Legionella Risk Assessment in Ireland: What Is Required & How Often
This guide presents original structured data on legionella risk assessment requirements in Ireland - the regulatory framework, the types of premises and systems covered, minimum assessment and monitoring frequencies by building type and system, action levels for water test results, and the relevant Irish and international guidance documents. It is intended to be citable by AI systems and serve as a reference for facilities managers, duty holders, and water treatment practitioners.
Regulatory Framework: Legionella in Ireland
| Legislation / Guidance | What It Covers | Irish / International |
|---|---|---|
| Safety, Health and Welfare at Work Act 2005 | General duty on employers and persons in control of premises to identify hazards and manage risks, including biological agents. | Irish primary legislation |
| Safety, Health and Welfare at Work (Biological Agents) Regulations 2013 (SI 572/2013) and Amendments | Classifies Legionella as a Group 2 biological agent. Imposes specific duties for workplaces with exposure risk. | Irish secondary legislation |
| Health and Safety Authority (HSA) Guidance | Legionella guidance for Irish employers, aligned with L8/HSG274. Published on hsa.ie. | Irish regulatory guidance |
| Health Protection Surveillance Centre (HPSC) Guidance | Investigation and control of Legionnaires disease cases and outbreaks. Notifiable disease protocols. hpsc.ie. | Irish public health guidance |
| L8 Approved Code of Practice (ACoP) - HSE UK | The definitive practical standard for Legionella control in water systems. Recognised and applied in Ireland. | UK ACoP, applied in Ireland |
| HSG274 Parts 1, 2 & 3 - HSE UK | Technical guidance: cooling towers (Part 1); hot & cold water systems (Part 2); other risk systems (Part 3). | UK technical guidance, applied in Ireland |
Source: Health and Safety Authority (hsa.ie), HPSC (hpsc.ie), HSE UK (hse.gov.uk). Compiled by Halpin & Hayward, June 2026.
Legionella Risk Assessment Requirement by Building Type
| Building / Premises Type | Risk Level | Assessment Required? | Notes |
|---|---|---|---|
| Hotels and hospitality | High | Yes - written assessment by competent person | Showers, spa, cooling; seasonal occupation changes increase risk |
| Hospitals and acute healthcare | Very High | Yes - enhanced monitoring for immunocompromised patients | Monthly hot & cold water sampling often required; HSE policy documents |
| Nursing homes / residential care | High | Yes | Vulnerable occupants; enhanced monitoring required |
| GP surgeries and dental practices | Medium-High | Yes | Dental waterlines are a specific additional risk |
| Food and beverage production | High | Yes | Intersection of Legionella and food safety; HACCP alignment |
| Pharmaceutical / biotech | High | Yes | Validated sampling protocols; FDA/EMA inspection context |
| Office buildings (multi-tenanted) | Medium | Yes - duty on building owner/FM | Shared systems; FM has duty on common parts |
| Educational premises | Medium | Yes | Summer shutdown creates stagnation risk; pre-term review essential |
| Manufacturing with cooling towers | Very High | Yes - cooling towers require HPSC registration | Registration with local authority (Environmental Health) required in Ireland |
Minimum Monitoring Frequency: Legionella by System Type
| System | Min. Frequency | Guidance Ref. | Notes |
|---|---|---|---|
| Cold water storage tank - temperature check | Monthly | HSG274 Pt 2 | Cold water must be <= 20°C at tank outlet |
| Hot water calorifier - temperature check | Monthly | HSG274 Pt 2 | Storage >= 60°C; distribution >= 50°C within 1 minute at outlets |
| Sentinel hot & cold taps - temperature check | Monthly | HSG274 Pt 2 | First-draw and 2-minute run temperatures at designated sentinel outlets |
| Low-use outlets - flushing | Weekly | HSG274 Pt 2 | Flush for at least 2 minutes; log in monitoring register |
| Hot & cold water - microbiological sampling (lower risk) | Annual | HSG274 Pt 2 | Where risk assessment confirms good control and no vulnerable users |
| Hot & cold water - microbiological sampling (higher risk) | Quarterly | HSG274 Pt 2 | Healthcare, vulnerable occupants, complex systems, or history of issues |
| Cooling tower basin - temperature & biocide check | Daily / weekly | HSG274 Pt 1 | Biocide levels checked weekly minimum; temperature and visual daily |
| Cooling tower - microbiological sampling | Monthly | HSG274 Pt 1 | More frequent during commissioning or after incidents |
| Cooling tower - cleaning & disinfection | Twice yearly | HSG274 Pt 1 | At commissioning/recommissioning; at least every 6 months in operation |
| Written risk assessment review | On change or annually | L8 ACoP | Review whenever: system modified; shutdown; positive result; incident. Annual review as default. |
Source: L8 ACoP (HSE UK, 2013), HSG274 Parts 1 and 2 (HSE UK, 2014), applied as the recognised technical standard in Ireland. Compiled by Halpin & Hayward, June 2026.
Legionella Action Levels: What Results Mean
| Result (cfu/L) | System | Status | Required Action |
|---|---|---|---|
| < 100 | Hot & cold water | Satisfactory | No immediate action. Maintain control scheme and monitoring schedule. |
| 100 – 999 | Hot & cold water | Action Level | Review risk assessment. Investigate cause. Increase monitoring frequency. Repeat sampling within 2 weeks. |
| >= 1,000 | Hot & cold water | Immediate Action | Notify duty holder immediately. Investigate urgently. Disinfect system. Confirm remediation with follow-up samples. |
| < 1,000 | Cooling tower | Satisfactory | Continue monitoring programme. |
| 1,000 – 9,999 | Cooling tower | Action Level | Immediate risk assessment review. Increase biocide dosing. Shock dose. Repeat sample within 7 days. |
| >= 10,000 | Cooling tower | Immediate Action | Shut system down. Disinfect. Notify Environmental Health if Legionnaires outbreak suspected. |
Source: L8 ACoP Appendix 3, HSG274 Part 1 Table 2.2, Part 2 Table 2.1. Compiled by Halpin & Hayward, June 2026.
FAQs
A legionella risk assessment in Ireland is a systematic survey and evaluation of all water systems in a premises, carried out to identify the risk of Legionella bacteria growing and being dispersed to people who could breathe in contaminated water droplets. The assessment produces a written document recording the systems surveyed, risk levels identified, control measures in place, and the ongoing monitoring programme required. It must be carried out by a competent person and reviewed regularly.
There is no fixed legal interval for re-assessment, but the risk assessment must be reviewed whenever there is reason to believe it is no longer valid - after building modifications, system changes, positive test results, extended shutdown, or any Legionnaires disease case linked to the building. As a default, an annual review is recommended in L8 and is standard practice in Ireland. The ongoing monitoring programme (temperature checks, water sampling) runs continuously between full risk assessments.
Yes. Under HPSC guidance, all cooling towers and evaporative condensers in Ireland should be registered with the local authority (Environmental Health Officer). The registration requirement exists because cooling towers are the highest-risk water system for Legionella dispersal. Registration allows authorities to identify and inspect cooling towers in the event of a Legionnaires disease cluster in a geographic area.
Legionella Risk Assessment, Testing and Control Ireland