Is a shower hose or a fixed head safer for legionella?

Between a flexible hose and a fixed head, the fixed head is the safer default for legionella control, for boring practical reasons: it drains when the water stops, its internal path is short and smooth, and it cannot end up lying in a puddle. A flexible hose retains water along its length after every use, its ridged bore gives scale and biofilm somewhere to grip, and it spends much of its life draped in the warm, wet tray. Neither is safe by default; the shower is the building's aerosol generator, so whichever you have needs a cleaning regime. But the two designs are not equal, and the differences are worth understanding.

Why the shower matters so much in the first place

Legionella reaches people as a fine, respirable aerosol, and the shower is the fixture that makes one on demand, daily, at close range, in an enclosed space. That is why shower heads and hoses get their own lines in monitoring schedules and their own guidance on cleaning and disinfection, and why flushing regimes pay special attention to showers in little-used rooms. The question of hose versus fixed head is about how much harder or easier each design makes that control.

The comparison, property by property

Water retention. When the valve closes, a fixed head and its short arm drain almost completely. A flexible hose only empties if it is hung so it can drain; left looped on the floor of the tray it holds water along its full length, and that water sits at bathroom temperature, in contact with whatever lines the bore, until the next user pushes it out through the spray plate as the first mouthful of spray.

Surface and cleanability. A fixed head's internals are short and accessible: unscrew, descale, disinfect, refit. A hose has a long corrugated bore that traps scale in its ridges and cannot be scrubbed, and its lining degrades with age and kinking. When a hose is heavily scaled, replacement is usually the honest answer, and hoses are cheap enough that this is no hardship.

Backflow. This is the risk few people know about. A hose end resting in a bath or tray holding standing water is a potential siphon: if supply pressure drops while the outlet is open, bath water can be drawn back into the plumbing. It is a recognised backflow scenario, and the fix is physical: restrain the hose so the outlet cannot sit below the spill-over level of the bath or tray, and never leave it lying in standing water.

Replacement economics. A fixed head is a fitting you clean for years. A hose is a consumable: when scale wins or the lining fails, you replace it. Factoring a hose swap into the maintenance cycle is normal practice, not an admission of defeat.

The control regime for either design

Whichever you have, the regime is the same shape. Descale and disinfect the head, and the hose where fitted, at the frequency the risk assessment sets, commonly quarterly: dismantle, descale with a suitable solution, disinfect, rinse, refit. Flush showers in little-used rooms weekly to temperature as part of the outlet regime, and remove the spray head or open the valve gently when flushing so you are not standing in the aerosol. Check hoses hang freely and drain, restrain them out of the tray, and replace them when descaling stops working. Record every clean and every replacement in the log book, because the record is the evidence the control happened.

Temperature still underpins everything. The blended water a shower delivers sits in the growth range by design, which is why the hot side must reach the mixing point hot, why temperature control upstream matters, and why a temperature check at the outlet tells you whether the system behind the shower is doing its job. The scalding side of that balance is covered in scalding versus legionella.

Choosing for a new or refurbished bathroom

If you are specifying rather than maintaining, the decision aid is straightforward. Where a fixed head meets the need, it carries fewer disadvantages: self-draining, cleanable, no backflow posture to manage. Where flexibility is genuinely needed, for assisted bathing, accessibility or cleaning down, choose a hose and manage it properly: a smooth-bore design where available, hung to self-drain, restrained out of the tray, and named in the written scheme of control with its cleaning frequency and replacement triggers. The wrong answer is the one most bathrooms actually get: a hose chosen by default, left looped in the tray, and never on a schedule.