If you let a home in England, Wales or Scotland, you have a legal duty to assess and control the risk of legionella in its water system. That duty doesn't come from a special landlord law. It comes from the same health and safety law that applies to employers. The Health and Safety Executive (HSE) treats a residential landlord as someone who controls premises that other people live in.
Most landlords can do the assessment themselves. There's no such thing as a legal "legionella certificate", and testing the water usually isn't needed. Plenty of landlords still get this wrong, either by ignoring it or by paying for something they don't need. This guide covers what the law actually says and how to do a sensible assessment. It also covers what to record and where your landlord insurance comes in if a tenant falls ill.
If you already have landlord insurance, send us your current policy or renewal. We'll check the liability section and its conditions and look for a better quote from the insurers on our panel. Start with a landlord quote review.
The short answer
Do landlords need a legionella risk assessment? Yes. Landlords must assess the risk from legionella in the water systems of the homes they let and put proportionate controls in place. HSE guidance is clear on this.
Where does the duty come from? The Health and Safety at Work etc. Act 1974 (HSWA) and the Control of Substances Hazardous to Health Regulations 2002 (COSHH). Legionella bacteria count as a biological agent under COSHH.
Can I do it myself? Usually, yes. HSE says most landlords can assess the risk themselves. You only need outside help if you're not confident or the system is complex.
Do I need a legionella certificate or a water test? No. There's no legal "legionella test certificate", and HSE says testing (sampling) isn't usually required for domestic lets.
How often? The law sets no fixed interval. Review the assessment periodically and whenever something changes, such as a new boiler, new tenants or a long void.
Do I have to write it down? The legal duty to record findings only applies to employers with five or more employees. Keep a short written record anyway. It's your evidence if something goes wrong.
Where insurance fits: if a tenant or visitor says they caught Legionnaires' disease from your property, the liability section of your landlord policy (property owners' liability) is the part that may respond. Fines from a prosecution aren't insurable.
What legionella is, and why landlords are involved
Legionella bacteria live naturally in water. They become a problem when they multiply in man-made water systems and people breathe in tiny droplets (aerosols) of contaminated water, for example from a shower. The illness they cause, Legionnaires' disease, is a potentially fatal form of pneumonia. Older people, smokers and people with weakened immune systems are most at risk.
The bacteria grow best in water between about 20°C and 45°C. They grow where water sits still and where there's scale, sludge or biofilm for them to feed on. That's why the controls below focus on three things: keeping hot water hot, keeping cold water cold, and keeping water moving.
The risk in a typical modern flat is usually low. A small amount of thought and a few simple controls deal with it. The risk goes up with stored hot water cylinders, cold water tanks in the loft, long or redundant pipe runs, showers that aren't used, and homes left empty for weeks.
What the law says
There are three pieces of legislation and two pieces of HSE guidance you'll see mentioned. Here's what each one does.
Source | What it does for landlords |
|---|---|
Health and Safety at Work etc. Act 1974, section 3 | Section 3(2) puts a duty on self-employed people to conduct their undertaking so that others aren't exposed to risks to their health and safety. |
HSWA section 53 | Defines "self-employed". HSE's position is that a landlord who rents out a property is treated as self-employed for this purpose, so section 3 applies. |
COSHH Regulations 2002 | Requires risks from hazardous substances, including biological agents such as legionella, to be assessed and controlled. |
Approved Code of Practice L8 (4th edition, 2013) | HSE's code "Legionnaires' disease: The control of legionella bacteria in water systems". It explains how to comply with the law. |
HSG274 | HSE's technical guidance that sits alongside L8, including Part 2 on hot and cold water systems. |
Who counts as a landlord?
HSE's guidance uses a wide definition. You're a landlord for these purposes if you rent out a home under a lease or licence of less than seven years. That includes renting a room in your own home. So the duty covers:
single buy-to-let houses and flats
HMOs and shared houses
holiday and short lets, where you control the water system
letting agents and managing agents who take on the landlord's maintenance duties under the management contract
lodger arrangements in your own home
If a managing agent looks after the property for you, the agreement should say clearly who's responsible for the legionella assessment and controls. If it doesn't, assume it's still you.
