Effluent sewer
Effluent sewers also currently serve fewer people than septic systems, which also use septic tanks, but simply dispose of the effluent by draining it into a leach field. About one quarter of United States homes dispose of their wastewater with septic tanks. However, effluent sewers are being looked at as a sewage treatment solution in areas where gravity sewer systems are not well-suited or when the high capital cost to build a gravity system is prohibitive. Areas that are less than ideal for gravity systems include areas that are large, but extremely flat and areas that require long-distance pumping, such as where homes are widely spread out or when several small villages or towns connect their sewage systems so that a centralized plant can be built.
Effluent sewer
Another problem area is a place where there are many homes or businesses at or near the lowest elevation in the area, such as sea level for a coastal city. Typically, waste is pumped uphill under low pressure to the main sewer line in such situations, either after it has been through a septic tank or after it has been ground up into a slurry by a grinder. Grinding can be done when the waste of many homes or businesses is combined or smaller grinders can be installed at each home or business. A disadvantage of using grinders is that they require electricity, and a disadvantage of using septic tanks is that they require solid waste buildup to be removed every one to three years, depending on the size of the tank and the number of people using the system.