Water safety guidance for tenants in commercial units
Legionnaires' disease is rare but potentially a fatal illness. It’s caused by breathing in small droplets of water that contain the Legionella bacteria. This can lead to a cough, high fever, shortness of breath, and muscle aches.
While it’s associated with large buildings, like hotels, hospitals, and office blocks, Legionella can also grow in your home, especially where water sits still or isn’t used often. This could include unused taps, shower heads, and garden hoses.
Anyone can be affected, but some are more vulnerable:
- over 45 years old
- smokers or heavy drinkers
- people with lung, kidney, or immune system related issues
Where does Legionella come from?
Legionella bacteria are naturally found in water. In small amounts, they’re usually harmless. However, inside buildings, they can grow quickly in:
- Warm water (between 20 °C and 45 °C)
- Stagnant water that hasn’t moved for a while, which allows sludge, rust, or scale to settle in one place. This gives the bacteria the nutrients it needs to grow.
- Dirty shower heads or taps where bacteria can multiply.
What you can do
Simple and easy precautions can help keep your water clean and safe:
Keep your hot water hot
- Hot water should reach at least 50 °C at the tap within one minute of running.
- Stored hot water should reach 60 °C for at least one hour a day.
- Don’t alter your boiler or hot water settings. They are set to maintain safe temperatures.
Keep your cold water cold
- Cold water should stay below 20 °C.
- If it feels warm after running for two minutes, investigate or seek advice from a qualified professional.
Keep water moving
Run all taps and showers, and flush toilets at least once a week, especially if they haven’t been used for seven days or more.
Keep things clean
Clean shower heads and taps every three months, or more often if needed. A standard store-bought disinfectant works well for cleaning.
If you can’t remove the shower head, cover it with a plastic bag, let the water run into the bag, then pour the water away slowly. This will help reduce spray and minimise risk.
Thermostatic Mixing Valves (TMVs)
TMVs are devices that control water temperature to prevent scalding. If your unit has these, they must be checked regularly to make sure they’re working properly.
To reduce the risk of Legionella, TMVs must be regularly monitored, maintained and inspected in line with the manufacturer's recommendations to ensure they are functioning correctly.
Vacant units
If your unit has been empty for more than a week:
- Run all taps and showers slowly for one minute to reduce aerosol droplets, then fully open and run for four minutes. Adjust flow to prevent overflow.
- Flush toilets twice with the lid down before use.
Responsibilities and access
As a commercial tenant, you are responsible for managing water safety within your unit. This includes:
- monitoring water temperatures
- running unused taps and showers
- cleaning fittings
- maintaining any water-related equipment
- investigating and resolving any issues with your water system
Further guidance from the Health and Safety Executive (HSE)
For more detailed information on managing water safety and understanding Legionnaires' disease, you can access helpful resources from the Health and Safety Executive (HSE). Please visit their website for practical advice on managing risks in commercial properties.