Legionella Risk Assessment for Scotland Landlords

Legionella risk assessment is one of the landlord obligations that generates the most confusion — partly because it sounds like it requires expensive lab testing, and partly because the requirement itself is simpler than most people assume.

What the Law Requires

Under the Health and Safety at Work etc. Act 1974 and the Control of Substances Hazardous to Health Regulations 2002 (COSHH), you must identify and assess the risk of legionella bacteria exposure in your rental property's domestic water system.

This is also part of the repairing standard framework under the Housing (Scotland) Act 2006, since it affects water installations under Section 13(1)(c).

What a Domestic Risk Assessment Covers

For a standard residential let with a conventional domestic water system, the risk assessment evaluates:

Water storage — is there a cold water storage tank? If so, does it have a tight-fitting lid and adequate insulation? Open or poorly insulated tanks are the primary domestic legionella risk.

Temperature control — hot water should be stored at 60°C or above and distributed at 50°C or above. Cold water should be below 20°C. Legionella bacteria multiply most rapidly between 20°C and 45°C, so a system that maintains these temperature boundaries significantly reduces risk.

Dead legs and infrequently used outlets — pipework sections that carry water but are rarely flushed (a capped-off shower, a basin in a room nobody uses) can harbour stagnant water. Note every outlet and how frequently it's used.

Showerheads — descale and clean between tenancies. Biofilm buildup in showerheads is a known risk factor.

You do not need to submit this assessment to any authority. HSE guidance does not require most domestic landlords to keep a written record of the findings, but a concise record is useful evidence of the assessment and any action taken.

Do You Need Commercial Lab Testing?

For most standard residential lets — no. HSE guidance does not require routine annual sampling or commercial Legionella certificates for domestic water systems.

If your assessment identifies an uncontrolled risk, seek competent advice on suitable control measures. A complex communal water system may warrant specialist assessment, but high-risk features do not by themselves create a blanket legal requirement for commercial testing.

A standard 1–2 bedroom flat with a combi boiler and no cold water tank is generally low-risk. The risk still needs to be assessed, but routine water sampling is not required.

Who Can Do It

You can carry out the risk assessment yourself if you're competent to do so — meaning you understand the legionella risk factors and know what to check. There's no statutory requirement for a specialist assessor in domestic settings.

If you're not confident, a plumber or water hygiene specialist can do it. Expect to pay £50–£150 for a straightforward domestic assessment.

How Often to Review

Review the risk assessment when the water system changes (new boiler installation, plumbing modifications, addition of a shower). A change of tenancy is a practical opportunity to review it; there is no fixed annual or biennial cycle.

Practical Steps Between Tenancies

• Run all taps and showers for at least 2 minutes to flush standing water, especially if the property has been vacant
• Descale showerheads
• Check the hot water temperature at the nearest tap to the cylinder — it should reach 50°C within a minute
• Verify cold water at the kitchen tap is below 20°C
• Document everything with dates

The Risk of Ignoring It

Legionella risk assessment rarely comes up in tribunal hearings — gas safety and damp are far more commonly disputed. If a tenant develops Legionnaires' disease, you may need to show that you assessed and controlled the risk; a written record is helpful evidence. The assessment takes 30 minutes for a standard flat. There's no reasonable excuse not to assess the risk.

For a legionella self-assessment template, temperature recording log, and how water safety fits into the wider repairing standard compliance framework, see the Scotland Repairing Standard guide.

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