As businesses begin to reopen they must consider the risk posed by harmful bacteria and hazardous chemicals in any water system left idle during the COVID-19 closure. Employers and those in control of buildings must put in place measures to reduce these risks as far as practically reasonable.
All buildings that have been closed for a period of time and that have a water supply are potentially at risk.
The problem
Drinking water and hot water systems rely on the constant supply of fresh mains water to keep them clean and wholesome. Problems can arise when the water supply is interrupted or the system is not used for a period of time. Water which has sat in pipes may allow harmful bacteria like Legionella (the cause of Legionnaires’ disease) to grow and then infect people when they inhale the tiny drops of water created when running taps, taking showers or washing hair.
Legionnaires’ disease is a serious respiratory infection with a high death rate. Unless water systems are maintained, the closure of buildings due to COVID-19 restrictions will allow the growth of Legionella to levels which may cause illness when buildings are reopened. The problem can increase in the summer months when warmer temperatures encourage the growth of the bacteria.
Unused water tanks, plumbed-in appliances, shower heads and dead-legs in pipework are all risk areas. Wet cooling systems are a particular concern as they work by generating and dispersing large amounts of water vapour into the air which can be breathed in by people just passing by.
Contamination of hot and cold water systems can also arise from metals or other chemicals that can leach into the water from pipework, plumbing materials and ground sources, a concern in Norwich where many older buildings still have lead pipes.
Controlling hazards in water systems
Many smaller buildings will find the control measures are often straightforward however much will depend on how complex the water system is. Simple control measures may include cleaning and descaling taps and shower heads, draining down and refilling cold water systems, or flushing through with very hot water to disinfect hot water pipes. Complex water systems such as cooling towers, swimming pools and spa pools will always require specialist help and guidance.
Employers, landlords and others in control of buildings may all have specific responsibilities under health and safety legislation. Employers must have a health and safety risk assessment and if employing five or more people this assessment must be written down. If the business has a water supply the risk assessment should already include the hazard posed by Legionella.
If you are unsure about what is required you will need to seek expert help.
What should businesses do next?
- Understand the components of the water system and all the associated fittings and plumbed-in appliances within the building.
- Determine what must happen for every component in the system to be returned to use safely.
- Pay particular regard to places where Legionella can grow, like storage tanks and dead-legs in pipework where fittings have been removed.
- Give special attention to plumbed-in equipment that generates water droplets like showers, spas and wet cooling towers.
- Have regard to people that are especially vulnerable like the elderly.
- Get expert help and advice if you are at all unsure.
- Consider taking water samples to verify the system is free of Legionella.
- Review your health and safety risk documentation to ensure it adequately covers the hazards posed by Legionella and other contamination.
- Keep records of what you have done.
Further help and guidance
The Health and Safety Executive (HSE) has produced useful guidance on controlling Legionella.
Water UK has produced a guide on recovering drinking water supplies after shutdown.
The European Study Group for Legionella Infections (ESGLI) has issued specific guidance on managing Legionella in buildings and offices that have shut down due to the pandemic.
The European Society of Clinical Microbiology and Infectious Diseases (ESCMID) produces an online magazine with regular updates.
