Sanitary sewer
（重定向自Foul sewer）
![PVC Sanitary Sewer Installation. Sanitary sewers are sized to carry the amount of sewage generated by the collection area. Sanitary sewers are much smaller than combined sewers designed to also carry surface runoff.](/Images/godic/202501/14/Sansewer4033.jpg")
![Manhole access to sewer; person shows scale](/Images/godic/202501/14/Working_underground4033.jpg")
![Schematic of a conventional sanitary sewer to convey blackwater and greywater from households to a centralized sewage treatment facility[5]](/Images/godic/202501/14/Schematic_of_the_Conventional_Gravity_Sewer4033.jpg")
![A manhole cover for a sanitary sewer access point.](/Images/godic/202501/14/Sewer_cover4033.jpg")
A sanitary sewer or "foul sewer" is an underground carriage system specifically for transporting sewage from houses and commercial buildings through pipes to treatment or disposal. Sanitary sewers are part of an overall system called sewerage or sewage system.