adobe • Bricks dried slowly in the sun, but not in direct sunlight, made of clay that has been thoroughly mixed with water, often with straw, grass or other natural fibres added.
adsorption • The adhesion, in a thin layer, of liquids to the surface of solids with which they are in contact.
aerobic • Living or taking place in the presence of air or free oxygen.
agency • Government department, or bilateral, international, nongovernmental or similar organization taking primary responsibility for a project.
aggregate • Gravel, broken rock or sand that is mixed with cement to make concrete; coarse aggregate particles are normally 6-18 mm in size; sand is known as fine aggregate.
anaerobic • Living or taking place in the absence of air or free oxygen.
aqua-privy • Latrine in which excreta fall directly through a submerged pipe into a watertight settling chamber below the floor, and from which effluent overflows to a soakaway or drain.
biochemical oxygen demand • See BOD.
biodegradable • Able to be broken down by biological processes through the action of bacteria and other microorganisms.
biogas • Mixture of gases, mostly methane and carbon dioxide, produced in anaerobic decomposition of waste materials.
BOD • Biochemical oxygen demand: the mass of oxygen consumed by organic matter during aerobic decomposition under standard conditions, usually measured in milligrams per litre during five days; a measure of the concentration of sewage.
cement mortar • Mixture of four or fewer parts of sand to one part of cement, with a suitable amount of water.
cesspit • A subsurface container for the retention of sewage until it is removed by vacuum tanker or other means.
compost • Humus produced by composting of organic matter; valued as a fertilizer or soil conditioner.
composting • Controlled decomposition of organic solid waste in moist conditions so as to produce humus.
concrete • Mixture of cement, sand, aggregate and water which hardens to a stone-like solid.
corbelling • Construction in which bricks, blocks or stones are built so that an upper course projects inwards beyond the course below to support a load, such as a manhole cover or squatting slab.
curing • Process of keeping concrete or mortar damp for at least the first week after it is cast so that the cement always has enough water to harden.
decomposition • Breakdown of organic matter into more stable forms by the action of aerobic or anaerobic microorganisms.
desludging • Removing settled solids from pits, vaults, tanks and septic tanks.
digestion • Decomposition of organic matter in wet conditions.
drain • Pipe or channel for carrying wastewater, effluent, rainwater or surface water.
drainage field • Area of land used for infiltration of wastewater into soil.
drainage trench • Trench in which a drain is surrounded by stone or other inert material used as a soakaway for liquid dispersion.
effluent • Liquid flowing out of a tank or sewage works.
excreta • Faeces and urine.
facultative anaerobe • Organism that can live in either the presence or absence of air or free oxygen.
fall • Slope along a pipe or channel or across a floor, measured as the amount by which one point is lower than a higher point.
ferrocement • Cement mortar reinforced by layers of steel mesh.
flotation • Process by which solids less dense than water rise to form a scum.
former (mould) • Frame, usually wooden, to hold and maintain the shape of concrete while it is setting.
greywater • See sullage.
groundwater • Water beneath the ground surface.
helminth • A worm, which may be parasitic or free-living.
host • A man or animal in which a parasite lives and from which it obtains food.
humus • Decomposed vegetable matter - the end-product of the composting process.
invert • Bottom of the inside of a pipe or channel.
larva • Worm-like stage of development of insects and helminths, which can move and seek food.
latrine • Place or building, not normally within a house or other building, for deposition, retention and sometimes decomposition of excreta.
mortar • Mixture of mud, or of lime and/or cement with sand and water, used for joining or for providing a smooth waterproof surface.
mould • See former.
nightsoil • Human excreta, with or without anal cleaning material, which are deposited in a bucket or other receptacle for manual removal (often taking place at night).
offset pit • Pit that is partially or wholly displaced from its superstructure.
overhung latrine • Latrine sited such that excreta falls directly into the sea or other body of water.
pan • Basin to receive excreta which are then flushed into an outlet pipe by water poured in or by water delivered around the rim of the pan from a cistern.
parasite • Organism that lives in or on another living organism, called the host, from which it obtains its food.
pathogen • Organism that causes disease.
percolation • Movement of liquids through soil.
pit latrine • Latrine with a pit for accumulation and decomposition of excreta and from which liquid infiltrates into the surrounding soil.
pollution • The addition of harmful liquid, solid or gaseous substances to water, soil or air.
pour-flush latrine • Latrine where a small quantity of water is poured in to flush excreta through a water seal into a pit.
programme • Continuous undertaking for planned objectives with commitment by an institution for long-term support of operation and maintenance; may include a series of projects.
project • Planned budgeted event with realizable goals within a specified time period.
retention time • Time taken for a volume of liquid to pass through a tank or treatment process, or the time during which a solid or liquid is held in a container.
sanitation • The means of collecting and disposing of excreta and community liquid waste in a hygienic way so as not to endanger the health of individuals or the community as a whole.
screed • Layer of mortar (usually cement mortar) laid to finish a floor surface.
scum • Layer of suspended solids less dense than water and floating on top of liquid waste from which they have separated by flotation.
sedimentation • Process by which suspended solids denser than water settle as sludge.
septic tank • Watertight chamber for the retention, partial treatment, and discharge for further treatment, of sewage.
sewage • Wastewater that usually includes excreta and that is, will be, or has been carried in a sewer.
sewer • Pipe or conduit through which sewage is carried.
sewerage system • System of interconnected sewers.
sludge • Solids that have been separated from liquid waste by sedimentation.
soakaway • Soakpit or drainage trench for subsoil dispersion of liquid waste.
soakpit • Hole dug in the ground serving as a soakaway.
soffit • Top of the inner surface of a pipe (also known as "crown") or lower surface of a slab.
squat hole • Hole in the floor of a latrine through which excreta fall directly to a pit below.
sullage • Wastewater from bathing, laundry, preparation of food, cooking and other personal and domestic activities that does not contain excreta.
superstructure • Screen or building of a latrine above the floor that provides privacy and protection for users.
surface water • Water from rain, storms or other precipitation, or street washing lying on or flowing across the surface of the ground.
toilet • Place for defecation and urination, which may be the superstructure of a latrine.
toilet, chemical • Receptacle used for defecation and urination that contains a strong chemical disinfectant which retards decomposition and reduces smell.
transpiration • Loss of moisture by a plant through its leaves.
trap • See water seal.
vacuum tanker • Lorry-mounted tank into which the contents of septic tanks, aqua-privies, cesspits, vaults or pits are drawn by vacuum pump for transport to a treatment or disposal site.
vault • Watertight tank for storage of excreta.
vector • Insect or other animal that can transmit infection directly or indirectly from one person to another, or from an infected animal to a person.
vent pipe • Pipe provided to facilitate the escape of gases from a latrine or septic tank.
VIP latrine • Ventilated improved pit latrine; pit latrine with a screened vent pipe and a partially dark interior to the superstructure.
wastewater • Sewage or sullage.
water closet (WC) • Pan from which excreta is flushed by water into a drain.
water seal • Water held in a U-shaped pipe or hemispherical bowl connecting a pan to a pipe, channel or pit to prevent the escape of gases and insects from the sewer or pit.
water table • Surface level of groundwater.
Y-junction • Chamber in which liquid may be directed along either of two pipes or channels.