Central air conditioning units typically need to be connected to a drain, because manually removing the volume of condensate water extracted by such systems in containers is impractical. If the condensate water is directed into the sewer system, it should be suitably trapped to prevent septic odors and sewer gases from entering the building. The condensate should not be directed into a septic system of a house, because it doesn’t need to be treated as effluent. When the height of the air handler (containing the evaporator) is above the level of the surface drains used for rain water the condensate drain lines can often be routed into them. Air handlers located below grade level, e.g. the basement of a house, may need to use a condensate pump to lift the water to a surface drain.