Objectionable tastes and odors in public water supplies are mostly due to which factor?

The presence of objectionable tastes and odors in public water supplies is primarily associated with algae and protozoa. These organisms can release compounds during their growth and decay that lead to unpleasant sensory characteristics in the water. For instance, certain types of algae produce geosmin and methyl isoborneol, which are earthy and musty tastes and odors that can be quite perceptible, even at low concentrations. This microbial activity often occurs in warm, nutrient-rich waters, causing blooms that can significantly alter the quality of the water.

In contrast, other factors such as dissolved oxygen are essential for maintaining aquatic life and do not themselves contribute directly to off-tastes or odors. Animal remains could potentially introduce pathogens or other issues, but they are less frequently associated with the day-to-day concerns of taste and odor in water supplies. Similarly, yeasts and molds can contribute to flavor profiles in certain contexts but are not the primary culprits when it comes to the generalized unpleasant tastes and odors often encountered in municipal water systems. Therefore, the primary driver of taste and odor issues in water supplies is linked to the activity of algae and protozoa.