What additional test should be conducted at the same time and location as a bacteria sample?

When collecting bacteria samples, conducting a chlorine residual test simultaneously is important because chlorine is a common disinfectant used in water treatment. The presence of chlorine can significantly affect the viability of bacteria in the sample. If chlorine levels are too high, it can kill the bacteria, leading to false results that may indicate a lower bacterial count than actually present in the water.

Additionally, understanding chlorine residual levels provides valuable insight into the overall disinfection process and helps assess whether the water is safe for consumption. By monitoring both the bacterial presence and chlorine residual at the same time, water quality professionals can get a clearer picture of water safety and disinfection effectiveness.

Other tests, like pH, hardness, and fluoride, while also important for understanding water quality, do not have the same direct relationship with bacterial survival and viability as chlorine residual. Therefore, conducting the chlorine residual test alongside bacteria sampling is the most relevant choice.