The short answer
Yes. Landlords have a legal duty to assess and control the risk of exposure to Legionella for their tenants. That duty comes from the Health and Safety at Work etc. Act 1974, the Control of Substances Hazardous to Health Regulations (COSHH) 2002, and is explained for Legionella by the HSE's Approved Code of Practice L8.
But — and this matters — for most ordinary domestic rented properties, meeting that duty is straightforward and inexpensive. The law requires a proportionate response, not a hospital-grade compliance regime on a two-bed flat.
What the law actually requires
The duty is to identify and assess the risk, and to put in place any necessary controls to manage it. For a typical house or flat with a normal domestic water system, the risk is generally low, and the HSE has been explicit that a simple risk assessment is usually all that's needed.
There is a common myth that landlords must hold a certificate or pay for an annual test. For most domestic lettings that is not the case — there is no legal requirement for a specific certificate, and routine water sampling is not normally necessary. What is required is that a competent assessment has been done and sensible controls are in place.
What a domestic assessment involves
For most rental properties, a Legionella risk assessment is a practical review of the water system: identifying any risk features such as stored water tanks, infrequently-used outlets, showers (which generate aerosol), and any debris or temperature issues. Most modern homes on a mains-fed combi boiler with no stored water are inherently low-risk.
The controls that follow are usually simple and largely common sense: keep hot water hot and cold water cold, flush out infrequently-used taps and showers (particularly between tenancies), keep showerheads clean and free of scale, and advise tenants to do the same. Where there's a cold-water storage tank, keep it covered and in good condition.
When a landlord needs more
The proportionate approach scales up with risk. Larger and more complex properties warrant a more formal programme: houses in multiple occupation (HMOs) with shared and more extensive water systems; purpose-built student accommodation; short-let and holiday-let portfolios where properties sit empty between guests (stagnation is a key Legionella risk); and any property with stored water, communal systems or vulnerable occupants.
In these cases a documented assessment by a competent person, a written scheme of control, and a defined flushing and monitoring regime become appropriate — much closer to the commercial model.
What it costs
For a single domestic property, a competent Legionella risk assessment typically costs in the region of £80–£150 — modest, and valid until something material changes. There's no need to repeat it annually unless the system or occupancy changes; a review every couple of years, or on change of tenancy for higher-risk lets, is sensible.
For HMO and multi-property portfolios, assessments are priced per property and bundled, bringing the per-unit cost down. The key is to pay for a genuine assessment by a competent assessor — not a £20 online template that won't stand up if a tenant ever falls ill.
Getting it right without overpaying
The goal for a landlord is a proportionate, documented, defensible position: a competent assessment, sensible controls actually in place, and a record you can produce if asked. That protects your tenants and protects you.
Avoid both extremes — ignoring the duty entirely, and being scared into an unnecessary annual testing contract on a low-risk flat. A good adviser will tell you honestly which category your property falls into, and most domestic lettings sit firmly in the simple, low-cost one.