Which term describes sewer systems that combine wastes from different sources?

The correct terminology to describe sewer systems that combine wastes from different sources is "combined sewers." Combined sewers are designed to collect rainwater runoff, domestic sewage, and industrial wastewater within the same pipe system. This approach can be efficient for managing the flow of wastewater and stormwater, especially in older systems where separate sewers for wastewater and stormwater were not initially developed.

In contrast, separate sewers refer to systems where stormwater and sewage are handled by distinct networks, which is intended to prevent potential overflow issues during heavy rainfall or flooding. Dual sewers involve systems that contain two distinct conduits for various types of wastewater, but they do not usually serve the purpose of combining different waste sources as effectively as combined sewers do. Multiple wastewater systems is a more general term that lacks the specificity needed for identifying combined systems.

Thus, "combined sewers" accurately encapsulates the concept of a system that integrates various waste streams into one collection network.