A showerhead does the two things Legionella needs, in one fitting: it holds a little warm water still between uses, then breaks it into a fine, breathable spray the second someone steps in [4]. Scale and slime build up inside the rose and the hose, give the bacteria somewhere to shelter, and the next person inhales whatever has been growing in there. Cleaning and descaling takes that shelter away. The schedule is how you keep it gone.

This is a job a competent site team can do in-house with a bucket, gloves and a descaler. Below is the procedure, then a way to decide how often to repeat it for each shower instead of putting the whole estate on one blanket date.

Before you start

Three things should be in place before the first head comes off:

  • A current risk assessment that lists your showers and flags the low-use and higher-risk ones — care settings, gyms, sports pavilions, rarely-let rooms. The interval you settle on should trace back to it [1].
  • The right kit: nitrile gloves, eye protection, a descaling solution suitable for the fitting, a soft brush, a bucket, and somewhere to run the rinse to waste.
  • A logbook entry ready to fill in. An undocumented clean is, for audit purposes, a clean that never happened.

Pick a time when the shower is out of service and tell whoever uses it. Aerosol exposure during the strip-down is a genuine consideration, so don’t do this with people in the room.

The procedure, step by step

1. Isolate and protect. Turn the shower off and, where you can, isolate the supply. Gloves and eye protection on before you touch anything. Why: dismantling a scaled head can release spray and loosen contaminated debris. Done when: the outlet is dead and you are kitted up.

2. Remove the head and the hose. Unscrew the showerhead, and on flexible showers take the hose off too. Hoses get skipped constantly and are often worse than the head — the ribbed inner bore is ideal ground for biofilm. Why: you cannot descale what you cannot reach, and the worst scale sits on internal surfaces you never see from the outside. Done when: head and hose are both off and you can see daylight through each.

3. Strip the scale. Soak the head and hose in descaler per the product instructions, then brush out the loosened deposit. Clear every spray hole. Why: scale is both the home for biofilm and the reason flow drops and the spray pattern goes ragged. Done when: the holes run clear and no chalky deposit remains.

4. Disinfect, then rinse. After descaling, disinfect the components as your written scheme specifies, then rinse thoroughly to waste. Why: descaling removes the habitat; disinfection deals with what is living in it. They are two different steps, not one. Done when: the parts are rinsed and free of chemical residue.

5. Refit and run. Reassemble, then run the shower to full temperature for long enough to clear the line, directing the spray to keep aerosol down. Why: refitting disturbs the fitting, and the run proves you have not introduced a leak or a blockage. Done when: hot runs hot, cold runs cold, and the spray pattern is even.

6. Record it. Log the date, the outlet reference, what you found (heavy scale, discolouration, damage), what you did, and the next due date. Why: the record is what proves control to an auditor and what tells you whether the interval is right. Done when: the entry is complete and the next date is set.

The two steps people skip are the hose and the disinfection rinse. A head that sparkles on a furred hose is a half-finished job.

Setting the cycle for each shower

A blanket “every shower, every quarter” is easy to schedule and often wrong in both directions — too frequent for a busy outlet, not nearly enough for a problem one. HSG274 points to a quarterly clean-and-descale as a common starting point for showerheads and hoses [2], but the interval should move with the evidence. Work down this path for each shower:

  • Is it in a higher-risk setting or used by vulnerable people — healthcare, a care home, assisted living? Then hold it at the baseline interval at least, and treat any slippage as urgent rather than routine.
  • Is it a low-use or intermittently-used outlet — a void room, a spare changing block, a seldom-booked facility? Then it needs flushing between cleans, and stagnation, not scale alone, is the thing driving the risk (see flushing little-used outlets).
  • Is the supply hard water, or did the last clean turn up heavy scale? Then shorten the interval. Scale that comes back fast is telling you the cycle is too long.
  • Was the last clean light, the outlet in daily use, temperatures consistently in range? Then you may be able to stretch the interval — with the risk assessment’s sign-off and the records to back the decision.
  • Has anything changed — a refurb, an occupancy shift, a temperature failure, a complaint about debris? Then bring the clean forward and review the interval.

The schedule is an output of evidence, not a fixed calendar entry. Two showers in the same building can legitimately sit on different cycles, and a good logbook makes that defensible rather than arbitrary.

Checking it actually worked

The proof of a clean is in the next few records, not the day itself. Watch for scale returning quickly, flow dropping off again, or temperatures drifting at that outlet — each is a sign the interval, or the wider control regime, needs another look. Where the risk assessment calls for it, sampling can verify microbiological control [3], but remember which is which: the clean is a control measure and the sample is only evidence. A negative result never excuses a head you can see is furred.

A note on the limits of this

The intervals and steps here are a starting framework, not a rule that overrides your own assessment. The right cycle, the right descaler and the right disinfection method depend on the fitting, the water, the people exposed and the rest of the control scheme — all of which a competent person should weigh up on site. Treat the manufacturer’s instructions for both the descaler and the fitting as binding, and let your risk assessment, not this page, set the final numbers.

FAQ

Should I descale and disinfect, or is one of them enough?

Both, in that order. Descaling strips out the scale that shelters bacteria and restores the flow; disinfection then deals with the biofilm and organisms living in it. Skip the descale and you leave the habitat; skip the disinfection and you leave the occupants.

Do hoses really need the same attention as the head?

Yes, and often more. The ridged inner wall of a flexible hose is a favourite spot for biofilm, it rarely gets inspected, and a spotless head on a fouled hose is only half the task. Clean or replace hoses on the same cycle as the head.

Can I just replace cheap showerheads instead of cleaning them?

Sometimes that is the sensible call — a damaged or badly scaled head can cost less to swap than to recover, and some sites standardise on easy-clean or replaceable heads for exactly that reason. A replacement still needs recording, though, and a new head on an old hose is not a fresh start.

Sources

[1] HSE, “Legionnaires’ disease. The control of legionella bacteria in water systems - Approved Code of Practice and guidance (L8)”. https://www.hse.gov.uk/pubns/books/l8.htm [2] HSE, “Legionnaires’ disease: Technical guidance (HSG274)”. https://www.hse.gov.uk/pubns/books/hsg274.htm [3] HSE, “Testing and monitoring your water system for legionella”. https://www.hse.gov.uk/legionnaires/testing-monitoring-water-system.htm [4] CDC, “How Legionella Spreads”. https://www.cdc.gov/legionella/causes/index.html