septic tank

Underground system in which sewage is treated and dispersed.

leach field

Land containing perforated pipes through which the water infiltrates the ground.

perforated pipe

Perforated pipe through which water drains in order to filter through the gravel and then into the soil.

distribution box

Device spreading water evenly through the network of drains.

gravel

Bed of small stones absorbing smaller particles found in water to prevent them from blocking the perforated pipes; it also keeps the perforated pipes in place.

tank

Wastewater settles and sewage decomposes naturally in the first compartment. Water then flows into the second compartment.

building sewer

Drainpipe carrying wastewater from the waste stack to the sewage system or septic tank.