Prioritising Legionella Remedial Actions: Where to Start
Prioritise Legionella remedial actions by the risk each finding creates, not by how easy it is to fix. Deal first with anything that could expose people to contaminated water: a positive result, a system running outside its temperature limits, stagnant or dead-end pipework, or a vulnerable group using the system. Put those ahead of paperwork gaps and cosmetic faults. Give every action one named owner, a due date and clear evidence that it is finished.
This guide is for facilities managers, estate managers, health and safety managers and compliance managers who have a risk assessment with a long list of findings and need to decide what happens this week, this month and this quarter.
TL;DR
HSE guidance expects the risk to be identified and passed to management so that remedial actions can be prioritised. The order is a judgement made by a competent person, not a fixed timetable.
Rank findings by likelihood and severity of exposure: positive samples and temperature failures first, then stagnation and system defects, then records and housekeeping.
If a high-risk fault cannot be fixed straight away, put interim controls in place and record them. Where exposure can be avoided, avoid it.
Each action needs one owner, a deadline and close-out evidence. After a positive sample, close-out means a clear re-test, not just a visit.
Review the risk assessment whenever results, use or the system change.
Table of Contents
What the law and guidance actually say about priority
There is no single rule that says “fix every finding within 30 days”. What the guidance does say is that the risk must be understood and communicated to those in charge. HSG274 Part 1 states that the risk needs to be identified and communicated to management so that they can prioritise remedial actions to control it.
The legal basis sits behind that. A Legionella risk assessment is required under health and safety law, and the dutyholder must appoint a competent person, the responsible person, to manage the control scheme, according to HSG274 Part 1. BS 8580-1 gives guidance on how to carry out those assessments, which are required by the Management of Health and Safety at Work Regulations 1999 and the Control of Substances Hazardous to Health Regulations 2002. If you are unsure who holds this role in your organisation, our guide to the responsible person for Legionella sets out the duties.
In healthcare, HTM 04-01 Part B says that once hazards are identified, the severity of risk needs to be assessed so priorities can be set. The aim is to separate high risks from low ones so attention goes to the risks most likely to cause harm.
In practice that means two things. First, the order of work must be defensible: you should be able to explain why one finding was dealt with immediately and another was scheduled. Second, “low priority” is not “ignored”. Every significant finding needs a place in the plan.
A simple way to rank findings
The approach below is how we suggest organisations structure their action list. It is our working method, built around the guidance above, and your competent person should adapt it to your sites and your risk assessment’s own scoring.
Ask two questions of each finding:
How likely is it that Legionella is growing or being spread? Think temperature, stored water, stagnation, scale, biofilm, aerosol-producing outlets such as showers and spray taps.
How severe would exposure be? Think who uses the water: patients, residents, elderly or immunosuppressed people, children, guests, staff.
Then place the finding in a tier.
Tier | What it covers | Typical response |
1: Act now | Positive or elevated Legionella results; hot or cold water clearly outside control limits at outlets or storage; a system serving vulnerable people with an unresolved fault | Same-day escalation, interim controls, remedial work booked immediately, re-test planned |
2: Act soon | Dead legs and little-used outlets, poorly performing calorifiers or tanks, missing or failed thermostatic mixing valves, uninsulated pipework near heat sources | Scheduled remedial work with a firm date, flushing in the meantime |
3: Plan | Gaps in the written scheme, missing schematics, out-of-date logbooks, training gaps | Assigned tasks within the next planning cycle |
4: Monitor | Minor observations, improvements and future upgrades | Added to the maintenance programme and reviewed at each assessment |
The tiers are a way of ordering work, not a promise that a Tier 3 item is safe to leave indefinitely. A missing written scheme can be the reason a Tier 1 problem went unnoticed.
Findings that belong at the top of the list
Positive or elevated Legionella results
A positive sample is the clearest sign that control has failed somewhere. In healthcare, the PHE guidance on responding to the detection of Legionella sets out a response algorithm with two parts: checking that the trust has assurance in place, and gathering enough information to judge the degree of contamination and the risk to health, then agreeing an appropriate response with the infection control team.
Outside healthcare, the logic is the same. Find out how high the count is, which outlets and which part of the system are affected, who is exposed, and what changed. Our article on Legionella action levels in England explains how thresholds are read and what the audit steps look like.
