Glossary

Actinomycetes:	a group of bacteria that is known to produce geosmin and methylisoborneol (MIB).
acute reference dose (ARfD):	an estimate of the amount a substance in food or drinking water, normally expressed on a body-weight basis, that can be ingested in a period of 24 hours or less without appreciable health risks to the consumer, on the basis of all known facts at the time of the evaluation.
ADWG:	Australian Drinking Water Guidelines (the Guidelines), published by the National Health and Medical Research Council (NHMRC).
aquiclude:	geological material through which no flow of water underground occurs.
aquitard:	aquitards separate aquifers and partially disconnect the flow of water underground.
barrier:	a protective measure against water quality hazards.
biofilm:	microbial populations that may include captured suspended particles that grow on the inside of pipes and other surfaces.
biosolids:	biosolids are treated solids that are collected from wastewater treatment processes.
benchmark dose (BMD):	an exposure due to a dose of a substance associated with a specified low incidence of risk, generally in the range of 1% to 10%, of a health effect; or the dose associated with a specified measure or change of a biological effect.
Campylobacter:	a group of bacteria that is a major cause of diarrhoeal illness.
catchment:	area of land that collects rainfall and contributes to surface water (streams, rivers, wetlands) or to groundwater.
chlorination:	use of chlorine as a means of disinfection.
chloramination:	use of chloramines (compounds formed by the reaction of hypochlorous acid or aqueous chlorine with ammonia) as a means of disinfection.
chlorine demand:	the difference between the amount of chlorine added to water and the amount of residual chlorine.
coagulation:	clumping together of very fine particles into larger particles using chemicals (coagulants) that neutralise the electrical charges of the fine particles and destabilise the particles.
Codex Alimentarius:	a food quality and safety code developed by the Codex Alimentarius Commission of the Food and Agriculture Organization of the United Nations and the World Health Organization.
coliform bacteria:	group of bacteria whose presence in drinking water can be used as an indicator for operational monitoring.
consumer:	an individual or organisation that uses drinking water.
corrective action:	procedures to be followed when monitoring results indicate a deviation occurs from acceptable criteria (adapted from Codex Alimentarius).
critical control point:	a point, step or procedure at which control can be applied and which is essential to prevent or eliminate a hazard or reduce it to an acceptable level (adapted from Codex Alimentarius).
critical limit:	a prescribed tolerance that must be met to ensure that a critical control point effectively controls a potential health hazard; a criterion that separates acceptability from unacceptability (adapted from Codex Alimentarius).
Cryptosporidium:	a microscopic parasite that causes diarrheal disease (cryptosporidiosis), stomach cramps, nausea, vomiting and other gastrointestinal illness. People with severely weakened immune systems (i.e. severely immunocompromised people) are likely to have more severe and more persistent symptoms than healthy individuals (adapted from United States Environmental Protection Agency).
C.t:	the product of residual disinfectant concentration (C) in milligrams per litre determined before or at taps providing water for human consumption, and the corresponding disinfectant contact time (t) in minutes.
cyanobacteria:	bacteria containing chlorophyll and phycobilins, commonly known as ‘blue-green algae’.
Disability Adjusted Life Years (DALYs) per person per year (pppy):	Disability Adjusted Life Years (DALYs) are a measure of population health expressed as burden of disease DALYs are the sum of the years of life lost to due to premature mortality (YLLs) and the years lived with a disability (YLDs) due the disease in a population. DALY per person per year (PPPY) provide an annualised probability of risk of illness.
destratification:	agitation of water body to break up and mix otherwise stable layers of water.
disinfectant:	an oxidising agent (e.g. chlorine, chlorine dioxide, chloramines and ozone) that is added to water in any part of the treatment or distribution process and is intended to kill or inactivate pathogenic (disease-causing) microorganisms.
disinfectant residual:	the amount of free and/or available disinfectant remaining after a given contact time under specified conditions.
disinfection:	the process designed to kill most microorganisms in water, including essentially all pathogenic (disease-causing) bacteria. There are several ways to disinfect, with chlorine being most frequently used in water treatment.
disinfection byproduct:	products of reactions between disinfectants, particularly chlorine, and naturally occurring organic material.
distribution system:	a network of pipes leading from a treatment plant to customers’ plumbing systems.
dose–response:	the quantitative relationship between the dose of an agent and an effect caused by the agent.
dose-response assessment:	the determination of the relationship between the magnitude of dose to an agent and an effect caused by the agent.
drinking water:	water intended primarily for human consumption (but excluding bottled water, for the purposes of these guidelines).
