Legionella testing requirements: building a monitoring regime you can evidence

Legionella testing requirements for a business premises are rarely about laboratory samples. They are about a written scheme of control and the routine monitoring that proves it is being followed: temperatures at sentinel outlets, tank inspections, shower head cleans, flushing of low-use outlets. An inspector asking about legionella asks for the log, and the log is what most duty holders cannot produce.

What the scheme of control has to contain

• A schematic of the water system, current enough to be useful — where the tanks, calorifiers, dead legs and sentinel outlets are.
• The control measures chosen, with the parameters written as numbers rather than as "hot" and "cold".
• The monitoring tasks, each with a frequency and a named responsible person.
• The competent person appointed to manage the scheme, and who deputises.
• What to do when a reading is out of range, decided in advance.
• The review interval for the assessment itself.

Legionella testing requirements by frequency: the part that becomes the log

1. Hot and cold temperatures at sentinel outlets — monthly, recorded as measured values.
2. All other outlets on a rolling programme so every one is checked within the year.
3. Calorifier flow and return temperatures monthly, with an annual drain-down inspection where fitted.
4. Cold water storage tank inspection at least annually, more often where conditions suggest it.
5. Shower heads and flexible hoses descaled and disinfected quarterly, or on a justified alternative interval.
6. Low-use and unoccupied outlets flushed weekly, which is the single most-missed task.
7. Thermostatic mixing valve checks and servicing on the manufacturer's interval.
8. Sampling only where the scheme calls for it — stored or recirculating systems, high-risk occupants, or after a control failure.

A reading outside range is not a failure of the scheme; an unrecorded reading is. Write down what you measured, what you did about it, and when it came back into range.

Keep it as a log, not a folder of forms

The monitoring regime produces dozens of small dated entries a month, each attached to a specific outlet or asset. Paper forms in a plant room folder satisfy nobody: they cannot be searched, the gaps are invisible until someone leafs through, and they go missing when the contractor changes. One register with a row per asset and per check — date, value, who, action taken — makes an omission obvious the same week. Ettex Records handles that shape, and where the checks are performed by whoever is on site, Ettex Forms can capture each reading at the point it is taken rather than on a clipboard to be typed up later.

Who does what

The duty holder appoints a competent person; the competent person runs the scheme; a contractor may perform the tasks. None of that transfers the duty. If a water treatment contractor holds all the records, ask for copies as they are produced — when the contract ends, the file you have is the file you kept. This is the same trap as an agent holding certificates in the landlord compliance file.

What an inspection looks for

• A current risk assessment with a review date that has not passed.
• A scheme of control with numeric parameters, not generic advice.
• Monthly temperature records with actual values and no unexplained gaps.
• Evidence that low-use outlets are being flushed, which usually means a weekly record.
• Actions closed out after out-of-range readings.
• Training or competence evidence for the person named in the scheme.

The domestic end of this subject is much lighter: a legionella risk assessment for landlords on a single dwelling needs an assessment and sensible control measures, not a monitoring regime of this weight.