Temperature failures
Temperature control is the traditional means of controlling Legionella in hot and cold water services. HSG274 Part 2 says cold water should be kept below 20°C where possible, and hot water stored at 60°C at least and distributed so it reaches 50°C (55°C in healthcare premises) within one minute at the outlets. A hot water cylinder running well below 60°C, or a cold tank warm in summer, sits near the top of the list because it affects the whole system rather than one tap. See our breakdown of the HSG274 temperature limits for the detail.
Where temperatures drift repeatedly, spot checks are not enough to see the pattern. Automated water temperature monitoring records continuously, so you can see when a fault started and whether a fix has held.
Stagnation and stored water
Stored water, dead legs and rarely used outlets give bacteria time to grow. A shut-down wing, a seasonal building or a room that is rarely used is a recurring cause. Regular flushing is a quick, low-cost interim control, but pipework that cannot be flushed effectively needs removing or redesigning.
Tanks and system condition
A cold water tank with debris, a damaged lid or poor insulation can compromise everything downstream. Cleaning and disinfection, or repair and replacement where the tank is beyond saving, usually belong in Tier 1 or 2 depending on results and who relies on that supply.
Scalding and Legionella together
Temperature fixes carry their own hazard. HSG274 Part 2 says the risk assessment for higher-risk places such as healthcare premises and care homes should consider both Legionella and scalding. A failed thermostatic mixing valve is therefore a priority item for people who are vulnerable to scalds as well as infection, and servicing should be scheduled with that in mind.
Interim controls when you cannot fix it today
Some fixes need parts, access, a shutdown or a budget decision. The risk does not wait. ACoP L8 says that where the assessment shows a reasonably foreseeable risk of exposure, systems or ways of working that lead to exposure must be avoided so far as is reasonably practicable. Where that is not reasonably practicable, there should be a written scheme to control the risk, properly implemented and managed.
In plain terms, interim measures may include:
taking an affected outlet, shower or area out of use until it is cleared;
flushing and temperature checks at a set frequency;
restoring temperatures at the source, where that is the fault;
a disinfection of the affected section followed by a re-sample;
changing how people use the space, for example restricting showers or spray taps in an affected area.
In healthcare, HTM 04-01 Part B expects the water safety plan to include remedial actions for high counts of P. aeruginosa and Legionella, plus adjustments to clinical practice until remedial actions are shown to be effective.
Write each interim control into the action plan with the date it started, who checks it and what will end it. An interim measure with no end condition quickly becomes the permanent arrangement.
Owners, deadlines and close-out
A ranked list does nothing unless people carry it out. We recommend that every action line has:
One named owner, not a team or a department.
A due date that matches its tier.
Close-out evidence defined in advance: a photograph, a certificate, a temperature log, a lab report.
An escalation route if the date slips, to the responsible person and then to senior management.
ACoP L8 says a suitably experienced and competent person should interpret monitoring and test results, and remedial measures should be carried out promptly when needed. The written scheme should also describe remedial measures if control limits are exceeded, including lines of communication, cleaning and disinfection procedures and emergency procedures.
For anything triggered by a sample, the job is not finished when the engineer leaves. It is finished when a follow-up sample comes back clear. Build the re-test into the original action, with a date.
The PHE guidance notes that most outbreaks occur through incorrect management of water systems, and that a water safety group meeting regularly to review incidents, sampling results and actions is essential for an effective response. Smaller organisations do not need a formal committee, but a short monthly review of open actions, chaired by the responsible person, serves the same purpose.
Testing underpins the whole process. Our Legionella water testing and analysis service starts from £55 per sample, and results can then feed straight into the priority list.
When the order should change
The list is a living document. HSG274 Part 1 says the risk assessment should be reviewed regularly, and specifically when there is reason to think it is no longer valid, for example:
a change to the water system or its use;
a change to the use of the building;
new information about risks or control measures;
check results showing control measures are no longer effective;
changes to key personnel;
a case of Legionnaires’ disease associated with the system.
Any of these can move an item up or down the list. Our guide to reviewing a Legionella risk assessment walks through what a review should cover.
Records that show you prioritised properly
If an inspector, insurer or client asks why something was left, your records are the answer. HSE states that employers with five or more employees must record significant findings and the steps taken to prevent or control risks. Records should cover the people responsible, significant findings, the written control scheme and how it is implemented, the state of operation of the system, and monitoring, inspection, test and check results with dates. Keep them while current and for at least two years afterwards; monitoring and inspection records should be kept for at least five years.
