Glossary


At the end of each definition in this Glossary there is a number in brackets. This indicates the number of the Study Session where the term is first used in this OpenWASH module.

Browse the glossary using this index

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A

abstraction

taking water from a source such as groundwater or a river (1)


acoustic logger

device attached to a pipe that can indicate a leak when the noise in the pipe changes (7)


active leakage control

searching for leaks and repairing them (7)


aerated

supplied with air (5)


aerobic

containing oxygen (4)


algal bloom

rapid increase in the population of microscopic algae in water (4)


anaerobic

without oxygen (4)


aquaculture

farming of aquatic (water-living) organisms (1)


aquifers

layers of underground rock that hold water (3)


asset management

systematic process of deploying, operating, maintaining and upgrading assets to ensure continuous water supply at minimal cost (9)


asset register

list of all the fixed assets of an organisation  with information pertaining to the assets (6)


assets

components of a water supply system, such as the treatment plants, process units and all the equipment and facilities (6)


audit trail

documentation of the sequence of activities that led to a given decision (8)


B

back-siphonage

the drawing of external water into a water main as a result of a reduction in pressure in the water main (7)


bacteria

single-celled organisms ranging in size from 0.5 to 5.0 µm (2)


biodegradation

the breaking down of complex substances into simpler substances by micro-organisms (11)


Bishan Gari

a water purifying powder mixture comprising a coagulant/flocculant and a disinfectant, available in Ethiopia (10)


block (water supply)

a given amount of water for which there is a certain water tariff (13)


C

catchment

the total area of surrounding land that slopes towards and drains into a river (4)


ceramic filtration

filtration of water using a ceramic pot (10)


cloth filtration

a means of removing solids from water using fine cotton cloth (10)


coagulant

chemical used in water treatment to neutralise the charge on fine particles (5)


coagulation

neutralisation of the electrical charge of particles by using a coagulant (5)


coarse screens

(in water treatment) steel bars that have a spacing of 5–15 cm (5)


compliance monitoring

analysis of water to check that it is within required standards (8)


concentration

amount of a substance in a given volume of water or air (2)


contact time

length of time for which the water undergoing treatment is exposed to a disinfectant (5)


corrosion

process whereby a metal gets weaker due to a reaction with its environment (7)


criticality

degree of importance (6)


D

defluoridation

removal of excess fluoride from water (5)


diffuse pollution

pollution from non-point sources (4)


diffusion

process by which something moves naturally from a region of high concentration to one of low concentration (11)


disease outbreak

unexpected rise in the number of cases of a disease (14)


disinfection

elimination of micro-organisms that can cause disease (5)


distribution mains

pipes that take water from a service reservoir to other areas for use (1)


drinking water ladder

steps in improvement of quality of water supply (3)


drinking water standards

set of limits for the amounts of specified substances in drinking water (9)


drip-feed irrigation

form of irrigation where water is put at the base of a plant, using narrow pipes (1)


drought

lack of rain that lasts for a long period of time (14)


E

emergencies

sudden, unexpected, hazardous events that call for immediate action (14)


enteric

concerned with the intestine (part of the body where food is digested) (2)


eutrophication

process by which nutrients, especially phosphates and nitrates from agricultural or other activities, build up in a water body causing excessive plant growth and eventual decay, resulting in depletion of oxygen in the water (4)


F

facultative ponds

in a waste stabilisation pond system for wastewater treatment, ponds that have oxygen at the top near the surface and are without oxygen at the bottom of the pond (11)


faecal coliforms

coliform bacteria that originate from faeces (2)


filtration

separation of solids from a liquid using a filter (5)


fine screens

(in water treatment) steel bars with a spacing of 5–20 mm (5)


flash flood

short-duration flooding that occurs due to sudden heavy rainfall that is unable to drain away into the ground (14)


flocculant

chemical that assists the process of flocculation (5)


flocculation

process whereby the size of particles increases as a result of particles combining together (5)


flooding

abnormal rise in water level that can cause damage (14)


fluoridation

addition of fluoride to water (5)


fluorosis

abnormal human condition that results from an excess of fluoride in the body (2)


full cost recovery

where both initial capital costs and operation and maintenance (O&M) costs are all recouped (13)


