UKHSA recorded 472 legionellosis cases in England and Wales in 2024, down 22% — with 13 deaths. The key UK Legionnaires' disease statistics for 2026.

Legionnaires' disease is a severe, sometimes fatal pneumonia caused by Legionella bacteria breathed in as a fine water mist — from cooling towers, hot and cold water systems, spa pools and similar sources. This page gathers the current UK figures in one place: how many cases are diagnosed each year, how many people die, which organisms and exposure routes dominate, and what the enforcement picture looks like for the dutyholders who have to manage water systems. The figures are drawn from the UK Health Security Agency's (UKHSA) annual surveillance of legionellosis in residents of England and Wales, Public Health Scotland's (PHS) Scottish surveillance report, and the Health and Safety Executive's (HSE) legionella enforcement and guidance.

Key facts and figures

  • 472 confirmed legionellosis cases were reported in England and Wales in 2024 — a 22.0% fall on 2023.
  • 0.7 per 100,000 was the 2024 incidence in England and Wales, down from 1.0 in 2023.
  • 13 deaths were recorded in 2024, a case-fatality rate of 2.8% (95% CI 1.6–4.9%).
  • 96.5% of confirmed 2024 organisms were Legionella pneumophila (447 of 472 cases).
  • 51.6% of 2024 cases were community-acquired, 43.8% travel-associated and just 4.5% healthcare-associated.
  • 68.0% of 2024 cases were men, and 63.9% were aged 60 or over.
  • 57 cases were confirmed in Scotland in 2024 (10.4 per million) — its highest annual count excluding the 2012 Edinburgh outbreak.
  • £900,000 was the fine imposed on Sanctuary Housing in October 2024 after legionella was found and not properly managed.

Figures are the latest available as of July 2026; this page is updated when new data is released — UKHSA publishes its England and Wales report each autumn (the 2024 report was released on 20 November 2025) and Public Health Scotland publishes its Scottish report each August (the 2024 report on 26 August 2025).

How many cases of Legionnaires' disease are there in the UK each year?

472 confirmed cases of legionellosis were reported among residents of England and Wales in 2024, according to UKHSA — a 22.0% decrease on the 609 cases recorded in 2023. That works out to an incidence of 0.7 per 100,000 population (95% CI 0.7–0.8), down from 1.0 per 100,000 in 2023. In Scotland, Public Health Scotland recorded 57 cases in 2024, so the combined figure for England, Wales and Scotland sits at roughly 530 cases for the year.

Two points are worth keeping in mind when reading any single year. First, most UK Legionnaires' cases are sporadic — isolated infections with no identified common source — rather than large outbreaks, so the annual total moves around with weather, travel patterns and testing as well as with any real change in risk. Second, the England and Wales and Scottish reports are published on separate cycles and use slightly different denominators (cases per 100,000 in England and Wales, per million in Scotland), so the two series should be read side by side rather than simply added without caveat.

Is Legionnaires' disease increasing or decreasing in the UK?

The 2024 fall of 22.0% in England and Wales came straight after a post-pandemic peak: cases had climbed to their highest level of the 2017–2023 series in 2023 before dropping back in 2024. The longer view shows a sharp COVID-era dip and rebound rather than a smooth trend. Cases fell around 38% during the first pandemic year — from 540 in 2019 to 337 in 2020 — as international travel and many workplace water systems went quiet, then recovered strongly as normal activity resumed.

The Scottish series is moving the other way in the short term. PHS recorded 57 cases in 2024, up 7.5% on the 53 cases seen in 2023, describing it as the highest annual number of cases and incidence observed in a year excluding the 2012 Edinburgh outbreak, with no common source or linked exposures identified. In other words, England and Wales came down from a peak in 2024 while Scotland edged up to one — a reminder that a single UK-wide "trend" can hide divergent national pictures.

Year (England & Wales)CasesNotable point
2018553Baseline year in the 2017–2023 series
2019540Last full pre-pandemic year
2020337~38% drop during first COVID year
2023609Highest total in the 2017–2023 series
2024472Down 22.0% on 2023; incidence 0.7 per 100,000

The 2023 total is reported as 604 in UKHSA's 2017–2023 multi-year report and as 609 in the 2024 annual report, which restates the prior year on a slightly updated basis — a normal effect of late case confirmations, and the reason the 22.0% change is calculated against 609.

