What are the weekly legionella checks?
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Key points
- The weekly round is flushing little-used outlets to temperature: hot settling at ≥50°C, cold at <20°C.
- Work nearest the supply first, outward, so each branch is purged in order.
- Open spray fittings gently, or remove the head, because flushing itself creates aerosol.
- Budget roughly twenty to forty minutes for a small premises, plus recording as you go.
- An outlet that repeatedly will not reach temperature is a fault to escalate, not a flush to repeat forever.
The weekly legionella check is a short, fixed routine: take the list of little-used outlets from your risk assessment, flush each one gently until the temperature stabilises at the right figure, and write down the date, outlet, temperature and your initials as you go. For a small premises with half a dozen outlets the whole round takes twenty to forty minutes. Here is that round, minute by minute, exactly as a caretaker or site manager would run it.
Before you start: minutes 0 to 3
Three things in hand before the first tap opens. The little-used outlet list from the written scheme of control, with every outlet named properly. A clean probe thermometer. And the flushing log, whether that is the paper sheet on a clipboard or the log book open on your phone. If your scheme adds weekly extras, a glance at the calorifier thermometer or a look at the tank lid, do them first so the round ends at the outlets.
Plan the route: nearest to the supply first
Order matters. Start at the outlet nearest the incoming supply or the plant and work outward to the most distant. Each branch is then purged in sequence, and you are never pushing standing water from a far branch back past an outlet you have already flushed. On a two-loop system, run the hot loop then the cold, or the reverse; the point is one complete pass with no doubling back. Flushing little-used outlets explains the turnover principle behind the route.
At each outlet: minutes 3 to 30
Each outlet follows the same four steps:
- Open gently. A quarter to half open is enough. On a shower or spray tap, remove the head or hose first where practical and run the water as a stream, because flushing a colonised branch is itself a release of aerosol. Open a window or run the extractor if the room has one.
- Run to temperature, not to the clock. Probe in the flow, watch the reading climb or fall. Hot outlets run until they settle at 50°C or above (55°C in healthcare); cold outlets until they drop below 20°C. A tap near the plant may take thirty seconds; a distant shower on a long branch may take several minutes. The stabilised temperature is the signal that fresh water has arrived, which is why a fixed guessed time cannot be right for every outlet. The temperature chart has the targets; the temperature checker settles any borderline reading on the spot.
- Look at the water. Discolouration, debris or an odd smell are worth a note even when the temperature passes.
- Record immediately. Date, outlet name, stabilised temperature, initials, straight into the log before you walk to the next outlet. Recording at the end of the round from memory is where rounds quietly stop being evidence.
Six outlets at two to five minutes each, with walking between them, lands the round in the twenty-to-forty-minute range for a typical small building.
The weekly round is short, fixed and honest: flush every little-used outlet to temperature, write it down at the outlet, and escalate anything that will not comply. Twenty minutes a week is what keeps the stagnation clock from ever reaching seven days.
Free legionella risk assessment template
A structured Word document following the five-step approach in ACOP L8. Covers risk identification, written scheme, monitoring, and records. If it isn't written down, you can't evidence it.
Follows ACoP L8 and HSG274 Part 2. Free. No spam.
When an outlet fails the weekly check
A hot outlet that will not reach 50°C, or a cold one that will not drop below 20°C, has told you something the flush cannot fix. Note it, report it to the responsible person, and record the escalation. Common causes are a scaled or failed thermostatic mixing valve on that branch (see TMV servicing), a circulation problem, or a branch that has effectively become a dead leg and should be cut back or removed. An outlet that fails week after week is not a flushing problem; it is a system fault, and the log should show it being treated as one.
Keeping the weekly round alive
The weekly check dies by routine drift: the same person away for two weeks, a new room quietly becoming little-used, the log filled in on Friday for the whole week. Three habits keep it alive. The flush list is reviewed whenever room use changes. A named deputy holds the list and the thermometer. And the record is checked monthly by the responsible person, not just filed, because a week with no entry should trigger a question, not silence. The weekly round feeds the wider regime described in how you monitor legionella, and its records sit alongside the monthly and annual checks in the monitoring log sheets. Like every record on this site, the weekly log is a recording tool: it evidences the control, it never certifies the water safe.
Free legionella risk assessment template
A structured Word document following the five-step approach in ACOP L8. Covers risk identification, written scheme, monitoring, and records. If it isn't written down, you can't evidence it.
Follows ACoP L8 and HSG274 Part 2. Free. No spam.
Frequently asked questions
What are the weekly legionella checks?
The core weekly check is flushing little-used outlets: every tap, shower or fitting used less than about once a week is run gently until fresh water arrives and the temperature stabilises, hot at 50°C or above, cold below 20°C. Each flush is recorded with the date, outlet, temperature and initials. Some written schemes add small weekly items, such as a stored-temperature check at the calorifier or a look at the tank, but flushing is the universal weekly task.
How long does the weekly legionella flush take?
For a small premises with half a dozen little-used outlets, expect roughly twenty to forty minutes including recording. Each outlet takes as long as it takes the temperature to stabilise: a tap near the plant may settle in thirty seconds, a distant shower on a long branch may need several minutes. Flushing to temperature rather than to the clock is the correct method, so the round takes as long as the building demands.
Should you remove shower heads before flushing?
Where practical, yes, or at least open the outlet gently so the flow does not atomise. Flushing deliberately runs water through a branch that may be colonised, so it is itself a release of aerosol. Removing the spray head or hose and running the water as a stream, then cleaning and refitting the head, limits the spray. Opening a window or running an extractor while you flush is a sensible extra precaution.
What do you record after a weekly flush?
Record the date, the outlet by its proper name, the temperature reached at the end of the flush, and your initials, plus anything unusual such as discoloured water or an outlet that would not reach temperature. The record goes straight into the log book at the time of the flush. An outlet that repeatedly fails to reach temperature should be escalated to the responsible person rather than flushed and forgotten week after week.
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