Anyone renting out a property in England has legal responsibilities to assess the risks and take preventative measures where necessary from Legionnaires Disease. Thankfully, it’s comparatively rare in the UK, but when it does strike, it’s serious.
The level of risk in ordinary domestic property is low, but still exists. The Legionella Bacteria which can cause Legionnaire’s disease can breed in any stagnant or pooled water, perhaps in a disused pipe or tank.
One of its nastier tricks is to lurk in a shower head in an empty property and wait for a new tenant to move in. There’s probably more of a risk in older properties, especially Houses of Multiple Occupation, but it can be found anywhere, even in your car’s screen wash reservoir.
You can find more information on Legionella and landlord responsibilities on the Health and Safety Executive’s website.