drinking water quality management audit:	the systematic and documented evaluation of activities and processes to confirm that objectives are being met, and which includes an assessment of management system implementation and capability.
drinking water quality monitoring:	the wide-ranging assessment of the quality of water in the distribution system and as supplied to the consumer, which includes the regular sampling and testing performed for assessing conformance with guideline values and compliance with regulatory requirements and agreed levels of service.
drinking water supplier:	an organisation, agency or company that has responsibility and authority for treating and/or supplying drinking water.
drinking water supply system (water supply system):	all aspects from the point of collection of water to the consumer (can include catchments, groundwater systems, source waters, storage reservoirs and intakes, treatment systems, service reservoirs and distribution systems, and consumers).
enteric pathogen:	pathogen found in the gut.
enumeration:	a calculation of the number of individual viable microorganisms in a (water) sample.
epidemiology:	the study of the distribution and determinants of health/disease states in human populations.
Escherichia coli:	bacterium found in the gut, used as an indicator of faecal contamination of water.
eucaryote:	organism with a defined nucleus (animals, plants and fungi, but not bacteria or cyanobacteria).
eutrophication:	degradation of water quality due to enrichment by nutrients such as nitrogen and phosphorus, resulting in excessive algal growth and decay and often low dissolved oxygen in the water.
exposure:	contact of a chemical, physical or biological agent with the outer boundary of an organism (e.g. through inhalation, ingestion or dermal contact).
exposure assessment:	the estimation (qualitative or quantitative) of the magnitude, frequency, duration, route and extent of exposure to one or more contaminated media.
faecal indicator bacteria:	bacteria used to detect and estimate the level of faecal contamination.
filtration:	process in which particulate matter in water is removed by passage through porous media.
flocculation:	process in which small particles are agglomerated into larger particles (which can settle more easily) through gentle stirring by hydraulic or mechanical means.
Giardia lamblia:	a microscopic parasite that causes diarrheal disease (giardiasis), stomach cramps, nausea, vomiting and other gastrointestinal illness.
grab sample:	single sample collected at a particular time and place that represents the composition of the water only at that time and place.
groundwater:	water contained in rocks or subsoil.
guideline value:	the concentration or measure of a water quality characteristic that, based on present knowledge, either does not result in any significant risk to the health of the consumer (health-based guideline value), or is associated with good quality water (aesthetic guideline value).
hazard:	a biological, chemical, physical or radiological agent that has the potential to cause harm.
hazard analysis critical control point (HACCP) system:	a systematic methodology to control safety hazards in a process by applying a two-part technique: first, an analysis that identifies hazards and their severity and likelihood of occurrence; and second, identification of critical control points and their monitoring criteria to establish controls that will reduce, prevent, or eliminate the identified hazards.
hazard control:	the application or implementation of preventive measures that can be used to control identified hazards.
hazard identification:	the process of recognising that a hazard exists and defining its characteristics (AS/NZS 3931:1998).
hazardous event:	an incident or situation that can lead to the presence of a hazard (what can happen and how).
health-based targets:	measurable health, water quality, or performance objectives that are established based on a judgement of safety and on risk assessments of waterborne hazards (adapted from World Health Organization (WHO 2010)).
helminth:	a worm-like invertebrate of the order Helminthes.
heterotrophic:	requiring organic matter synthesised by other organisms for energy and growth.
heterotrophic plate count (HPC):	the number of colonies of heterotrophic bacteria grown on selected solid media at a given temperature and incubation period, usually expressed in number of bacteria per millilitre of sample.
infectivity:	ability to establish infection in a host.
integrated catchment management:	the coordinated planning, use and management of water, land, vegetation and other natural resources on a river or groundwater catchment, based on cooperation between community groups and government agencies to consider all aspects of catchment management.
ISO 9001:2000 (Quality Management):	an international accredited standard that provides a generic framework for quality management systems. Designed to assure conformance to specified requirements by a supplier at all stages during the design, development, production, installation, and servicing of a product, it sets out the requirements needed to achieve an organisation’s aims with respect to guaranteeing a consistent end product.
