Sanitary sewer installation with PVC pipe. Sanitary sewers are sized to carry the amount of sewage generated by the collection area. These sewers are much smaller than combined sewers, which are designed to also carry surface runoff.. A sanitary sewer is an underground pipe or tunnel system for transporting sewage from houses and commercial buildings (but not stormwater) to a sewage treatment ... More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.