The seven-day rule: flushing little-used outlets, and proving it

An outlet that goes unused for seven days or more counts as little-used, and little-used outlets get flushed weekly, or twice a week in healthcare and other higher-risk settings. That is the whole rule, and it is one of the least demanding tasks in the whole HSG274 regime. Run the tap until the water turns over, and move on.

The task is easy. Proving you did it is where firms come unstuck, and it matters more here than almost anywhere else in the programme, because flushing leaves no natural evidence behind. A temperature check produces a number. A flush produces nothing but slightly warmer pipework and an engineer's word that they stood there. If you cannot show it happened, an auditor is entitled to assume it did not.

Why flushing quietly gets skipped

Every other monitoring task on the cadence table writes its own receipt. You take a sentinel temperature and there is a reading to log, a value that either passed or failed. Flushing gives you no such artefact, and that absence does something to how people treat it.

It starts to feel pointless. The outlet was probably fine, the water ran clear, nothing was measured, so the discipline of recording it slips. Over a few months "flushed the little-used outlets" becomes something the round is assumed to include rather than something anyone confirms per outlet. Assumed tasks are the ones that stop happening first, because nothing breaks the day you skip them. The bill for a skipped flush arrives quarterly, in a sample, or years later, in a case.

A tick against "all outlets" is not evidence

If your flushing record is one line a week saying the outlets were flushed, you do not have a flushing record. You have a claim.

Evidence is per outlet. For each little-used outlet, the log should show which outlet it was, who flushed it, the date, and how long they ran it for. That granularity feels like overkill right up to the moment someone challenges it, at which point it is the only thing standing between you and "we can't demonstrate this was done". HSE's guidance expects monitoring records to be authenticated and kept for at least five years, and a flushing log is a monitoring record. Our logbook requirements guide covers what each entry should carry.

The difference is not bureaucratic. "All outlets flushed, week 14" tells a court nothing about the one outlet in the disused wing that actually mattered. A per-outlet line with a name and a time against it is a record of a specific act by a specific person, which is what authentication means.

Flush it properly, not for show

A flush that lasts two seconds is a gesture, not a control. The point is to draw fresh water through the outlet and clear the stagnant volume sitting in the branch, which means running it until the water fully turns over, not until it looks like you have started. On a hot outlet that means running to temperature; on a cold one, running until it runs properly cold. Open it gently rather than blasting it, because a hard spray throws more aerosol, and aerosol is the route legionella takes into the lungs.

None of that is hard, but "for long enough" is the detail that separates a flush from a wave at the tap, and it is exactly the detail a token record cannot capture. "Flushed" with no duration against it does not tell you whether the water turned over or whether someone ran the tap while checking their phone.

First you have to find them

You cannot flush what you have not identified, and little-used outlets are routinely the ones a programme overlooks, precisely because they are out of the way. They hide in the parts of a building nobody visits:

• Voids and plant spaces with a tap nobody remembers.
• Disabled WCs that see a fraction of normal use.
• Cleaners' sinks and janitorial cupboards.
• Showers in converted offices, where nobody actually showers.
• Guest rooms, spare consulting rooms, or any space used only occasionally by design.

Any outlet that goes seven days without use belongs on the flushing schedule, and the list is not static. A team moves floor and a bank of kitchen taps goes quiet. A meeting room is taken out of use. The little-used list has to be revisited as occupancy shifts, or it goes stale in exactly the way the outlets do.

Who actually does the flushing

Weekly flushing is usually not the visiting water-hygiene engineer's job. It is too frequent for a monthly or quarterly contract, so it lands on whoever is on site every day: a caretaker or a facilities assistant. That is sensible, and it is also where the evidence problem sharpens. The person flushing is often not the person who understands why, and the little-used list lives in the engineer's head or the risk assessment rather than in the caretaker's hands.

If flushing is delegated, the list of what to flush and the place to record each one have to be delegated with it, in a form a non-specialist can follow without a training course. A weekly task handed over with no list and no log is a weekly task that becomes a monthly one, then an assumed one. Twice-weekly flushing in a care home or hospital raises the stakes on the same handover, because the interval leaves even less room for a dropped round.

Stagnation is worse after a shutdown

The seven-day threshold is about ordinary weeks. After a longer closure the risk is larger, because water that has sat in pipework for weeks has had time in the 20–45°C growth band that flushing exists to prevent. A building coming back from a seasonal closure or a mothballed period needs more than its normal weekly flush before those outlets are safe to use — a task in its own right, and we covered bringing a water system back into use separately.

The point that ties the two together is the same. An outlet with no flow is an outlet growing something, whether it went quiet for eight days or eight weeks.

This specific failure has a price tag on record. When BUPA Care Homes was fined £3,000,000 following the Legionnaires' death of an 86-year-old resident, one of the findings against the company was that there had been no proper system for flushing at all. Not a flushing programme done badly. No system for it. The least glamorous task in the regime was central to a three-million-pound case.

This is the kind of round BlueWave is built to carry. A weekly flush becomes a recurring job against the actual little-used outlets on a site, and the engineer records each one in the field app with a timestamp and their name attached, with or without signal, so the evidence is per outlet by default instead of one hopeful line a week. A missed round shows as overdue rather than dissolving into an assumption.

If you want to know whether your flushing would survive scrutiny, pick one little-used outlet and one week from last year, and try to name who flushed it and for how long. If the honest answer is "it would have been on the round", you have a claim, not a record, and that is the gap the seven-day rule keeps falling into.