How Long Does a Legionella Risk Assessment Last?

Landlords, letting agents, and facilities managers frequently ask us for the "expiry date" on their Legionella paperwork. Unlike an annual Gas Safety Certificate or a 5-year EICR, there isn't a single statutory expiry date stamped on a Legionella Risk Assessment. But do not let that fool you into thinking the certificate lasts forever.

Assuming that a Legionella Risk Assessment is a one-off task is a common and highly dangerous trap. The UK Health and Safety Executive (HSE) does not give water hygiene assessments a neat calendar expiration. Instead, they use a phrase that catches out thousands of landlords every year: the assessment must be "kept under regular review."

If you hand an outdated, unreviewed certificate to a local council inspector or insurance adjudicator, they will treat it as if you have no certificate at all. Here is exactly how long your assessment is valid for, and the hidden triggers that require you to renew it immediately.

The "Two-Year" Industry Standard

While the HSE ACoP L8 guidelines do not explicitly say "renew every 24 months," a two-year review cycle has become the absolute minimum industry standard for compliance.

Why two years? Because water systems degrade over time. Scale builds up on showerheads, providing a food source for bacteria. Boiler thermostats drift, meaning hot water might no longer be reaching the critical 50°C needed to kill Legionella. The majority of local authorities and HMO licensing boards across the UK will reject any risk assessment that is older than 24 months as a matter of policy.

The Compliance Trap: 4 Triggers That Invalidate Your Assessment Instantly

Here is the trap that most property managers fall into. Even if your assessment is only six months old, certain events will instantly invalidate it. The HSE states that you must commission a completely new assessment if there is a "significant change" to the commercial premises or residential property. These triggers include:

1. A Change of Tenancy

A new tenant means a new risk profile. If the new occupant is elderly, immunocompromised, or has young children, they are highly susceptible to Legionnaires' disease. Your previous assessment (based on a healthy, younger tenant) is no longer legally sufficient.

2. The Property Was Empty (Void Periods)

If your property sits empty between tenancies for more than a few weeks, the water in the pipes stagnates. Stagnation is the number one cause of Legionella proliferation. An assessment conducted before a long void period is legally useless; you must have the system flushed, potentially chlorinated, and re-assessed before a new tenant moves in.

3. Changes to the Plumbing System

Did you install a new combi-boiler? Remove an old cold-water storage tank? Cap off a pipe to remove a bathroom sink? Any physical alteration to the water system creates the potential for new "dead legs" (stagnant pipes). Your old assessment is immediately void.

4. A Loss of Temperature Control

If you or your tenants notice that the hot water is no longer getting consistently hot, or the cold water runs warm in the summer, you have lost control of the primary Legionella defence mechanism. You must order an urgent re-assessment.

Maintaining Total Property Compliance

Managing renewal dates is one of the hardest parts of property compliance. Water hygiene is just one facet of your statutory duties. To remain fully legally compliant and protect your tenants, you must also keep on top of your electrical and fire safety expiration dates.

If your Legionella Risk Assessment is older than 24 months, or if your property has undergone any of the changes listed above, you are legally exposed. Use our priority quote form below to book a fresh, fully compliant assessment from our accredited nationwide network today.