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Remedial flushing for an operational exceedance

Remedial flushing, in response to a trigger determined by the WRMP, ensures the immediate removal of ‘out of spec’ water through either the entire facility or a localised area of the water distribution system. This allows any chemical disinfectant to enter the localised area, while reducing microbial load and biofilm development.

For the response to the detection of any Legionella bacteria, see remedial flushing for Legionella detection.

When to undertake remedial flushing

Remedial flushing will be implemented on an unscheduled basis, as a corrective action and is recommended to occur as soon as possible after a trigger level is reached. This trigger should be specified in the WRMP and could include an exceedance of a critical limit for an operational control or other operational or maintenance failure.

Operational exceedances, events or situations that could trigger remedial flushing should be noted in your water risk management plan (WRMP) and should include but not be limited to:

  • water temperature or disinfectant residual levels outside a set critical limit or range
  • the presence of discoloured or odorous water
  • following any plumbing maintenance involving alterations, repairs or disturbance of the water distribution system
  • immediately following resolution of a boil water alert or interruption to supply event. There is no point flushing until the event is resolved and clean water is being supplied from the town water supply
  • any other disruptions that cause changes in water quality (for example, natural disaster).

Where to undertake remedial flushing

Depending on the type and location of the operational exceedance, remedial flushing may be required for an entire facility or only a limited number of outlets in a localised area (e.g. single wing, ward or cluster of rooms).

Who should undertake remedial flushing

Remedial flushing should be undertaken by trained and competent staff. A workplace health and safety officer should be consulted before carrying out remedial flushing as personal protective equipment (PPE) may be required (e.g. for scald protection).


Main steps for remedial flushing should meet the following criteria:

  • In the affected area, tapware aerators and flow restrictors (if fitted) should be removed (to ensure there is enough flow through taps). These fittings should be physically and if necessary chemically cleaned (to remove rust and lime scale deposits) and disinfected before reinstallation.
  • In the affected area, shower heads should be removed (if possible), cleaned and then disinfected. This may not be practical for fixed shower heads, but is advisable for flexible hoses. Where a point of use filter is installed as part of the shower head, this should be removed before flushing commences. Replacement of a point of use filter will depend on the nature of the contamination event (e.g. a water main break could send dirty water into the facility thereby reducing the life cycle of the filter. In this situation advice should be obtained from the filter manufacturer).
  • In the affected area, turn on the cold water taps and flush for at least 5 minutes.
  • In the affected area, turn on the hot taps and flush for at least 5 - 15 minutes (longer flushing may be required in large facilities with complex systems). Ensure that flushing of the hot water system does not deplete the stored hot water by monitoring water temperature at hot water outlets during flushing.
  • In the affected area, flush plumbed-in appliances according to manufacturer’s guidelines, including, but not limited to ice makers and chilled water dispensers.
  • In the affected area, flush and clean all other devices that may have used the contaminated water such as, but not limited to: Continuous Positive Airway Pressure (CPAP) devices, humidifiers, coffee makers and water jug filters.

Record keeping

In accordance with your WRMP, record the details of the operational exceedance, including where, when and what was remedially flushed (e.g. tap/shower), by whom and any additional comments (discolouration or unusual odour) should be recorded.


  • Stringent control measures must be implemented to prevent the risk of scalding.
  • Throughout the remedial flushing process, exposure of staff and patients to potentially contaminated aerosols should be minimised.
  • Ensure no outlets are missed. Outlets in vacant rooms or storage areas can easily be overlooked and become reservoirs for contamination of the rest of the system.


Last updated: 24 January 2017