One Source is a manufacturer's representative firm who professionally represents leading manufacturers in the plumbing industry. We strive to provide the most effective service to the wholesale distributor, plumbing contractor, specifying architect/engineer, home builder and facility owner.

Our service area includes northern Illinois and northwest Indiana, including the counties of Boone, Bureau, Cook, DeKalb, DuPage, Grundy, Jo Daviess, Kane, Kendall, Lake, Lee Marshall, McHenry, Ogle, Putnam, Stark, Stephenson, Will, and Winnebago in Illinois, and Lake and Porter counties in Indiana.