Legionella Guard – Competence

Legionnaires’ Disease and Legionellosis

Legionellosis is a collective term for diseases caused by Legionella bacteria, including the most serious form, Legionnaires’ disease, and the less severe conditions of Pontiac fever and Lochgoilhead fever.

Legionnaires’ disease is a potentially fatal form of pneumonia. While anyone can be susceptible to infection, the risk increases with age and is higher among individuals over 45, smokers, heavy drinkers, and those with chronic respiratory or kidney disease, diabetes, heart or lung disease, or a weakened immune system.

Legionella pneumophila and related bacteria are commonly found in natural water sources such as rivers, lakes, and reservoirs. They may also be present in man-made water systems, including hot and cold water systems and spa pools. Where conditions are favourable, bacteria can multiply, increasing the risk of Legionnaires’ disease.

Infection usually occurs through inhalation of contaminated water droplets (aerosols), particularly from showers and spa baths. There is no risk from drinking contaminated water.

The Need for a Legionella Risk Assessment

Following changes to the Approved Code of Practice and Guidance (ACOP), the requirement for Legionella risk assessments now includes smaller water systems and storage tanks of less than 300 litres. This places additional responsibilities on landlords and managing agents.

The guidance states that all water systems require a risk assessment, although not all systems will require extensive control measures. Where risks are identified as low and are being properly managed, further action may not be necessary. However, assessments must be reviewed regularly and whenever there is reason to believe they are no longer valid.

Legal Framework

The requirement to assess and control Legionella risk is governed by several pieces of legislation, including:

• The Housing Health and Safety Rating System (HHSRS) Implemented in April 2006 under the Housing Act 2004
• Landlord and tenant act 1988
• Renters rights bill 2025
• Housing Act 2004
• Defective Premises Act 1972
• Homes (Fitness for Human Habitation) Act 2018
• Common Law Negligence
• control of hazardous substances out (COSHH).

Failure to comply with these legal duties may result in enforcement action, high financial penalties, or prosecution for criminal negligence.

This Guidance

This guidance provides practical advice and a simple framework for producing a Legionella risk assessment suitable for low-risk domestic properties, including those with combination boilers or basic hot water storage systems used daily.

While risk assessments are not always legally required to be recorded in writing, ACOP guidance strongly recommends documenting all assessments. Written records provide clear evidence of compliance in the event of inspection.

WITHOUT written records it will be difficult to show that the assessment has been carried out and this could lead to prosecution

Who Should Carry Out the Risk Assessment?

ACOP requires that a competent person carries out the risk assessment. In low-risk situations, landlords or small agents may undertake the assessment themselves, provided they are competent to do so.

Where risks are higher, properties are more complex, or confidence is lacking, the appointment of a specialist assessor is recommended.

The duty holder is usually the landlord, though this role may also be assumed by a managing or letting agent. The duty holder may appoint a responsible person to carry out routine control measures identified in the assessment.

It is acceptable for the duty holder to request assistance from competent professionals, such as gas engineers or plumbers, during routine safety checks to identify risks including storage tanks, dead legs, and water temperatures.

A reasonable person with a brief knowledge of water bacteria , how it grows and we=here should be able to assess the risks quickly and easily.

Identifying the Risk

A Legionella risk assessment must identify potential sources of exposure and determine suitable measures to prevent or control the risk.

• Presence of Legionella bacteria
• Water temperatures between 20°C and 45°C
• Stagnant water, sludge, scale, rust, algae, or biofilms
• Aerosol generation from outlets such as showers or spa pools
• The circumstance of the tenant ( ie age or risk levels)

Key Considerations in Domestic Properties

• Mains-fed water systems are generally low risk
• Combination boilers reduce risk due to minimal water storage
• Cold water tanks must be clean, insulated, and fitted with tight lids
• Hot water cylinders increase risk, particularly during void periods
• Fortic tanks present a high risk and should be removed where practicable
• Dead legs should be identified and removed
• Water temperatures must be measured and recorded
• Outside taps or little used outlets need to be flushed before use

Preventing and Controlling the Risk

Water Storage

Water storage tanks should be recorded, clean, insulated, and fitted with secure lids. Tank water temperatures should be kept below 20°C. Inspections must only be carried out where safe access is available it is there access by a fixed ladder and the loft is boarded so easy to inspect safely.

Dead Legs

Any dead legs should be recorded and removed, as stagnant water encourages Legionella growth.

Water Temperatures

• Hot water storage temperature: 60°C
• Hot outlet temperature: above 50–55°C
• Cold outlet temperature: below 20°C
• Temperatures above 60°C should be avoided to reduce scalding risk

Tenant Information

Tenants should be advised to run infrequently used outlets weekly, clean shower heads at least quarterly, and follow guidance during extended absences. Providing an information leaflet meets ACOP recommendations we have included an information sheet for tenants with your report.

Spa Pools and Hot Tubs

Spa pools and hot tubs present a high risk due to operating temperatures and aerosol generation and should ideally be removed. Where present, occupiers must disinfect after every use.

Void Periods and Change of Tenancy

During void periods, outlets should be flushed weekly. Where properties are vacant for more than six weeks, the system should be heated and flushed thoroughly. At a change of tenancy, temperatures and system conditions must be rechecked.

Recording and Reviewing the Risk Assessment

All findings, control measures, and remedial actions should be recorded. Where risks are insignificant and adequately controlled, no further action may be required.

Risk assessments should be reviewed at least annually and whenever changes occur, including:

• Changes to the water system or its use
• Changes in building use
• New information on Legionella risks
• Ineffective control measures
• Changes in responsible personnel
• A case of Legionnaires’ disease associated with the property

Summary – Key Points of a Simple Risk Assessment

• Hot water temperature above 55°C at outlets
• Cold water temperature below 20°C
• Hot water storage set to 60°C
• Cold water tanks in good condition with tight-fitting lids
• No debris, dead legs, or uninsulated pipework
• Safe access to lofts noted where applicable
• Thermostatic radiator valves fitted where appropriate
• Look for little use outlets and advise to flush regularly
• Consider the tenants age and health to se if heightened risk