Scotland and Northern Ireland
HSWA and COSHH apply across Great Britain, so the same duty applies to landlords in Scotland. Scottish private landlords also have the Repairing Standard and Scottish Government guidance to consider. Our landlord insurance in Scotland guide covers the Scottish side. Northern Ireland has its own equivalent health and safety legislation, enforced by HSENI.
Do you need a legionella certificate?
No. This is one of the most common misunderstandings in letting. Unlike gas safety, there's no annual certificate, no prescribed form and no "pass". HSE says plainly that the law doesn't require a legionella test certificate.
What you need is a risk assessment that's proportionate to the property and the controls that come out of it. Some agents and contractors sell "legionella certificates" or routine water sampling for ordinary homes. Sampling has its place in larger or higher-risk systems. For a typical rented house or flat, HSE says it isn't usually needed. A sensible written assessment that you act on is better evidence than a lab result from one day.
Our landlord safety certificates checklist sets out which checks really do need a certificate (gas, electrical and EPC) and which, like legionella, need an assessment instead.
How to do a landlord legionella risk assessment
HSE says a simple assessment is enough for most homes. The point is to understand the water system, spot where water could sit warm and still, and decide what to do about it. Here's a practical way to work through it.
Step 1: Map the water system
Walk round the property and note:
How hot water is made. A combi boiler or electric showers heat water as it's used and store little or none. A hot water cylinder (calorifier) stores it.
How cold water arrives. Is it straight from the mains, or is there a cold water storage tank, usually in the loft?
Outlets. Every tap, shower, bath and outside tap. Note any that are rarely used, such as a second shower or a utility room tap.
Dead legs and redundant pipework. Pipes that lead to nothing, or to an appliance that's been removed. Water sits still in them.
Other sources of spray. Spa baths, hot tubs, garden hoses and anything else that creates a fine spray.
Step 2: Identify where the risk is
The question for each part of the system is whether water could sit between 20°C and 45°C, stay still, or pick up dirt and scale. Typical risk points in rented homes are:
a hot water cylinder set too low
a loft tank with a loose lid, no insulation or debris inside
showers and taps that aren't used for a week or more
long pipe runs that let hot water cool or cold water warm up
the property sitting empty between tenancies
a hot tub or spa bath provided with the let
Step 3: Consider who lives there
Think about the tenants. Higher-risk groups include people over 45, smokers, heavy drinkers and people with chronic respiratory or kidney disease, diabetes or weakened immune systems. You don't need medical details. But if you know you're letting to an elderly tenant or a supported-housing provider, take that into account.
Step 4: Decide on controls
HSE gives an example of a low-risk home: cold water direct from the mains, and hot water from instantaneous or small low-volume heaters at a temperature of about 50°C. If that describes your property and there's nowhere for water to stagnate, your controls may be little more than keeping things as they are and telling tenants what to do.
Where there's stored water or other risk factors, the usual controls are:
Hot water storage at 60°C or more. Set stored hot water cylinders to 60°C. Fit thermostatic mixing valves where there's a scalding risk, for example for elderly or vulnerable tenants.
Cold water kept cold. Insulate pipes and tanks so cold water stays below 20°C.
Tight-fitting tank lids. Cold water tanks should have a lid that fits properly, to keep out debris and vermin.
Remove dead legs. Take out redundant pipework when you can, for example during a refurbishment.
Flush before a tenancy. Run all taps and showers before new tenants move in, especially after a void.
Simplify where possible. Replacing an old cylinder and tank system with a combi boiler, or fitting electric showers, reduces the risk.
Step 5: Check the temperatures
HSE's "things to consider" for hot and cold systems give simple checks that you, or your gas engineer, can do with a thermometer:
Check | What you're looking for |
|---|---|
Cold water outlet, after running for 2 minutes | Below 20°C |
Hot water outlet, within 1 minute of running | At least 50°C |
Hot water leaving the cylinder (calorifier) | At least 60°C |
If the readings are off, find out why. A cylinder thermostat may need adjusting, or a tank may be sitting in a hot loft.
