Skip links and keyboard navigation

Water risk management plans glossary

Acceptable level of risk

The level of risk a facility is prepared to accept for a hazard and/or hazardous event. Risk levels range from low to very high. A facility should determine its acceptable level of risk for each identified hazard and/or hazardous event before performing a risk assessment.

Approved provider

An entity for which an approval is in force under the Aged Care Act 1997 (Commonwealth).

Backflow prevention device

A device used to prevent reverse flow within a water distribution system which could draw contaminated water back into the system.


A thin, robust layer of microbial growth, adhering to a solid surface (e.g. the inside of a water distribution pipe) comprising bacteria, moulds and other microorganisms.

Boil water alert

A message issued by a water service provider on the basis of a suspected or confirmed contamination by pathogenic microorganisms (e.g. Escherichia coli, Cryptosporidium).

Chemical disinfectants

Antimicrobial agents applied to non-living objects to destroy microorganisms that are living on the objects. Disinfectants target and destroy the cell wall of microbes or interfere with the metabolism, but are not necessarily able to kill all microorganisms, such as resistant bacterial spores.

Control measure

An action/activity undertaken to reduce or prevent a hazard.

Control point

Location within a water distribution facility at which a hazard may be reduced or prevented (e.g. point-of-entry into a facility, water leaving a storage tank within the facility).

Critical limit

Maximum and/or minimum value set for a particular parameter, measured during monitoring (operational and verification) that indicates controls are effective.

Dead leg

Section within a water distribution system that does not allow the flow of water.

Disinfection residual

The level of disinfectant remaining in a water distribution system after the disinfectant has been dosed.

Distal outlets

Those outlets in a water distribution system located furthest from the water source. For a cold water system the source could be the inlet to the facility and for a hot water system the source could be the hot water storage tank.

Dosing point

The location where small quantities of chemical are fed (sometimes at intervals) into a water distribution system.

Drinking water service provider

All councils or businesses involved in treating, storing, distributing and reticulating water for drinking purposes. They must be registered under the Water Supply (Safety and Reliability) Act 2008 to provide the drinking water service, and are subject to state government regulation.

Elastomeric seals

A type of joint seal for pipes


Building(s) sharing plumbing connections under the control of the facility manager, even when not used for clinical purposes.

Flow restrictors

A device designed to limit the flow of water that comes out of a tap or other dispenser.

Free chlorine residual

Concentration of residual chlorine in water that is present as dissolved gas (Cl2), hypochlorous acid (HOCl) and/or hypochlorite ions (ClO-).


An agent (microbiological, chemical or physical) that has the potential to cause harm to patients/residents (e.g. Legionella pneumophila or water above 50°C).

Hazard source

A location or condition that can give rise to, or increase, a hazard (e.g. a dead leg in the plumbing which is a source for stagnant water and hazard proliferation, under suitable conditions).

Hazardous event

A situation that can lead to the presence of hazard or hazardous source (e.g. a decrease in temperature in a hot water system can provide conditions suitable for Legionella growth).

Health risk

The risk of a person being harmed from the water distribution system.

Heterotrophic colony count / Heterotrophic plate count

A method that measures colony formation, on culture media, of heterotrophic bacteria in water. This gives an indication of the total microbial load in a water supply, but does not indicate the safety or otherwise of the water.

Hot water heaters/system

A heated water system that delivers heated water through the majority of a water distribution system at a temperature equal to or greater than 60°C. May include thermostatic mixing valves.

Interruption to supply

Scheduled or unscheduled, temporary break in supply of drinking water to a facility.


Insulation wrapped around pipes to maintain water temperature and prevent heat transfer from hot to cold pipes.


Bacterium which causes Legionnaires’ disease, some species of which thrive in water distribution systems.


An illness caused by exposure to Legionella

Mixer tap

A tap for controlling the flow of water enabling hot and cold water out of the same pipe. It ensures the flow of each is controlled separately so that the temperature of the water coming out can be adjusted.

Operational monitoring

Scheduled, real-time monitoring of specific parameters within a water distribution system to check the effectiveness of control measures (e.g. checking the temperature of the hot water system).

