Sanitary sewer systems carry sewage, gray water, and waste away from buildings, and into wastewater treatment facilities. There are two types of sewer systems, ones that rely on gravity to move water, and force main systems. Gravity sewer systems are the most common because they require the least maintenance, and they are generally cheaper to install. To function properly, the pipe bedding must be graded so that the elevation of the pipe gradually decreases. That allows waste to flow downhill, away from the property, and to the waste treatment facility. Sometimes, the elevations of existing facilities preclude the use of gravity reliant systems. In these cases, a force main may be required. Force mains are systems that rely on pumping equipment to pressurize and move wastewater. These facilities are generally more expensive to install, and more expensive to maintain. They are more expensive because the piping must be durable enough to withstand the pressure created by the pumping equipment. The pumping equipment must also be maintained and monitored to prevent backflow.
