Contracts can specify the recyclable and compostable materials to be collected as well as how they should be collected. Contracts can also allow for additional materials to be added based on specified conditions such as markets for materials or establish a preference or provide incentives for source separation.

Each community needs to define their program based on the myriad of criteria and real-world conditions. Many large communities today believe that a combination of source separation and mixed material processing are critical to achieving zero waste or other diversion goals.

The primary separation in most U.S. programs is of "wet" garbage from "dry" recyclables. Some programs collect containers separated from paper as a "dual stream" instead of as a "single stream" of all recyclables. The diversion rates of single stream and dual stream programs vary greatly.

Some communities have a requirement that residents and/or businesses must keep their materials source separated. The degree of source separation varies.

In addition, many communities are adding another bin for composting grass clippings, tree trimmings and sometimes food scraps.