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Storm Water Gravity Main is a conduit utilizing the energy resulting from a difference in elevation to remove unwanted water. The term sewerimplies removal of sewageor surface runoffrather than water intended for use;[1]and the term gravityexcludes water movement induced through force mainsor vacuum sewers. Most sewers are gravity sewers; because gravity offers reliable water movement with no energy costs wherever grades are favorable. Gravity sewers may drain to sumpswhere pumping is required to either force sewage to a distant location or lift sewage to a higher elevation for entry into another gravity sewer, and lift stationsare often required to lift sewage into sewage treatment plants. |