Safety and first aid

Swimming pool contamination

Contaminated swimming pools can be a:

  • source of odours and bacteria
  • breeding place for mosquitoes
  • risk to people who use them.

Swimming pools should either be emptied or kept chlorinated to prevent the water quality from deteriorating.

After a bushfire or flood, your swimming pool may contain debris including ash. This may affect the chemical balance of the water, making the pool unsafe.

Several actions may need to be undertaken before your pool is safe to use again. 

If the pool can be emptied?

To determine whether your pool can be emptied following damage by a bushfire or flood, advice from a building consultant may be required.

Emptying a pool situated in an area with a high water table or in water-logged soils may put the pool walls under stress.

Potentially contaminated pool water needs to be disposed of to a location where it will not cause overflow or contaminate other water bodies.

When emptying a pool, the water needs to be disposed of by a method approved by your local government. The water must not be discharged:

  • into the sewer without approval from the service provider.
  • into an onsite wastewater system without approval from the local government.
  • to a location where it will cause overflows in already flooded/overloaded drainage systems.

If it is safe to empty the pool:

  • all water and residue should be removed
  • flush plumbing pipes and replace filters
  • clean and sanitise the pool floor and walls

Once completely cleaned, the pool can be refilled using scheme water. Disinfectant can be added to bring the pool up to the operating parameters.

Where a pool cannot be emptied

For pools unable to be emptied, a trained technical operator will need to inspect the pool and determine an appropriate treatment to remove solids from the water.

Depending on the amount and type of inundation, the water may need to be treated over several days. Qualified operators should determine the time required for waste removal, chemical treatment process and chlorination to achieve the required filtration of pool water.

After all the solids have been removed from the pool, you can start super-chlorination.

The pool and filters should be super-chlorinated to 20mg/l (ppm) for up to 13 hours.

Depending on the amount of contamination and the volume of the pool, the chemical treatment process and chlorination of the pool may take up to one week to complete.

Once the pool water is visibly clean, the pool motor and filter(s) can be used to operate at the required chemical levels (chlorine, pH, bromine, cyanuric acid level).

Four complete cycles of the pool water (circulated through the treatment system) are required to achieve 98 per cent filtration of pool water. A trained pool technician will be able to determine a complete filtration cycle.

Sampling swimming pool water

If the above measures are followed, the water should be safe to swim in. You may verify the microbiological water quality of your pool using an independent water sampling service by a trained pool technician. The samples should be tested by a National Association of Testing Authorities (NATA) accredited water laboratory.

Read more about maintaining water quality in swimming pools and spas.

Last reviewed: 13-10-2023

This publication is provided for education and information purposes only. It is not a substitute for professional advice. Information about a service, product or treatment does not imply endorsement and is not intended to replace professional advice. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified professional for answers to their questions.

Questions? Ask your local government environmental health services