Step 6: Tell your tenants what to do
Tenants should be told about the controls that rely on them. HSE suggests telling them:
not to adjust the hot water cylinder's temperature setting
to clean and descale showerheads regularly
to let you know if the hot water isn't heating properly or the system isn't working as it should
to run taps and showers that they don't use often, and to flush them after they've been away
A short section in your welcome pack or tenancy information is enough.
Step 7: Write it down and set a review date
Write down what you found, what you've done and what the tenants have been told. A page or two is fine for a typical home. Include photos of the tank and cylinder settings if that helps. Then decide when you'll look at it again.
How often should a legionella risk assessment be reviewed?
The law doesn't set an interval. HSE's guidance is to review the assessment regularly and whenever there's reason to think it's no longer valid. Good triggers for a review are:
a change of tenant
changes to the water system, such as a new boiler, cylinder or bathroom
the property standing empty for a long period
a tenant becoming more vulnerable, or a new occupant at higher risk
a complaint about hot water or a tenant reporting illness
Many landlords pair it with the annual gas safety check. HSE notes that checks can be carried out during other routine visits, such as gas safety inspections. Our guide to the landlord gas safety certificate and insurance covers that visit.
Empty properties and voids
Voids are the highest-risk time in an ordinary let. Water sits still in pipes, tanks and cylinders for weeks. HSE's guidance for vacant properties is:
if the property will be empty for a while, run all outlets at least once a week to keep water moving
if that isn't practical, consider draining the system down
before the new tenant moves in, flush the system through, running hot and cold outlets
Voids matter for insurance too. Most landlord policies have an unoccupancy clause. After a set number of consecutive days empty, cover may be restricted or conditions apply, such as regular inspections or draining down the water system in winter. Check what yours says before a long void. Running taps for legionella control and inspecting for the policy can be done on the same visit.
HMOs, blocks and higher-risk lets
The same principles apply to every let, but some properties need more than a simple self-assessment.
HMOs and shared houses. Usually bigger systems, more outlets and more chance that showers in empty rooms go unused. Rooms can be empty between lets while the rest of the house is occupied.
Blocks of flats. Where there's a shared tank or central hot water system, the freeholder or managing agent controls it, and the duty for the shared system sits with them. Leaseholders who let their flat are still responsible for the water system inside it. Our guides to block of flats insurance and landlord insurance for a leasehold flat cover how responsibilities split.
Holiday lets and serviced lets. High turnover and gaps between bookings mean more stagnant water. Hot tubs and spa baths need their own controls under HSE guidance.
Supported or older people's housing. Occupants are more at risk, so the assessment and controls should be more thorough.
For these, it's often worth paying a competent person to carry out or review the assessment. Choose someone who can explain their findings and who doesn't automatically recommend sampling or treatment you don't need.
What happens if you don't do it?
HSE doesn't routinely inspect rented homes for legionella. That isn't the same as there being no consequences. The main risks are:
Prosecution. HSE's landlord guidance says that if a tenant contracts Legionnaires' disease from the water system, the landlord could be prosecuted under HSWA. Having no risk assessment, or one you didn't act on, makes that much harder to defend.
A civil claim. A tenant or visitor who becomes ill can claim compensation for injury, loss of earnings and other losses if they can show you were negligent.
Local authority action. Councils can take action on hazards in rented homes under their housing powers. Problems with hot water supply, water storage or hygiene can come up in a housing inspection.
Letting agent and lender problems. Many agents and lenders ask for confirmation that the assessment has been done.
Where landlord insurance fits
Insurance doesn't replace the risk assessment, but it's part of the picture if something goes wrong. Here's how the main parts of a typical landlord policy relate to legionella.