What is the death rate for Legionnaires' disease in the UK?

The case-fatality rate was 2.8% in England and Wales in 2024 (95% CI 1.6–4.9%), representing 13 deaths among the 472 cases. That is broadly in line with the previous year, when 19 deaths among 604 cases gave a case-fatality rate of 3.1% in 2023. Legionnaires' disease is treatable with prompt antibiotics, but it remains a serious pneumonia — and the death rate climbs steeply where diagnosis is delayed or the patient is older or already unwell.

Scotland's death rate ran markedly higher in 2024: 6 deaths among 57 cases, a case-fatality rate of 10.5%. With case numbers this small, a handful of deaths moves the percentage sharply, so the Scottish and English rates are not directly comparable year-on-year — but the underlying message is consistent, that this is a disease with real mortality rather than a nuisance infection.

The organism matters too. Across the 2017–2023 England and Wales data, infections caused by Legionella longbeachae — a species associated with soil and compost rather than water systems — carried a 28.6% case-fatality rate, against 5.8% for the far more common L. pneumophila. Because L. pneumophila accounts for the overwhelming majority of cases (96.5% in 2024), it drives the headline death toll even though it is individually less lethal than the rarer species.

Which Legionella organisms and sources cause most cases?

Legionella pneumophila caused 96.5% of confirmed 2024 infections in England and Wales — 447 of the 472 cases — with the remaining handful spread across non-pneumophila species. That dominance is why nearly all UK legionella control effort is aimed at the water systems L. pneumophila favours: cooling towers, evaporative condensers, and hot and cold water services running at the wrong temperatures.

By exposure category, 2024 broke down as 239 community-acquired cases (51.6%), 203 travel-associated cases (43.8%) and just 21 healthcare-associated cases (4.5%). Travel-associated infections — picked up from hotel, cruise-ship or holiday-accommodation water systems, often abroad — make up a large and persistent share, which is why UKHSA runs case-cluster surveillance across accommodation sites. Healthcare-associated legionella is the smallest slice at 4.5%; hospital-acquired infection more broadly sits with clinical infection-prevention teams rather than with the water-system dutyholder duties this page is concerned with.

The demographic pattern is stable year to year. In 2024, men accounted for 315 cases (68.0%) and people aged 60 or over for 296 cases (63.9%). Older men remain the group most affected, reflecting both susceptibility and exposure. Regionally, the East Midlands had the highest rate in 2024 at 1.3 per 100,000 (95% CI 1.0–1.6), above the England and Wales average of 0.7.

How many Legionnaires' cases are there in Scotland?

57 cases were confirmed in Scotland in 2024 at a rate of 10.4 per million population, according to Public Health Scotland — a 7.5% rise on the 53 cases (9.7 per million) seen in 2023. PHS records this as the highest annual number of cases and incidence observed in a year, excluding the 2012 Edinburgh outbreak, with no common source or linked exposures identified across the 2024 cases. More than half (56.1%) were travel-associated and the great majority (94.2%) were aged 40 or over.

The 2012 caveat matters: the Edinburgh cooling-tower outbreak that year infected around 90 people and remains the reference point for a large Scottish cluster, so PHS is careful to distinguish a record year of ordinary sporadic activity from a single mass-exposure event. Because Scotland publishes each August and England and Wales each autumn, the two nations' reports are the anchors this page re-checks once a year.

Who is legally responsible for controlling legionella in the workplace?

The dutyholder — typically the employer, or whoever is in control of the premises or the water system — carries the legal duty to manage legionella risk. That duty flows from the Health and Safety at Work etc. Act 1974 and, specifically, the Control of Substances Hazardous to Health Regulations 2002, under which Legionella is a biological agent. HSE's Approved Code of Practice and guidance L8 and the technical guidance series HSG274 set out what "managing the risk" means in practice: a legionella risk assessment, a written scheme of control, someone appointed as responsible, monitoring of water temperatures and treatment, and record-keeping.