ISO 14001:1996 (Environmental Management Systems):	an international accredited standard that provides a generic framework for guidance on the development and implementation of an environmental management system to minimise the impacts of business operations on the environment and to foster environmental sustainability.
indicator:	a specific contaminant, group of contaminants or constituent that signals the presence of something else (e.g. Escherichia coli indicate the presence of pathogenic bacteria).
indicator organisms:	microorganisms whose presence is indicative of pollution or of more harmful microorganisms.
jar test:	a laboratory procedure used to estimate the minimum or ideal coagulant dose required to achieve certain water quality goals. A jar test simulates a water treatment plant’s coagulation and flocculation units with differing chemical doses, and mixing and settling times.
limit of detection (LOD):	is normally used to indicate the lowest level that can be reliably detected.
limit of quantitation (LOQ):	the minimum concentration of a substance that can be accurately quantified within a specified degree of confidence; often somewhat higher than the limit of detection.
limit of reporting (LOR):	the minimum concentration of a chemical used for reporting purposes. Results of analyses lower than the LOR are considered to be of lesser reliability and thus may be omitted from reported data.
log removal:	used in reference to the physical–chemical treatment of water to remove, kill, or inactivate microorganisms such as bacteria, protozoa and viruses (1-log removal = 90 per cent reduction in density of the target organism, 2-log removal = 99 per cent reduction, 3-log removal = 99.9 per cent reduction, etc).
log₁₀ reduction value (LRV):	target log₁₀ reduction values (LRVs) are the estimates of pathogen removal/inactivation required to achieve the health-based target of 1 x 10⁻⁶ DALY pppy. LRVs are also used to measure pathogen removal/inactivation attributable to common treatment barriers.
lowest-observed-adverse-effect level (LOAEL):	the lowest exposure level of a chemical substance that causes statistically and biologically significant adverse differences in test samples as compared to other samples not subjected to the chemical substance.
lowest-observed-effect level (LOEL):	the lowest exposure level of a chemical substance that causes statistically and biologically significant differences (adverse or otherwise) in test samples as compared to other samples not subjected to the chemical substance.
maximum risk:	risk in the absence of preventive measures.
microbial band allocation:	the microbial band allocation process is used to categorise the overall level of faecal contamination of the source water using the microbial faecal indicator organism E. coli.
microorganism:	organism too small to be visible to the naked eye. Bacteria, viruses, protozoa, and some fungi and algae are microorganisms.
microbial indicators:	microorganisms such as bacteria and viruses, with certain characteristics (e.g. not pathogenic, have no or minimal growth in water and be reliably detectable in water), which are used either as a surrogate of pathogen behaviour (e.g. log-reduction estimation) in a system or to index the concentration of pathogens in a water body.
multiple barriers:	use of more than one preventive measure as a barrier against hazards.
Naegleria fowleri:	an amoeba that causes a form of meningitis.
nephelometric turbidity unit (NTU):	a measure of turbidity.
no-observed-adverse-effect level (NOAEL):	an exposure level at which there are no statistically or biologically significant increases in the frequency or severity of adverse effects between the exposed and control populations.
no-observed-effect level (NOEL):	an exposure level at which there are no statistically or biological significant differences in the frequency or severity of any effect (adverse or otherwise) between in the exposed and control populations.
oligotrophic:	describes water that contains very low levels of nutrients.
oocyst:	a hardy, thick-walled stage of the life cycle of particular microorganisms (the stage that is shed in the faeces of people infected with parasites such as Cryptosporidium).
operational monitoring:	the planned sequence of measurements and observations used to assess and confirm that individual barriers and preventive strategies for controlling hazards are functioning properly and effectively.
opportunistic pathogens:	microorganisms that generally do not cause disease in most people but can opportunistically cause disease to people with heightened vulnerability (e.g. due to immunosuppression).
particle count:	the results of a microscopic examination of treated water with a ‘particle counter’ — an instrument that classifies suspended particles by number and size.
pathogen:	a disease-causing organism.
pH:	an expression of the intensity of the basic or acid condition of a liquid. Natural waters usually have a pH between 6.5 and 8.5.
point-of-use treatment device:	a treatment device applied to a single tap used for the purpose of reducing contaminants in drinking water at that one tap.
preventive measure:	any planned action, activity or process that is used to prevent hazards from occurring or reduce them to acceptable levels.
procaryote:	organism whose nucleus is not clearly defined (bacteria and cyanobacteria but not animals, plants or fungi).
Protozoa:	a phylum of single-celled animals.
quality:	the totality of characteristics of an entity that bear on its ability to satisfy stated and implied needs; the term ‘quality’ should not be used to express a degree of excellence (AS/NZS ISO 8402:1994).
quality assurance:	all the planned and systematic activities implemented within the quality system, and demonstrated as needed, to provide adequate confidence that an entity will fulfil requirements for quality (AS/NZS ISO 8402:1994).
quality control:	operational techniques and activities that are used to fulfil requirements for quality (AS/NZS ISO 8402:1994).
quality management:	includes both quality control and quality assurance, as well as additional concepts of quality policy, quality planning and quality improvement. Quality management operates throughout the quality system (AS/NZS ISO 8402:1994).
quality system:	organisational structure, procedures, processes and resources needed to implement quality management (AS/NZS ISO 8402:1994).
