What is mains surface water drainage?
Edited
Mains surface water drainage means that rainwater from roofs, gutters, and paved areas is carried away into the public sewer system operated by the local water company. If the property is not connected, the water may instead drain into a soakaway, ditch, or watercourse on or near the property. If you are unsure, please contact your conveyancer or a surveyor for assistance.