Which test confirms the presence of chlorine or bromine in water?

The DPD test, or N,N-Diethyl-p-phenylenediamine test, is specifically designed to measure the concentration of chlorine and bromine in water. This colorimetric method involves adding a reagent that reacts with free and total chlorine or bromine, resulting in a color change that can be quantitatively measured. This makes it an effective and widely used test in water quality assessments, especially for disinfection effectiveness in drinking water and swimming pools.

In contrast, the coliform bacteria test is used to assess the microbial quality of water and does not measure chemical disinfectants. The hard water test focuses on determining the concentration of calcium and magnesium ions, which are responsible for water hardness, and the pH test measures the acidity or alkalinity of water, not its disinfectant levels. Hence, the DPD test is the only option that directly confirms the presence of chlorine or bromine.