A Legionella risk assessment should be reviewed regularly and whenever system or usage changes affect the risk profile.
Why Review Frequency Matters For Legionella Control
Legionella thrives in water systems that sit in the wrong temperature band and stagnate. A fresh review keeps controls tight and helps your team spot drift in monitoring, training, or contractor tasks before problems pile up. There is no single calendar rule that fits every site, so use a living schedule backed by clear triggers when material change occurs.
How Often Should A Legionella Risk Assessment Be Reviewed: Legal Basics
In the UK, guidance says to review the assessment on a regular basis and when the original findings may no longer be valid (HSE review guidance). Typical triggers include changes to the water system, shifts in use, staff turnover that alters competence, or results that hint at loss of control. Many dutyholders run a brief yearly sense-check and a deeper review every two years. That stance aligns with ACOP L8 and HSG274 language on regular review.
Early Table: Common Review Triggers And Best Next Steps
| Trigger | What It Means | Best Next Step |
|---|---|---|
| New plant, pipework, or layout change | The system no longer matches the last schematic | Update drawings; re-rate risks; set interim monitoring |
| Prolonged shutdown or low use | Stagnation and biofilm growth become more likely | Flush, clean, and re-commission; review controls |
| Temperature or biocide drift | Logs show out-of-limit readings or missed checks | Fix cause; verify; bring forward the assessment |
| Management or contractor change | Competence, roles, and routines may have shifted | Re-brief duties; verify records; test understanding |
| New vulnerable occupants | Higher risk groups now use the building | Tighten limits; raise sampling; review point-of-use |
| Adverse sample or case | Evidence of control loss or suspected link | Initiate investigation plan; revisit the whole assessment |
Baseline Rhythm: A Practical Way To Set Yours
Set two layers: a brief annual review that checks whether controls match the written scheme, and a fuller review every two years that refreshes the risk model, schematics, and control limits. Busy sites, towers, spas, or healthcare rooms often step that up to annual full reviews. Low-risk offices may stretch the deep dive if logs stay tidy and triggers never fire. Document decisions and the reasons for any shortened interval in plain language.
What “Reviewed” Should Actually Deliver
An assessment review is more than a date on a file note. It should confirm that hazards, control points, and limits still match reality, and that people and records show the plan works day to day. A tight review answers five plain questions:
Five Questions That Anchor A Strong Review
- Do the schematics match the plant and outlets that exist today?
- Are control limits clear, measurable, and met in logs and spot checks?
- Are cleaning, flushing, and inspection tasks happening on time?
- Do roles, training, and contractor scopes still fit the system in place?
- Do results, complaints, or incidents point to drift that needs action?
Answer those cleanly, record changes, and update your written scheme. Store evidence with dates, names, and clear outcomes. That trail proves due care and speeds audits.
Who Owns The Timing And The Work
The dutyholder sets the pace and appoints a competent person to lead the assessment. For complex sites, a small water safety team with one owner for sign-off works well.
How To Plan Your Next Review Step By Step
1) Set Scope
List systems in scope: hot and cold water, cooling towers, humidifiers, misters, pools, and any other risk system on site. Confirm which outlets and assets you need to see in person.
2) Gather Evidence
Pull the last assessment, written scheme, schematics, logs, and certificates. Add records of works, shutdowns, and engineering changes since the last review.
3) Walk The System
Verify plant locations, blending valves, dead-legs, and outlets. Check access, labels, and safe sampling points. Note anything that diverges from drawings.
4) Test The Controls
Spot-check temperature at sentinel outlets, verify dosing where used, and look for missed tasks in records. If results look shaky, plan short-term fixes and extra checks.
5) Refresh The Paperwork
Update schematics, re-rate risks, reset limits if needed, and rewrite the task list so it lines up with the plant you have today. Then brief the team and log training.
Linking Your Schedule To Recognised Guidance
UK guidance frames the duty this way: review the risk assessment on a regular basis and when changes mean the old view may no longer hold. That wording leaves room to tailor the interval to the site and risk. In the United States, water management standards place a clear time marker on program reviews. The CDC water management program guidance calls for a review at least once per year and after major changes or control failures.
Mid-Article Table: Review Actions And Evidence To Keep
| Action | What To Record | Proof You Keep |
|---|---|---|
| Annual sense-check | Any drift in limits, tasks, or roles | Signed note, updated task list, training log |
| Full reassessment | New risks, revised schematics, reset limits | Revised report, dated drawings, new scheme |
| Trigger-driven review | Cause, fixes, and new monitoring | Incident record, remedial work orders, retest logs |
| Contractor change | Scope, competence, and KPIs | New contract scope, inductions, competency checks |
| Unplanned event | Water main break, outage, or contamination | Event note, flush plans, post-event results |
Sector Snapshots: Picking A Sensible Interval
The right cadence depends on the setting. Here are working patterns many sites adopt, always with the right to shorten the gap when triggers fire:
Offices And Retail
Where systems are simple and occupancy is stable, many adopt an annual sense-check and a deeper pass every two years. Small sites with spotless logs may hold that line. Sites with showers or long pipe runs often bring the deep pass to yearly.
Hotels And Leisure
Seasonal use and complex pipework push risk up. A full review each year fits many hotels, with a mid-season sense-check. Spas and features that aerosolise water tend to need tight monitoring and quick trigger reviews after any out-of-limit trend.
Healthcare And Care Homes
People on site may be at higher risk. Many adopt annual full reviews and frequent record audits by a water safety group. Point-of-use checks, outlet flushing, and temperature rounds need close daily and weekly attention, with rapid review if results slip.
Building A Review Calendar You Can Stick To
Write the plan into your compliance calendar with owners, dates, and backup contacts. Add reminders for sample kits and access so site walks do not stall. Keep a one-page checklist that lists the next review date, triggers for early revisit, and the named owner.
Quick Wins That Tighten Control Between Reviews
- Put sentinel outlets on one page and mark them in plant rooms and risers.
- Trend temperature and any biocide results, not just single numbers.
- Use short toolbox talks to keep flushing and cleaning on point.
- Log dormant outlets and set weekly purge routines with sign-off.
- After works or outages, add a mini post-event check before reopening.
Common Pitfalls That Derail The Schedule
Three patterns cause most of the pain: letting schematics age while the plant changes, letting records slip into gaps, and setting a fixed date with no trigger rules. Fix those, and your review cadence will hold up under audit and in real-world use.
Bottom Line: A Clear, Defensible Review Rhythm
Set a baseline that fits your site, bake in clear triggers, and pin owners to dates. Review the Legionella risk assessment regularly and whenever change, drift, or evidence of control loss appears. Link your approach to recognised guidance and you have a schedule that sticks.
Authoritative sources worth checking: the UK’s ACOP L8 and HSG274 for dutyholder duties and system checks, and the CDC water management program guidance for a plain outline of program reviews. Use those to sanity-check your calendar and the scope of each review.