Published 23 August 2026 by Prop-Pocket Team
Landlords must understand their legal duties to manage legionella risks in water systems. Learn how to protect your tenants effectively.
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You are the duty holder. If you let residential property, the law treats you as responsible for assessing and controlling legionella risks landlords face through hot and cold water systems, under the Health and Safety at Work Act (HSWA) and COSHH. Most domestic lets do not need a laboratory test certificate; you need a written, proportionate risk assessment instead.
Right now, that means:
Most Legionnaires' cases in England and Wales are sporadic, community-acquired infections rather than outbreaks from communal systems, so the risk in a typical single-let property is low when water moves and temperatures are right.
Landlords are the legal duty holder for legionella risk and must complete a proportionate written risk assessment, without needing a routine test certificate, and back it with temperature checks, flushing, and dated records.
| Point | Details |
| --- | --- |
| No certificate required | A written risk assessment satisfies HSWA and COSHH; lab testing is rarely necessary for domestic systems. |
| Hit the temperature targets | Store hot water at 60°C, deliver 50°C at outlets, and keep cold water below 20°C. |
| Flush before every tenancy | Run all outlets for two minutes after any void, prioritising dead legs and rarely used showers. |
| Review every two years | Reassess sooner if you alter the plumbing, heating system, or occupancy profile. |
| Escalate complex systems | Bring in a competent assessor for HMOs, communal tanks, or properties with a history of problems. |
The legal basis is straightforward even if the acronyms aren't. HSWA places a general duty on anyone controlling premises to manage health risks to occupants, and COSHH extends that to biological hazards, including legionella bacteria. The Health and Safety Executive's ACOP L8 and its accompanying technical guidance, HSG274, set out what "suitable and sufficient" looks like in practice.
Responsibility sits with the landlord as person in control of the premises, even when a letting agent handles day-to-day management. You can delegate the task; you cannot delegate the duty. If your agent forgets to flush a property between tenancies, HSE still holds you accountable.
Certain moments should trigger a fresh look at the risk, not just a calendar reminder:
HSE's position is clear: for a typical domestic hot and cold water system, a landlord who understands the property can carry out the assessment themselves. You don't need a specialist qualification to check a tank lid or run a tap for two minutes with a thermometer in hand.
Bring in a professional when the system gets more complicated:
Pro Tip: If you do hire a contractor, ask for a written report with specific findings, named control measures, and a clear statement of what they assessed. A vague one-page "certificate" with no detail is worth less than the paper it's printed on.
A proportionate assessment follows a logical sequence, not a tick-box form copied from another property.
| Check point | What to look for | Target reading |
| --- | --- | --- |
| Hot water cylinder | Stored temperature | 60°C |
| Hot water outlets | Temperature after running | 50°C or above within one minute |
| Cold water storage | Temperature and tank lid condition | Below 20°C, lid intact |
| Shower heads | Scale, limescale build-up | Descaled, no visible fouling |
Temperature and movement do almost all the work here. Legionella bacteria thrive in stagnant water sitting between roughly 20°C and 45°C, so the goal is simple: keep water either hot enough or cold enough, and keep it moving.
Set these targets and stick to them:
Flushing is your cheapest and most effective tool. Run any outlet that's been idle for more than a week for at least two minutes, and flush every outlet in the property before a new tenant moves in. Dead legs and rarely used taps are among the most common sources of stagnation in rental properties, and both are usually free to fix, just disconnect or cap the unused pipe, or add it to your flushing rota.
Routine maintenance matters more than most landlords assume: keep tank lids intact and screened against debris, descale shower heads on a schedule rather than waiting for visible limescale, and remove pipework that no longer serves a purpose rather than leaving it as a stagnant pocket.
Hands cleaning water tank lid
Pro Tip: Skip the microbiological sampling unless you have a specific reason to suspect contamination. HSE and CDC guidance both treat temperature monitoring and flushing as the primary controls for domestic systems, with lab sampling reserved for outbreak investigation or remediation.
Voids are where legionella risk climbs fastest, because stagnant water is exactly what the bacteria need. A property left empty for a fortnight over Christmas carries a different risk profile to one occupied year-round, and your process should reflect that.
Furnished holiday lets and seasonal properties carry particular risk between bookings, so build the flush into your changeover checklist rather than treating it as an occasional extra.
A record only earns its keep if someone could pick it up in a year's time and understand exactly what was checked and why. Each entry should show the date, the outlet or system component checked, the temperature reading, the action taken, and who did it.
Storing these logs digitally rather than in a paper folder makes the two-year review far easier to evidence if HSE or an environmental health officer ever asks.
Failing to meet your duty under HSWA can lead to prosecution, and a written, dated risk assessment is your strongest defence if a case ever reaches that stage. Records prove you took the risk seriously; their absence suggests you didn't, regardless of the actual state of the plumbing.
A landlord managing multiple properties should also weigh legionella controls alongside other water system health concerns, including issues like damp linked to cavity wall insulation, since both stem from moisture and system maintenance failing at the same time.
Chasing paper logs across several properties is where compliance quietly slips. Prop-Pocket keeps your risk assessments, temperature logs, and service records in one dashboard, so a two-year review or an environmental health query doesn't send you digging through email threads.
Explore the compliance features built for landlords managing legionella checks alongside gas safety, EICR, and EPC records.
Landlords keep asking for a legionella certificate because letting agents and consultants keep selling one, and HSE has had to publicly correct that misconception more than once. The confusion is profitable for whoever's issuing the paperwork, less so for the landlord paying for a lab test their property never needed.
Why the "legionella certificate" myth won't die — overview diagram
What the evidence actually supports is duller and cheaper: check your temperatures, flush your dead legs, write it down, and revisit it every two years. That's the whole job for the overwhelming majority of single-let properties. Where conventional advice falls short is in treating every rental like a hospital plant room, prescribing sampling regimes suited to communal systems onto a two-bed terrace with one shower.
If you take one thing from this, prioritise the write-up over the whizz-bang testing kit. A dated record showing you checked temperatures and flushed the system after a void will do more for you in an HSE enquiry than any certificate a consultant tried to sell you.
— Harv
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