Water disinfection and Legionella

Updated: Feb 18

Last year in Australia there were 544 cases of Legionellosis reported, which was slightly higher than the 5 year average (source: Australian Department of Health). Victorian Department of Health believes that #Legionella accounts for 5 to 15% of #pneumonias. The disease is generally acquired through the inhalation of contaminated aerosols from water systems. The source of the Legionella hazard and corresponding risk assessments are part of public health water risk management plans for buildings across Australia and world-wide.



The conditions suitable for Legionella bacteria are:
  •  Water temperatures 20 to 50 degrees C

  •  Low flow rates or low turnover of water

  •  Poor water quality

  •  Nutritional sources like algae, rust, sludge, organic matter


Mitigation of the Legionella risk usually includes:
  •  clean water sources with #disinfection to more than 0.5 mg/L

  •  keeping water under 20 degrees C or over 60 degrees C

  •  removal of pipework dead legs

  •  general maintenance and cleaning

Among other actions, mitigation for Legionella in buildings requires ongoing measurement of #waterquality, especially disinfection levels and temperature of:
  •  the incoming water supply,

  •  water storage and delivery pipes, and

  •  water cooling towers.


Often measurement every 30 days is specified in risk mitigation plans. This is not effective

#riskmitigation because disinfection levels and temperature do not remain constant for 30 days.

Running such risk mitigation operations manually is extremely expensive, leads to error prone data

and is not timely. Often customers #drinking contaminated undisinfected water know about the

problem first, resulting in time consuming complaints and firefighting. Near real-time frequent

measurement is effective and required.


It is proposed that effective mitigation needs at least measurement every 5 minutes as an example for:

  •  the water quality at strategic points in a water storage and water delivery infrastructure, and

  •  the water temperature in pipes throughout buildings.

The process is suited to remote robots measuring the required water parameters and securely

communicating back to big data warehouses. A system is required for real time alerts, trend

reporting, interactive reporting, tools to analyse data outliers, inclusion of external influences like

weather, and more. (Some organisations may prefer to outsource the whole operation.)


With robotic technology after one year of water quality measurement, an accurate picture of water

quality will emerge. The picture will become a base that is built upon real data enabling the system

to become intelligent, facilitating fast and effective preventive action to maintain water quality.


Each building being monitored has different infrastructure and circumstances resulting in a different

“water quality” picture, just like a fingerprint or a signature.


The signature of each building empowers risk mitigation, improving duty of care and reducing risk to human health due to bacteria or other water impurities, and not just from Legionella.


While this may seem a considerable task, risk mitigation plans for many buildings requires it to be

done manually and as already discussed on a completely inadequate 30 day cycle. The costs of

manual risk management solutions are many times larger than robotic technology solutions.


Theneffectiveness and accuracy of robotic technology can not be matched by manual solutions. For

effective duty of care, there is little choice.


Such robotic solutions exist and are proven. TracWater has installed such a system on the Gold Coast

in 2017, providing a signature of water quality in key locations and infrastructure before the 2018

Commonwealth Games.


TracWater has developed similar signatures at hospitals for the Queensland Department of Health.

However these went one step further.


Plug and play portable robots were placed in buildings to measure water quality and temperature in near real-time at various locations, like taps near high- risk rooms.


At each location the data was automatically collected further detailing signature information.


Any data outliers from the signature data can be alerted. This is an effective solution to

mitigate health risk and pro-actively reduce contaminations at potential blind-spots.


If these issues are considered in your risk mitigation activities, TracWater would be honored to

listen to you. www.tracwater.com.au


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