Allows water to flow uphill

Small Bore Sewers™ can be installed within rolling terrain and challenging geological conditions, as the SBS™ system can continue flowing over varying gradients, providing solutions to areas with inflective gradients. The small diameter mains provide the designer with a greater degree of flexibility, both vertically and horizontally. Positive elevation differentials can be maintained in the Clearford mains when the overall hydraulic gradient line is negative and appropriate air releases are installed. For stretches of the SBS™ network, liquid wastes can flow uphill within an inflective gradient, slashing excavation requirements and installation costs.

(Modified from source: US EPA web site)