Oxidising agent

Chlorine and oxygen are examples of strong oxidizers. They act by oxidizing the cell membrane of microorganisms, resulting in a loss of structure leading to cell death.

Person in charge

The person who has supervisory responsibility for the day-to-day operation and control of the facility.


In the context of water analysis, a photometer is an instrument for very precisely measuring a range of different chemical properties of water.


Location where water is used e.g. shower head, tap outlet.

Prescribed facility

(a) a public sector hospital that provides treatment or care to inpatients; or
(b) a private health facility licensed under the Private Health Facilities Act 1999; or
(c) a State aged care facility; or
(d) a residential aged care facility, other than a State aged care facility, prescribed by regulation.

Residential aged care facility

A facility at which an approved provider provides residential care under the Aged Care Act 1997 (Commonwealth).

Responsible person

(a) for a prescribed facility that is a public sector hospital—the health service chief executive for the public sector hospital; or
(b) for a prescribed facility that is a private health facility licensed under the Private Health Facilities Act1999—the licensee for the private health facility under that Act; or
(c) for a prescribed facility that is a State aged care facility—the health service chief executive for the State aged care facility; or
(d) for a prescribed facility that is a residential aged care facility, other than a State aged care facility—the approved provider that provides residential care at the residential aged care facility.

Reticulated non-potable

Non-drinking water reticulation system.

Reticulated potable

Network of pipes that only carry drinking water.

Return loop

A plumbing configuration where the hot/warm water pipe continues from one tap to the next in a loop back to the same location (normally the cold water inlet to the hot/warm water system).


The likelihood that a hazard or hazardous event will cause harm to humans in a specific timeframe and the consequences (and magnitude) of the harm.

Scald / scalding

A form of thermal burn resulting from exposure to hot water or steam. Most scalds are considered first or second degree burns, but third degree burns can result, especially with prolonged contact with the heat source.

Sentinel outlet

Locations in the water distribution system selected as being representative of larger sections of the system or where higher risk patients/residents may be exposed to a hazard.

Sluice room

A room where items such as incontinence pads and bed pans are disposed, and reusable products are cleaned and disinfected.

State aged care facility

A residential aged care facility at which the State provides residential care.

Stop valve

A valve used to stop the flow of water within a pipe.

Tapware aerator

Also known as flow regulator. A small attachment that fits either onto the end of the tap or inside of the existing spout. It will control the amount of water that flows through the tap without affecting the water pressure, creating a no-splashing stream and often delivering a mixture of water and air.

Tempering devices

A device that mixes hot and cold water to deliver water at a desired temperature.

Thermostatic mixing valve (TMV)

A valve that automatically blends hot water with cold water to deliver warm water for sanitary purposes to prevent scalding.

Ultra violet (UV) disinfection

Non-chemical disinfection process which kills microorganisms by a physical process.

Unacceptable level of risk

Any level of risk not considered an acceptable level of risk. These risks must have controls applied such that they are no longer unacceptable.

Unused outlet

An outlet that is not used, for example, a basin located in a room converted into an office/store room. This can create a dead leg.

Verification monitoring

Scheduled but not real-time monitoring of specific parameters to verify the effectiveness of the water risk management plan in managing the risks posed by the water within the water distribution system (e.g. testing for Legionella).

Warm water system

A heated water system that distributes warm water at approximately 45°C throughout the majority or all of the water distribution system, for sanitary purposes to prevent scalding.

Water distribution system

Infrastructure within a facility from every point where water enters the facility through the infrastructure to every point where the water is used.

Microorganisms, substances or physical properties of water that are reasonably expected to cause injury or illness to an individual.

Water reticulation system

Any network of pipes used to transport water.

Water risk management plan

Documented, risk based strategy to ensure water-related hazards, such as Legionella are managed to ensure the protection of public health.

Water stagnation

The condition where water ceases to flow and is liable to enhance microbiological growth.

Water storages

Tanks or other storage vessels where water, after entering a facility, may be stored for a period of time, before being used within a facility.

Water treatment

Processes used to make the water more acceptable for its end use e.g. chlorination via a chlorine dosing unit.

Last updated: 29 June 2017