SaroxaiLegionella risk assessment: a landlord's guide
Legionella is one of those duties that sounds alarming and is regularly oversold. Landlords do have to assess and control the risk in a property's water system, but for an ordinary house or flat that's a straightforward job you can usually do yourself, without paying for anything called a "certificate". Here's what the duty actually is, when you might want a professional, and the simple steps that keep the risk down.
What's in this guide
What legionella is, and the duty
Legionella are bacteria that can grow in water systems and, if breathed in as a fine spray, cause Legionnaires' disease. They multiply in still, lukewarm water, roughly between 20°C and 45°C, which is why the whole approach to control is about keeping water either properly hot or properly cold and stopping it sitting around. As a landlord you have a duty under health and safety law to assess and control that risk for your tenants. For most homes, that duty is met with a sensible assessment and a few habits, not an expensive intervention.
Do you need a professional?
Usually not. For a typical residential letting, a landlord who understands the water system can carry out the assessment themselves by following the recognised guidance. Bringing in a specialist makes sense when the system is larger or more complex, for example a property with big stored-water tanks, a communal or shared system, or occupants who are more vulnerable to infection. If someone is pushing costly water sampling for an ordinary flat, be sceptical.
How to assess the risk
A basic assessment is really a walk through the water system, looking for the conditions the bacteria like:
- Water that sits at lukewarm temperatures rather than clearly hot or cold.
- Stored water, such as cold-water tanks or older hot-water cylinders.
- Infrequently used outlets, like a spare bathroom or an outside tap, where water stagnates.
- Showerheads and spray taps, which can create the fine mist that spreads the bacteria.
- Dead legs — lengths of pipe that no longer go anywhere and hold standing water.
Note what you find, and it usually points straight at what to fix.
How to control it
The controls are simple and mostly free:
- Keep hot water hot — a hot-water system that reaches around 60°C.
- Keep cold water cold — below about 20°C.
- Flush unused outlets regularly, and especially before a new tenant moves in or after the property has stood empty.
- Clean and descale showerheads periodically.
- Remove dead legs where you reasonably can, so water isn't left standing.
- Brief your tenants to run taps and showers through if the property has been empty for a while.
The 'certificate' myth
This one causes a lot of unnecessary spending. There is no legal requirement to hold a "legionella certificate" for a normal domestic rental. The law asks for a proportionate risk assessment and sensible control measures, reviewed from time to time or when something changes, and a note that you've done it. That's it. Keep your own dated record of the assessment and the controls you have in place, and you've met the duty without buying a document you never needed.
One place for the whole property.
Property Hub keeps your assessments, certificates, key dates and documents together per property — in your own iCloud, with reminders before renewals fall due.