Decentralized Wastewater Glossary

component that removes hardness from a water source.

reduction in the number of and/or removal of polyvalent cations which are the principal cause of hardness in water.

upper surface of groundwater or that level in the ground where the water is at atmospheric pressure.

by-product from a water treatment device, such as regeneration water from an ion-exchange unit, reject water from a reverse-osmosis unit, or the backwash from an iron filter.

well constructed for the purpose of extracting potable water at a beneficial rate.

toilet specifically designed to receive non-water-carried human waste; includes chemical, composting, pit, and vault toilets.

drainage basin area contained within the bounds specified by a divide and above a specified point such as a lake, wetland, or stream.

condition ascribed to a device that is constructed so that no water can move into or out of it except by design through inlets and outlets.

soil structure descriptor for soil aggregates with wedge-shaped blocks that are larger at the top and narrow at the bottom.

1. drain hole to allow moisture or air to escape, such as a weep hole in a concrete tank that allows water to drain out of tanks while they are in storage; 2. drain hole in the discharge assembly that allows drainback to the tank after a dosing event.

device designed to measure or control flow; consists of a wall or obstruction of known geometric shape placed perpendicular to the direction of flow.

shaft bored or drilled into the ground for purposes of accessing a saturated zone.

device with perforations that restricts entry of soil particles while facilitating free drainage of liquid into the well.

material of variable size with minimum pore space; also known as poorly-sorted.

material of uniform size with maximum void space; also known as poorly-graded.

soil that contains significantly more moisture than moist soil, but in such a range of values that cohesive material will slump or begin to flow when vibrated; granular material that would exhibit cohesive properties when moist will lose those cohesive properties when wet.

areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions; wetlands generally include swamps, marshes, bogs, and similar areas; constructed wetlands used in wastewater treatment are purposely excluded.

propulsion method using wheels, typically resulting in greater ground pressure due to limited soil contact area; see also tracked.

unsaturated flow on the surface of a media or soil particles which moves liquid from a location of greater moisture content to a location with lesser moisture content.                             

air movement across the liquid surface of a constructed wetland, lagoon or other exposed treatment tank or over a soil treatment area.

trench; conventional trench; distribution media; biomat; biozone

see mound.

isolated waste stream consisting of urine collected from specific fixtures and not contaminated by feces or diluted by graywater sources; see also urine separating device.

portion of a component that is separately managed as a single unit.

see vadose zone.

layers of soil or rock material surrounding the zone of treatment through which the effluent moves away from the final treatment and dispersal component.

layer in the ground in which interstitial voids (cracks, crevices, holes, etc.) are filled with water; the level at the top of this zone is the water table.

see biozone.

valve that mechanically and sequentially diverts the flow of fluid to multiple zones within a soil treatment area.

jelly-like masses of bacteria found in both the trickling filter and activated sludge processes; masses may be formed for or function as the protection against predators and for storage of food supplies.