Legionella Prosecutions Up 40%. Two Managers Went to Prison.

Two building managers went to prison last year. Not for negligence. Not for an accident. For deliberately falsifying water temperature records on their legionella management logs. Let that sit with you for a moment. Prison. For paperwork fraud on a water system.

HSE legionella prosecutions were up 40% in 2025. The regulator isn't targeting the buildings with outbreaks — it's targeting the buildings where the documentation doesn't match reality. Because that's where the next outbreak comes from.

Why the HSE Escalated

The COVID pandemic accelerated legionella risk across the UK's commercial building stock. Buildings that sat empty or partially occupied for months had stagnant water systems — perfect breeding conditions. When buildings reopened, many didn't recommission their water systems properly. The HSE's data showed a correlation between buildings that cut corners on water hygiene during COVID and subsequent legionella detections.

What Gets You Prosecuted

The prosecution threshold is lower than most people think. You don't need an outbreak. You need evidence of systemic failure:

• Temperature logs that don't match automated BMS readings (the falsification that sent two managers to prison)
• Missed monthly temperature checks with no documented reason
• Dead legs in the water system that aren't on the risk assessment
• No evidence of L8 training for the responsible person
• A risk assessment that's older than 2 years or doesn't reflect building changes

The Minimum Viable Compliance Programme

Legionella compliance isn't complex. It's consistent. Monthly temperature checks at sentinel points. Quarterly tank inspections. Annual risk assessment reviews. Biennial full risk assessments. Records kept digitally with timestamps that can't be retrospectively altered. That last point is what caught the two managers — they were backdating paper records.

Frequently Asked Questions

How often should legionella risk assessments be reviewed?

Full reassessment every 2 years minimum, with annual reviews of the existing assessment. Any significant change to the water system (new outlets, changed supply, building modifications) triggers an immediate review.

Can automated monitoring replace manual temperature checks?

Automated monitoring complements but doesn't replace manual checks. The HSE expects both — automated systems for continuous monitoring and manual checks to verify the automated readings are accurate.