonate hardness specifically accounts for the portion of hardness that can be attributed to the presence of carbonate and bicarbonate ions.

When you subtract carbonate hardness from the total hardness, you effectively isolate the non-carbonate portion, which includes hardness contributed by other ions such as sulfate, chloride, and nitrate as well as any other minerals that do not fall under the category of carbonate hardness. This calculation is crucial in water quality assessment, especially for understanding how different mineral contents affect water treatment processes and aquatic life.

Thus, recognizing the difference between total hardness and carbonate hardness is essential to accurately quantify non-carbonate hardness, and that relationship is captured correctly by the calculation.