Legionella Prevention During Lockdown

7 Helpful Tips to Recommission Lockdown Buildings to Prevent Legionella

Article 2 of 3

During these challenging times, many buildings are currently not in use such as offices, schools, museums, sports centres and holiday parks. Water services that have low use and stagnant areas have an increased potential risk for legionella growth. On the other hand, hospitals, nursing homes, and residential care are in operation and are 100% focused on the health and care of their patients. In both situations (lockdown or not lockdown building) extra precautions must be undertaken to protect their exposure to Legionella bacteria.

In last week's article, we mention your legal duties and how a Legionella Risk Assessment can help you to prevent legionella.

In article 2 of 3, we provide multiple tips to recommission lockdown buildings to prevent legionella.

Legionella Bacteria in London

Legionella bacteria may grow in any system containing water, such as cooling towers and hot and cold water services. They survive low temperatures and thrive at temperatures between 20°C-45°C, especially where there is scale, corrosion and high microbiological load.

Enhanced Water System Flushing - Legionella Prevention in London

1. Enhanced flushing
This should be introduced on the floors and areas that have now become vacant or empty, so effectively adding additional outlets to the little-used outlet list which are then covered by the existing weekly flushing regime.

2. Check boiler set point > 60 degC
Legionella growth also includes hot water flush of drinking water systems. To prevent this, please check if your boiler temperature set point is >60degC.

3. The frequency of flushing
This may be increased to twice weekly or more to ensure sufficient flow through the entire system.

4. Reduce the storage level (consult NIJHUIS DEBA before doing this!)
If the amount of flushing is found to be insufficient to provide good turnover in any water storage tank then have you considered reducing the storage level. You should check that your tank is suitable to have the level reduced as some are designed to operate at full capacity only and reducing levels may introduce structural defects.

5. Drain the systems
The draining of systems is usually not considered for periods of less than 30 days. Draining systems also introduces air which has the potential to increase corrosion. Drained systems are difficult to recommission and may have mechanical issues resulting from the drain down.

6. Think before recommissioning the building
When the time comes to recommission the building, we would advise flushing the outlets before taking a set of Bacterial samples. (Total Viable Count 220C, Total Viable Count 370C, E Coli and Coliform) across site to determine the condition of the water quality. This should give a good indication of the health of the system compared to historical records. Additional Legionella sampling should be considered where the system is particularly complex or has a history of poor control or where vulnerable people are exposed.

Drain water systems to prevent legionella
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7. Follow-up actions after recommissioning
Based on the results from these samples the possible actions are shown below.

  • If all samples are satisfactory and the count results are within 900 cfu/ml of the incoming water level count, then the water system can be put back into service.
  • If the sample results are unsatisfactory with a count in excess of 900 cfu/ml of the incoming water level count or pseudomonas aeruginosa, Coliform or Legionella bacteria are present, then either resamples should be taken to verify conditions or disinfection of the system should be considered.
  • Your NIJHUIS DEBA consultant can advise on which method of disinfection is most appropriate for the system.

In the next article which will be published the coming weeks, we will provide the "Nijhuis Industries Permanent Legionella Solutions".

Can't Wait?

Contact the NIJHUIS DEBA Legionella experts: sales.deba@nijhuisindustries.com (UK)
or visit: https://www.nijhuisindustries.com (International)