Respond: what now?

A water sample has returned a Legionella count above your action level.

1. 1

   Confirm the result and the action level

   Check the count against the HSG274 bands and your scheme; a single low positive is handled differently from a high one. Read more ›

2. 2

   Tell your Responsible Person and competent help

   Decisions on disinfection and re-sampling are for a competent person, do not act alone if unsure. Read more ›

3. 3

   Review controls and act

   Look at temperatures, stagnation and the affected outlets; consider control measures or disinfection as advised. Read more ›

4. 4

   Re-sample and record

   Re-sample after action to confirm recovery, and record the result, decision and reasoning in your logbook.

Do not assume one clear sample later proves the system safe, and do not skip recording the decision, the record is the evidence.

Someone who used your building has, or may have, Legionnaires’ disease, or public health has been in touch.

1. 1

   Cooperate fully with public health

   UKHSA / your health-protection team lead the investigation; give them your risk assessment, records and system information promptly. Read more ›

2. 2

   Check whether RIDDOR applies

   Some work-linked cases are reportable to the HSE under RIDDOR, check the criteria. Read more ›

3. 3

   Preserve evidence and do not disturb the system

   Do not flush, disinfect or alter the system before sampling unless instructed, it can destroy the evidence of the source.

4. 4

   Pull your records together

   Recent temperatures, monitoring, any positive samples and the risk assessment will all be asked for.

Do not brief staff or the public with speculation, and do not disinfect to "be safe" before investigators have sampled.

A hot outlet is too cool, or a cold outlet too warm, at a monitoring check.

1. 1

   Re-check and confirm

   Confirm the reading and how long the outlet was run; a brief low reading at a rarely used tap differs from a system-wide drift. Read more ›

2. 2

   Find the cause

   Calorifier temperature, a failed TMV, a long dead leg, or cold water warming near a heat source are common causes. Read more ›

3. 3

   Correct and re-check

   Fix the cause, flush if needed, and re-measure to confirm the outlet returns to target.

4. 4

   Record the fault and action

   Log the out-of-range reading, the cause and the corrective action, patterns matter at review.

Do not just tick "out of range" and move on; an untracked drift is exactly what enforcement looks for.

An inspector has contacted you, visited, or issued a notice.

1. 1

   Find your risk assessment and records

   A current risk assessment, written scheme and recent monitoring records are the first things asked for. Read more ›

2. 2

   Understand what was issued

   Advice, an improvement notice (fix by a date) and a prohibition notice (stop using the system) are very different. Read more ›

3. 3

   Act within the timescale

   Address the findings by the date set, keep evidence of what you did, and ask if anything is unclear.

4. 4

   Close the loop with records

   Document the remedial work and keep it, demonstrating control after the fact still matters.

Do not ignore a notice or let the deadline pass; that escalates a fixable problem into prosecution.

A cooling-tower dip slide, biocide or Legionella result is out of control, or you have a new/idle tower.

1. 1

   Act on the contractor’s result yourself

   The legal duty stays with you, not the water-treatment contractor, read the visit sheet and respond to out-of-control readings. Read more ›

2. 2

   Clean, disinfect and restart safely

   A tower that has been idle or out of control needs cleaning and disinfection before it returns to service.

3. 3

   Confirm notification to the local authority

   Notifiable cooling towers must be registered with the local authority (and de-registered when removed).

4. 4

   Record and review the scheme

   Log the loss of control and the response, and check the control scheme parameters and frequencies still fit.

Do not assume the contractor "has it covered", accountability for acting on results is yours.