Public capital-spending projects involving technologies such as water supply, street paving, and sewers were characteristic of American cities during the late nineteenth and early twentieth centuries. All involved questions of technology adoption and design considerations. The decision by a municipality to construct a sewerage or water carriage system of waste removal involved a critical design decision between two forms of sewer technology—the combined sewer and the separate one. In normal use the combined system carries both household wastes and storm water in one large pipe. The separate system theoretically provided two sets of pipe—a small-diameter pipe for household wastes, called a sanitary sewer, and a larger-diameter pipe for 290storm water from streets, roofs, and yards. In many cases, however, cities with separate systems only constructed sanitary sewers and made no provision for underground removal of storm water.