Prevention and Treatment of Legionella Outbreaks
Posted by Legionella Regulations on July 29th, 2019
Legionella is naturally occurring microorganism found in fresh sources, like rivers and lakes, wherever the microorganism typically is present in low amounts and does not cause illness. However, bacteria will multiply to dangerous levels under certain conditions and probably cause Legionnaires’ malady, or Legionellosis. People contract this illness by breathing tiny droplets of the contaminated water through mist or vapour.
Legionella bacteria are commonly found in water. The microorganisms multiply wherever temperatures are between 20-45°C and nutrients are accessible. The microorganisms are dormant below 20°C and don't survive higher than 60°C.
Legionnaires’ illness may be a potentially fatal kind of respiratory disorder, contracted by inhaling airborne water droplets containing viable Legionella bacteria. Such droplets can be created, for example, by hot and cold water outlets, atomisers, wet air conditioning plant, and whirlpool or hydrotherapy baths. Anyone can develop Legionnaires’ disease, but the elderly people, children and those with cancer, diabetes or chronic respiratory or kidney disease are at more risk.
What needs to be done?
Health and social care providers like Hydrochem, as per Legionella Regulations, carry out a full risk assessment with legionella cooling tower water treatment systems and ensure adequate measures are in place to control the risks.
Using temperature control-
The primary technique used to management the chance from Legionella is water temperature management. Water services should be operated at temperatures that stop bacteria growth:
* Hot water storage cylinders (calorifiers) should store water at 60°C or higher
* Hot water should be distributed at 50°C or higher (thermostatic mixer valves need to be fitted as close as possible to outlets, where a scald risk is identified).
* Coldwater should be stored and distributed below 20°C.
Doing Regular Inspection-
A competent person should routinely check, inspect and clean the system, in accordance with the risk assessment. The ‘sentinel’ outlets (furthest and nearest to every tank or cylinder) for monthly checking of the distribution temperatures need to be determined. The certified person should additionally check the hot water storage cylinder temperatures monthly and cold storage tank temperatures at least every six months.
Stagnant water favours Legionella growth. To reduce the risk, the dead ends in pipe-work must be removed, infrequently used outlets (including showerheads and taps) should be flushed at least weekly, and showerheads and hoses must be cleaned and de-scaled at least quarterly.
Cold-water storage tanks should be cleansed sporadically, and water should be drained from hot water cylinders to examine for scrap or signs of corrosion.
Designing systems to minimise Legionella growth by-
* Keeping pipe work as short and direct as possible.
* Adequately insulating pipes and tanks.
* Using materials that do not encourage the growth of Legionella.
* Preventing contamination by fitting tanks with lids and insect screens.
Additional controls-
Water samples should be analysed for Legionella periodically to demonstrate that bacteria counts are acceptable. The frequency should be determined by the level of risk, in accordance with the risk assessment.
Other control methods-
Other strategies to manage bacteria include copper and silver ionisation and biocide treatments (e.g. chlorine dioxide). To ensure that they continue to be effective, their application will need appropriate assessment as a part of the general water treatment programme as well as correct installation, maintenance and observance.
Hydrochem, Australia’s leader in industrial and commercial legionella cooling tower water treatment, since 1977, has set up a website on Legionella Regulations to create awareness regarding the NSW Legionella Laws.
