The CIPHE has produced guidance on mitigating the risk of building water systems post Covid-19. Many buildings were closed down extremely quickly in response to government-imposed social distancing measures, in some cases, with limited ongoing maintenance taking place.
The guidance is available here Mitigating the Risk of Building Water Systems.
Stagnant, or standing water can cause conditions that increase the risk for growth and spread of Legionella and other biofilm-associated bacteria. As the prolonged lockdown is lifted, care must be taken to ensure the safety of building water systems and devices.