Municipal wastewater contains ∼99.9% water. The remaining constituents include suspended (settleable and nonsettleable) and dissolved solids that have organic and inorganic components, as well as microorganisms. These constituents give physical, chemical, and biological qualities that are characteristics of residential, commercial, and industrial wastewaters.

The objectives of this chapter are to present the physical, chemical, and biological characteristics of municipal wastewater. The material discussed in this chapter include: physical qualities like temperature, color, turbidity, odor and solids, chemical quality, measure of organic matter and strength, priority pollutants, toxicity, and biomonitoring as well as unit waste loading and population equivalent.