G

geothermal energy

energy derived from the heat of the Earth (1)


ground penetrating radar

device used to detect water leaks from pipes by identifying where the ground has cavities, or has been disturbed (7)


groundwater

water that is held in underground rocks (1)


H

hazard

anything that can cause harm or damage (8)


hazardous event

an event that can introduce a hazard to a water supply (8)


helminths

worms that live as parasites in humans and other animals (2)


household sand filter

device for purifying water using gravel, coarse sand and fine sand (10)


hydroelectric power

power produced by harnessing the energy of moving water (1)


I

impervious material

material that does not let any liquid pass through it (11)


improved sources (of water)

water sources that are protected from contamination (1)


incident (water supply)

an emergency situation such as a burst pipe (8)


indicator

biological species that gives information about the environment (2)


infectious agents

micro-organisms and viruses that can invade the human body and cause disease (2)


inorganic material

material that does not originate from living organisms (4)


internally displaced people (IDP)

people who have been forced to flee to another part of their own country due to factors beyond their control (14)


L

labour productivity

amount of work that each employee does (15)


leachate

polluting liquid that is produced when water passes through materials and takes with it components from them; usually used to describe the polluted water that seeps out from solid waste disposal sites (4)


leakage

escape of water from pipes or other parts of the water distribution system (7)


life-cycle cost

(of an asset) the sum of one-time, non-recurring costs and recurring costs over the life of the asset (6)


M

maintenance

planned technical activities, or activities carried out in response to a breakdown, to ensure that assets are functioning effectively (6)


maturation ponds

in a waste stabilisation pond system for wastewater treatment,.ponds in which the pathogenic bacteria and viruses in an effluent are eliminated (11)


mechanised

where machines are used to carry out a function (5)


microenterprises

small businesses with fewer than ten people working in them (15)


microfiltration

method for separating particles from water that are 0.05 to 0.5 µm in size (14)


microloan

small amount of money lent at a low interest rate to a person on a low income (13)


micro-organisms

tiny living organisms only visible using a microscope (1)


microstrainer

(in water treatment) rotating drum with a stainless steel fabric with mesh size ranging from 15 µm to 64 µm (5)


Moringa fruit

fruit of the Moringa tree, which grows in tropical countries and can be used as a coagulant for water treatment (10)


N

noise correlator

device that is used at two points on the land surface to pinpoint leaks through the sound that is generated by water escaping (7)


non-degradable plastic

plastic that does not break down over time (12)


non-point source of pollution

source of pollution that encompasses a wide area, the exact point of origin being difficult to ascertain (4)


non-revenue water

water that is supplied by a water utility but from which no income is received (7)


O

operation

routine activities and procedures that are implemented to ensure that the water supply system is working efficiently (6)


operation and maintenance (O&M)

(of a water supply system) all the activities needed to run the system continuously to provide the necessary service (6)


organic matter

material that comes from living organisms (4)


P

palatable water

water that is pleasant to drink (2)


parameter

any measurable factor (9)


pathogenic

disease-causing (1)


percolated

passed through a porous material or through small holes (3)


permeable rocks

rocks that allow water and other liquids to pass through them (3)


photosynthesis

process by which plants convert light energy into chemical energy using carbon dioxide from the air and producing oxygen (4)


phytoplankton

microscopic plants that live in water (12)


point source of pollution

an identifiable source of pollution (4)


pollutants

substances that can cause harm to human health, plants, animals and the environment in general (4)


pollution

introduction into the environment of substances likely to cause harm to humans, animals, plants and the environment in general (4)


potable water

see safe drinking water (2)


pre-chlorination

chlorination before the main treatment stages of the water purification process (5)


precipitation

any form of water that falls on the Earth’s surface (rain, snow, hail) (3)


proactive leakage control

taking action to prevent leaks in water pipes from occurring (7)


protected water sources

water sources that have structures to prevent the entry of contaminants (3)


protozoa

single-celled micro-organisms much larger than bacteria (2)


public–private partnership

collaboration between a public body and a private company (15)


