A cleaning contractor physically cleans and descales the fittings where legionella risk concentrates — shower heads, tank surfaces, cooling-tower packing — while a specialist water-treatment provider handles the chemical dosing, biocide treatment and ongoing monitoring that keeps the whole system under control. Under HSE's ACOP L8, the dutyholder remains responsible for both being done properly, whichever contractors are engaged to do the work.
What ACOP L8 and HSG274 actually cover
ACOP L8 — Legionnaires' disease: The control of legionella bacteria in water systems — is HSE's Approved Code of Practice. It sets out the duties: assessing the risk, appointing a competent "responsible person", establishing a control scheme, and reviewing it. HSG274 is HSE's detailed technical guidance, published in three parts (evaporative cooling systems; hot and cold water systems; and other risk systems such as spa pools) — this is where the practical cleaning and descaling schedules actually live.
What a cleaning contractor typically does
The physical, mechanical side of legionella control sits naturally within a cleaning contract: descaling and cleaning fittings, and physically cleaning tanks and cooling-tower components. HSG274's guidance for hot and cold water systems is specific that shower heads and hoses should be dismantled, cleaned and descaled on a schedule (commonly quarterly, or as set by the risk assessment) — because sediment, scale and biofilm can shield legionella bacteria from temperature and biocide controls that would otherwise be effective. Flushing infrequently used outlets and physically cleaning cold-water storage tanks and calorifiers are the same kind of task.
What a specialist water-treatment provider does
Chemical dosing and biocide treatment, ongoing temperature and disinfectant monitoring, water sampling and legionella culture testing, and the legionella risk assessment itself are specialist, ongoing activities — distinct from a scheduled cleaning visit, and usually carried out by (or for) the appointed competent person. This is a separate discipline from commercial cleaning, and we do not present it as something a general cleaning contract covers.
Who stays responsible either way
HSE's own guidance is direct on this point: you must appoint someone competent "to take responsibility for controlling any identified risk from exposure to legionella bacteria", and even where you engage contractors for water treatment or other work, "it is still the responsibility of the competent person to ensure the treatment is carried out to the required standards". Before appointing any contractor, HSE says you should "be satisfied they can do the work you want to the standard you require" — a decision that stays with you, not the contractor.
How this fits your cleaning contract
We carry out the physical cleaning and descaling elements as part of a wider facilities or cleaning contract, working to your risk assessment and schedule, and alongside your separately appointed water-treatment specialist where one is engaged. We do not carry out chemical dosing or water-system monitoring — that is a distinct, specialist discipline outside our scope, and we would rather say so than blur the line.