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Landlord glossarySafety

Legionella Risk Assessment

A written assessment of the risk of legionella bacteria in the property's water system. Required by HSE under the Control of Substances Hazardous to Health Regulations 2002. Not a formal certificate, but landlords must demonstrate they have considered the risk.

Reviewed by Erdem VolkanLast reviewed 16 September 2026How we check facts

Required by
HSE under COSHH 2002
Form
Written assessment (not a certificate)
Frequency
Review when circumstances change

Why it matters

What Legionella Risk Assessment means for a landlord

Legionella is a low-probability, high-consequence hazard, an outbreak is rare but a death is prosecutable under HSE legislation. Most small residential properties are low-risk (cold water tanks drained, regular use) but the landlord still has to produce a dated written assessment showing they considered it. A one-page risk assessment kept in the property file closes the duty.

Worked example

How it plays out

Beth takes over a house in Exeter that has been empty for two months. Before the tenant moves in, she runs every tap and the shower for several minutes to flush the system, checks the hot water from the combination boiler runs hot quickly, and writes a short risk assessment noting the simple system and the flushing. She gives the tenant plain advice on keeping the showerhead clean and reporting any problems with hot water.
An illustrative example. Names, places and figures are made up.

Common mistakes

Where landlords go wrong

  1. 01Believing a legionella test certificate is required, when the duty is to assess and control the risk.
  2. 02Not flushing the water system after the property has stood empty.
  3. 03Leaving an unused shower or tank in the system.
  4. 04Having no written record that the risk was considered.

What to do

A short checklist

  • Write a short risk assessment for each property.
  • Flush taps and showers after any empty period.
  • Remove redundant pipework or tanks where practical.
  • Give tenants basic advice on hot water and showerheads.