Abstract: Aqueous septic tank maintenance compositions, process for their production, methods for their use as well as methods for the maintenance of sewage systems, particularly septic tanks and cesspools are provided. The aqueous septic tank maintenance compositions feature a high proportion of biologically active agents per unit volume or unit weight of the compositions, and reduced numbers of stabilizing compositions generally required to ensure storage and shelf stability of the biologically active agents contained therein. Processes for the production of these aqueous septic tank maintenance compositions, and methods for their use are also disclosed.