R

rainwater harvesting

process of collecting and storing rainwater (3)


raw water

water that has not yet been treated (1)


representative sample

sample that has all the characteristics of the matter that it was taken from (12)


residual chlorine

(in water treatment) the amount of chlorine left in water after all the pollutants have reacted with it (5)


resilience

ability to withstand shock, stress or a natural hazard (5)


retention time

(in wastewater treatment) the time that effluent spends in a given environment, e.g. in a sedimentation tank or a stabilisation pond (11)


risk

the chance of a hazard occurring (8)


risk assessment

process by which the likelihood of harm from a potential hazard is assessed (8)


run-off

rainwater that ‘runs off’ the land i.e. flows over the land surface (3)


S

safe drinking water

water that does not have any components that can harm people (2)


sand dam

method of storing water using sand held behind a small dam (3)


sanitary inspection

process for identifying pollution sources and health hazards around a water source (12)


sanitation

prevention of human contact with waste, particularly human waste (2)


sedimentation

settling of solids in a water body (5)


sediments

solids that have settled at the bottom of a river or other water body (4)


septic tank

underground tank into which sewage is piped (4)


service reservoirs

stores of water that balance the fluctuating water demands of users against the steady output of a water treatment plant (1)


sewage

mixed wastewater that contains human waste from flush toilets (4)


sewerage

network of sewers i.e. underground pipes for carrying sewage (4)


smart meter

meter that electronically registers the volume of water used and may send water consumption data electronically to the water utility (13)


social tariff

water tariff for those who are poor, which aims to recover only operation and maintenance costs (13)


soil erosion

washing away of soil by rainwater run-off (4)


solar disinfection (SODIS)

disinfection of water using the ultraviolet radiation and heat of the sun (10)


spray irrigation

form of irrigation where water is sprayed over plants (1)


spring

place where water flows out of the ground (1)


stakeholders

individuals, organisations or groups who have an interest in something;

(of a water supply system) representatives of people who would be affected by the water utility’s actions (6)


standardisation

keeping everything the same (6)


standard operating procedures (SOPs)

set of established procedures to be followed in carrying out routine operations (6)


supporting programmes

training programmes that contribute to the delivery of safe water (8)


surface water

water from rivers, lakes, pools and ponds (1)


suspended solids

particles of solid material carried in flowing water (4)


sustainable

able to be maintained at its best for many years (5)


symbiotic relationship

relationship where two parties live together for mutual benefit (11)


T

three-pot method

method for treating water by sedimentation and decanting, using three pots (10)


total coliforms

total number of coliform bacteria (which come from faecal matter and other sources) (2)


transmission mains

pipes that take treated water from a treatment plant to service reservoirs (1)


turbidity

cloudiness caused by a large number of tiny particles in a liquid (2)


U

unprotected water sources

water sources that do not have protective structures to stop them being contaminated (3)


V

viruses

very small infectious particles that are not capacble of independent existence and therefore not classed as organisms (2)


vulnerable (people)

groups of people who are more likely to be harmed by lack of access to safe water through not being able to buy the water they need (13)


W

waste stabilisation ponds

system of ponds to treat wastewater using sunlight and wind (11)


water-based diseases

diseases caused by parasites that spend part of their lifecycle in water (2)


waterborne diseases

diseases caused through the ingestion of water contaminated by human or animal faeces containing pathogens (2)


water emergency

event that disrupts the normal supply of water (14)


water-related diseases

diseases transmitted by insects that breed or feed in or near water (2)


Water Safety Plan

plan that proactively seeks to identify and control risks to safe and continuous water supply (8)


water table

top level of groundwater below the land surface (3)


water tariff

price that is set for water (13)


water tower

elevated structure that has a water tank to supply drinking water by gravity (1)


water treatment

process by which harmful substances are removed from water so that it is safe for human consumption (5)


water utility

organisation that is responsible for producing and distributing drinking water (5)


water-washed diseases

diseases that occur due to inadequate quantity of water being available for good personal hygiene (2)


Wuha Agar

chlorine-based disinfectant for water treatment available in Ethiopia (10)



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