Legionella risk assessment questions
Straightforward answers to the most common questions about legionella, water hygiene, and compliance in the UK.
Can I do my own legionella risk assessment?
For a simple domestic let or a small commercial premises, yes. ACOP L8 does not require the assessor to be an external contractor. What it requires is competenc...
Do I need a legionella risk assessment?
Almost certainly yes, if you are an employer, a landlord, or in control of any non-domestic premises. The Health and Safety at Work Act 1974 makes the duty univ...
How long does legionella take to develop in water?
Legionella can grow from undetectable levels to a clinically significant population in a matter of days under the right conditions. Warm, stagnant water with a ...
Legionella flushing: how long should I run the taps?
Run hot and cold outlets until the temperature stabilises, then for a further minute at full flow. In practice this usually means two to five minutes per outlet...
Legionella in shower heads: the risk and how to manage it
Shower heads are the highest-risk outlet in most domestic and commercial water systems because they produce a high volume of aerosol directly into the breathing...
What happens if legionella is found in my water system?
Finding legionella at a low count is usually a sign to tighten controls, not a crisis. A count above the action threshold triggers a specific response: disinfec...
What is a legionella certificate?
There is no such thing as an official "legionella certificate" in UK law. The term is shorthand for the written legionella risk assessment that the duty holder ...
What is an anti-legionella valve and when do I need one?
An anti-legionella valve is a thermostatic mixing valve designed to remove stagnant water from the tempered (blended) pipe that runs between the valve and the o...
What to do if legionella is detected
A positive sample is not the same as an outbreak. The action depends on the count and the type of system. Below 100 cfu/litre, review your controls. Between 100...
Who is responsible for a legionella risk assessment?
The duty sits with whoever has control of the premises or the water system. That is usually the employer, the owner, the landlord, or the managing agent. You ca...