Objectionable tastes and odors in public water supplies are primarily due to the presence of?

The presence of objectionable tastes and odors in public water supplies is primarily attributed to algae and protozoa. Algae can produce various organic compounds that can impart unpleasant tastes and odors when they are present in excessive amounts. During blooms, certain types of algae release metabolites like geosmin and 2-Methylisoborneol (MIB), which are known to create earthy and musty smells that can be detected even at very low concentrations.

Protozoa, while less commonly recognized for taste and odor issues compared to algae, can also contribute to these characteristics, especially when they die off or in instances of high biomass. The decomposition of these organisms can lead to the release of compounds that can exacerbate issues with taste and odor.

In comparison, animal remains generally lead to more pronounced health concerns rather than specifically causing taste and odor problems. Dissolved oxygen, while important for aquatic health, is not directly responsible for generating tastes and odors. Yeasts and molds can occasionally impact water quality but are not the primary cause of the objectionable tastes and odors experienced in water supplies, as these are more often associated with food and alcoholic beverages than with potable water.