The presence of chlorine in water can be determined using a chlorine test kit. The kit contains a reagent that reacts with chlorine to produce a color change. Depending on the concentration of chlorine in the water, the color of the reagent will change from yellow to orange to red. An orange color indicates that the chlorine concentration is at an acceptable level for most applications, typically between 1 and 3 parts per million (ppm). If the color turns red, it indicates a higher concentration of chlorine, which may require dilution or further treatment to ensure the water is safe for use.