Quantitative Microbial Risk Assessment (QMRA):	A formal, quantitative risk assessment approach that combines scientific knowledge about the presence and nature of pathogens, their potential fate and transport in the water cycle, the routes of exposure of humans and the health effects that may result from this exposure, as well as the effect of natural and engineered barriers and hygiene measures (WHO 2016: Quantitative Microbial Risk Assessment: Application for Water Safety Management).
radionuclide:	an isotope of an element that is unstable and undergoes radioactive decay.
raw water:	water in its natural state, prior to any treatment; or the water entering the first treatment process of a water treatment plant.
reference pathogen:	groups of pathogens, taking into account variations in characteristics, behaviours and susceptibilities of each group to different treatment processes.
representative sample:	a portion of material or water that is as nearly identical in content and consistency as possible to that in the larger body of material or water being sampled.
reservoir:	any natural or artificial holding area used to store, regulate or control water.
reservoir short circuiting:	occurs when water flows along a nearly direct pathway from the source to the offtake, often resulting in shorter detention times than calculated or presumed.
residual risk:	the risk remaining after consideration of existing preventive measures.
risk:	the likelihood of a hazard causing harm in exposed populations in a specified time frame, including the magnitude of that harm.
risk assessment:	the overall process of using available information to predict how often hazards or specified events may occur (likelihood) and the magnitude of their consequences (adapted from AS/NZS 4360:1999).
risk management:	the systematic evaluation of the water supply system, the identification of hazards and hazardous events, the assessment of risks, and the development and implementation of preventive strategies to manage the risks.
sanitary survey:	a review of the water sources, facilities, equipment, operation and maintenance of a public water system to evaluate its adequacy for producing and distributing safe drinking water.
selective abstraction (selective withdrawal):	taking of source water at a selected time (e.g. stop abstraction when turbidity is high) or location (e.g. reservoir offtake level) based on the quality of the water.
service reservoir/tank:	a storage for drinking water, generally within the distribution system, used to meet fluctuating demands, accommodate emergency requirements and/or equalise operating pressures.
source water:	water in its natural state, before any treatment to make it suitable for drinking.
source water category:	categorisation of source water for determining the treatment target as a log reduction value in the application of microbial health-based targets.
storage reservoir:	a natural or artificial impoundment used to hold water before its treatment and/or distribution.
stratification:	the formation of separate layers (of temperature, plant or animal life) in a lake or reservoir. Each layer has similar characteristics (e.g. all water in the layer has the same temperature).
surface water:	all water naturally open to the atmosphere (e.g. rivers, streams, lakes and reservoirs).
surrogate:	see indicator.
symbiont:	an organism that lives in a mutually beneficial close association with another organism.
target criteria:	quantitative or qualitative parameters established for preventive measures to indicate performance; performance goals.
thermotolerant coliforms:	see coliform bacteria.
total coliforms:	see coliform bacteria.
total quality management:	adds to the concepts of quality management a long-term global management strategy and the participation of all members of the organisation for the benefit of the organisation itself, its members, its customers and society as a whole (AS/NZS ISO 8402:1994).
toxicology:	study of poisons, their effects, antidotes and detection.
treatment train:	a sequence of water treatments (barriers) designed to meet the requirements of a particular environment.
turbidity:	the cloudiness of water caused by the presence of fine suspended matter.
UV transmissivity (UVT):	the measure of the fraction of incident Ultraviolet light (UV) transmitted through a material (e.g. water), usually expressed as a percentage.
validation of processes:	the substantiation by scientific evidence (investigative or experimental studies) of existing or new processes and the operational criteria to ensure capability to effectively control hazards.
verification of drinking water quality:	an assessment of the overall performance of the water supply system and the ultimate quality of drinking water being supplied to consumers; incorporates both drinking water quality monitoring and monitoring of consumer satisfaction.
virus:	molecules of nucleic acid (RNA or DNA) that can enter cells and replicate in them.
vulnerability classification:	Classification of vulnerability to microbial contamination based on evaluation of sources of microbial risk and identification of protective measures (barriers) that may reduce the risk of microbial contamination of a water catchment.
zoonotic:	able to spread from animals to humans