For a remedial action plan this means keeping:
the original finding and the tier you gave it, with the reason;
the owner, due date and any extension, with the reason;
interim controls and the dates they began and ended;
close-out evidence and re-test results;
the date the risk assessment was updated as a result.
The written scheme itself should include, with reference to the risk assessment, an up-to-date system plan, a description of safe operation, the precautions to take, the checks and their frequency, and the remedial action to take if the scheme is shown not to be effective, according to ACoP L8. A logbook that connects findings to actions makes all of this quicker to produce.
Different buildings, different priorities
Healthcare and care settings. HSG274 Part 2 says systems in healthcare premises, care homes and other places where those exposed are likely to be at high risk of infection need particular consideration. HSE’s page on hot and cold water systems adds that in an acute hospital with many susceptible patients, all aspects of the guidance may need to be followed, while in settings with less susceptible residents a local risk assessment helps decide which parts apply. In these buildings a result that might be Tier 2 elsewhere can become Tier 1. See our notes on Legionella risk management for immunocompromised patients and on GP surgeries.
Schools, colleges and universities. Holiday shutdowns are the classic cause of stagnation. Put flushing and temperature checks for the return to term on the plan, and rank outlets in boarding houses, sports changing rooms and science blocks by how long they sit unused.
Hotels and leisure. Rooms that sit empty, showers and spas raise exposure. Guest-facing hygiene sits alongside water safety, and a hotel hygiene checklist for procurement covers the amenity side of that review. For the water side, our hospitality and leisure page sets out how we work with these premises.
Multi-site and office portfolios. Compare findings across sites on the same scale so that budgets follow risk, not whichever site complains loudest. A business premises case study shows how this looks in practice.
Our perspective
In our experience, most organisations do not struggle to find faults. They struggle to decide what to do first, and to show later why they chose that order. We recommend starting from the risk assessment’s significant findings, tiering them by exposure and who is affected, and giving every line an owner and close-out evidence. That is why our assessments are written to be acted on: findings are set out so that a facilities manager can turn them into a plan the same day. Remedial work is rarely one job. A tank clean, a disinfection, a TMV service and a re-sample usually belong together, and sequencing them properly saves repeat visits. Our approach is bespoke to each site, because a dental surgery, a school and a hotel carry different risks even with identical pipework. Our goal is to make compliance simple: clear priorities, documented actions, and ongoing support until the system is back under control. Sammi
How we can help
We carry out Legionella risk assessments from £185, and every finding is set out so you can rank it and act. If your assessment or a test has flagged problems, we can handle the remedial side too: tank cleaning, disinfection and ongoing maintenance, plus TMV servicing and general remedial works. We work with commercial, healthcare, education and housing clients across the UK.
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To discuss a priority list for your sites, get in touch through our main website. If your team needs to understand why the order matters, our Legionella awareness training is available on-site or online.
FAQ
How quickly must Legionella remedial actions be completed?
There is no single statutory deadline for all findings. The duty is to act on the significant findings of your assessment in proportion to the risk, with a competent person deciding the order. High-risk findings such as positive results or failed temperature control should be dealt with immediately, with interim controls if the fix takes longer.
Who decides which remedial actions come first?
The responsible person appointed by the dutyholder, supported by a competent person who can interpret the assessment and results. HSG274 Part 1 says management must be told of the risk so they can prioritise. Many organisations use a risk assessor or consultant to advise on the order.
What if we cannot afford to do everything at once?
Work down the tiers and document the reasoning. Remove or control exposure first through interim measures, then schedule the rest by risk. A recorded, risk-based plan with dates is far easier to defend than an unrecorded list.
When is a Legionella action considered closed?
When the work is done and the evidence shows it worked. For a fault found through a positive sample, that means a clear follow-up sample, not just the engineer’s visit. Record the evidence and update the risk assessment where the system has changed.
Do remedial priorities differ in healthcare?
Yes. Systems serving people at higher risk of infection need particular consideration, and the response to a positive result is agreed with the infection control team in line with PHE and HTM 04-01 guidance. Issues that might wait in an office can be urgent in a ward or care home.
Sources
HSG274 Part 1: Legionnaires’ disease technical guidance (HSE)
HSG274 Part 2: The control of legionella bacteria in hot and cold water systems (HSE)
ACoP L8: The control of legionella bacteria in water systems (HSE)
HTM 04-01 Part B: Safe water in healthcare premises (NHS England)
Responding to the detection of Legionella in healthcare premises (PHE)
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