Because Legionella is captured by the COSHH Regulations 2002 as a biological agent, the general COSHH framework applies — assess the risk, control exposure, maintain the controls, and train the people involved. A legionella COSHH risk assessment looks different from a chemical one (it turns on water temperature, stagnation, aerosol generation and system design rather than a supplier safety data sheet), but the legal logic is the same. For the wider regime totals — around 13,000 deaths a year linked to past workplace exposures across all hazardous substances — see the COSHH statistics overview; this page covers the legionella slice specifically.

What happens when dutyholders get legionella control wrong?

£900,000 was the fine handed to Sanctuary Housing at Liverpool Crown Court on 22 October 2024, after an HSE investigation found the housing provider had poorly managed the legionella risk in the water system at a sheltered-housing scheme, with staff inadequately trained and supervised. All 44 water samples taken from communal areas and flats tested positive for legionella, and vulnerable residents had to be evacuated while the system was remediated. The company pleaded guilty to breaching Section 3(1) of the Health and Safety at Work etc. Act 1974 and was ordered to pay costs on top of the fine.

A second 2024 case shows what can happen when a system failure is fatal. Amey Community Ltd was fined £600,000 at Lincoln Magistrates' Court on 3 December 2024 following the death of a prisoner, Graham Butterworth, from Legionnaires' disease at HMP Lincoln in December 2017. HSE found the facilities-management contractor had failed to act on a 2016 risk assessment, had no written scheme to control the risk, and had not maintained or monitored water temperatures; samples from the affected cell and nearby showers tested positive for Legionella. Both prosecutions turn on the same failures the L8 regime is designed to prevent — no effective scheme of control, no monitoring, and no competent oversight.

Frequently asked questions

How many cases of Legionnaires' disease are there in the UK each year?

UKHSA recorded 472 confirmed legionellosis cases in England and Wales in 2024 (a 22.0% fall on 2023), and Public Health Scotland recorded 57 in Scotland — roughly 530 across Great Britain for the year. Because most cases are sporadic, the annual total varies with travel, weather and testing as well as with real changes in risk.

Is Legionnaires' disease increasing or decreasing in the UK?

It fell in England and Wales in 2024, down 22.0% after a 2023 post-pandemic peak, but rose 7.5% in Scotland to its highest annual total excluding the 2012 outbreak. Over the longer run, cases dropped sharply during the first COVID year (540 in 2019 to 337 in 2020) and then rebounded.

What is the death rate for Legionnaires' disease in the UK?

The case-fatality rate was 2.8% in England and Wales in 2024 (13 deaths among 472 cases), similar to the 3.1% recorded in 2023. Scotland's 2024 rate was higher at 10.5% (6 deaths among 57 cases), though small case numbers make that figure volatile.

Who is legally responsible for controlling legionella in the workplace?

The dutyholder — usually the employer or the person in control of the premises or water system — under the Health and Safety at Work etc. Act 1974 and the COSHH Regulations 2002. HSE's ACOP L8 and HSG274 guidance require a legionella risk assessment, a written scheme of control, a named responsible person, monitoring and records.

What is the difference between legionellosis and Legionnaires' disease?

Legionellosis is the umbrella term for all infections caused by Legionella bacteria. Legionnaires' disease is the severe pneumonic form and accounts for the great majority of reported cases; the milder, flu-like form is called Pontiac fever. The UK surveillance totals on this page count laboratory-confirmed legionellosis.

Where does Legionella come from in a building?

From engineered water systems that let the bacteria multiply and then generate a breathable aerosol — cooling towers and evaporative condensers, hot and cold water services run at the wrong temperatures, showers, spa pools and similar. L. pneumophila, which caused 96.5% of 2024 cases, thrives in stagnant water between roughly 20°C and 45°C.

Sources & references

Legionella is a COSHH biological agent — make sure the people managing your water systems understand the duty to assess, control and monitor before an inspector or an outbreak does.

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Mark McShane
Mark McShane
Health & Safety Training Specialist, Online CPD Academy

Mark writes about workplace health & safety, COSHH and accredited online training for COSHH Training, part of Online CPD Academy.