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.
Sewer gas
Sewer gas is typically restricted from entering buildings through plumbing traps that create a water seal at potential points of entry. In addition, plumbing vents allow sewer gases to be exhausted outdoors. Infrequently used plumbing fixtures may allow sewer gas to enter a home due to evaporation of water in the trap, especially in warm weather. The result is the most common means of sewer gas entering buildings and can be solved easily by using the fixtures regularly or adding water to their drains. One of the most common traps to dry out are floor drains such as those typically placed near home furnaces, water heaters and rooms with underfloor heating. Infrequently used utility sinks, tubs, showers, and restrooms also are common culprits. Trap primers are available that automatically add water to remote or little used traps such as these. Blocked plumbing vents, typically at the roof, also can cause water seals to fail via siphoning of the water.