Situation | Part of the policy that may respond | Points to check |
|---|---|---|
A tenant or visitor claims compensation after contracting Legionnaires' disease | Property owners' liability (landlord liability) | The limit of indemnity, how legal costs are treated, and any conditions or exclusions relating to legionella or water systems |
You're investigated or prosecuted under health and safety law | A legal defence costs extension to the liability section, or landlord legal expenses cover, where included | Whether health and safety prosecution defence is included at all, and on what terms. Fines and penalties themselves aren't insurable. |
The water system needs work after a problem is found | Usually not covered. Maintenance and upgrades are your cost | Buildings cover responds to sudden damage, such as an escape of water, not to the cost of bringing a system up to standard |
The property is empty and pipes are left full | Unoccupancy conditions on the buildings section | How many days before restrictions apply, and whether draining down or inspections are required |
Our guide to property owners' liability insurance explains how the liability section works, the limits landlords typically buy and the exclusions that catch owners out.
Disclosure and conditions
When you buy or renew landlord insurance, you may be asked whether you comply with your legal obligations as a landlord, or about specific safety checks. Answer accurately. If you say yes and the assessment was never done, an insurer may argue that the risk wasn't fairly presented. Some commercial and larger residential wordings also have conditions about water hygiene, particularly where there are cooling towers, spa pools or large stored systems. Read the conditions section, not just the cover summary.
A simple landlord legionella checklist
Map the water system: how hot water is made, whether there's a cold tank, and every outlet.
Identify risk points: stored water, low temperatures, little-used outlets, dead legs, spray sources.
Consider who lives there.
Put controls in place: cylinder at 60°C, tank lid fitted, pipes insulated, dead legs removed where you can.
Check temperatures with a thermometer, or ask your gas engineer to.
Flush the system before every new tenancy and during voids.
Tell tenants what they need to do and how to report problems.
Write it down, with the date and what you did.
Review it at each change of tenant, after work on the system, and at least as often as your gas safety check.
Check your landlord policy's liability limit, legal costs cover and unoccupancy conditions.
FAQs
Is a legionella risk assessment a legal requirement for landlords?
Yes. HSE's guidance is that landlords have a legal duty under HSWA and COSHH to assess the risk from legionella and control it. The law doesn't prescribe a form, a certificate or who must do it.
Can a landlord do their own legionella risk assessment?
Yes. HSE says most landlords can assess the risk themselves if they understand their water system and the controls. If you're not confident, or the system is complex, use a competent person.
Is there a legionella certificate for landlords?
No. There's no legal legionella certificate or "pass". What you need is a risk assessment and proportionate controls. Be wary of anyone who says you must buy a certificate.
Do I need to test the water for legionella?
Not usually. HSE says testing (sampling) isn't normally required for domestic properties. It's more relevant to larger or higher-risk systems, or where the controls in the assessment aren't working.
How much does a legionella risk assessment cost?
Doing it yourself costs your time and a thermometer. If you pay someone, the price depends on the property and the provider. Get two or three quotes and ask exactly what's included. A simple flat shouldn't need a lengthy report or sampling.
Does a combi boiler mean there's no legionella risk?
It means a lower risk, not zero. HSE notes combi boilers and electric showers reduce the risk because water isn't stored. You still need to think about little-used outlets, voids, showerheads and anything else that sprays water. Record that you've considered them.
Who is responsible for legionella in a block of flats?
Whoever controls each part of the system. The freeholder or managing agent is usually responsible for shared tanks and central plant. A leaseholder who lets their flat is responsible for the water system inside it. Check the lease and the management agreement.
Does landlord insurance cover legionella claims?
If a tenant or visitor makes a compensation claim, the liability section of a landlord policy is the part that may respond, subject to its terms, conditions and any exclusions. Some policies also include legal defence costs for health and safety prosecutions. Fines aren't insurable, and the cost of fixing the water system usually isn't covered.
Get your landlord cover reviewed
Send us your current landlord policy or your renewal notice. We'll check the liability limit, whether legal defence costs are included, the unoccupancy conditions and anything in the wording about water systems. Then we'll look for a better quote from the insurers on our panel and explain the differences in plain English. Start your landlord quote review.
Meshed is a trading name of Mesh'd Limited, authorised and regulated by the Financial Conduct Authority (FRN 1033248). We charge a flat 10% broker fee. This guide is general information for England and Wales unless stated otherwise. It isn't legal advice, and policy wordings vary between insurers.
Vincent Liu
Co-founder & CTO
