Legionella risks in empty/low use commercial premises
In vacant properties water can stagnate within water systems. As a general principle, outlets on hot and cold water systems should be used at least once a week to maintain a degree of water flow and to minimise the chances of stagnation. To manage the risks during non-occupancy, consider a suitable flushing regime or draining the system if it is to remain vacant for long periods. The HSE provides further guidance.
For other water systems that are no longer in use, such as leisure, sports and swimming and spa pool facilities, you should follow the procedures described in the Pool Water Treatment Advisory Group Code of Practice.
The European Society for Clinical Microbiology and Infectious disease have provided guidance on managing Legionella in building water systems during the COVID-19 pandemic.
If you have your water services system maintained by an outside contractor you should ensure that they are competent in legionella management, one method of ensuring this is to enquire as to whether they are members of the Legionella Control Association. They also provide guidance on the safe management of water systems during the Covid–19 outbreak.