Legionella risk assessment for landlords: what the law requires
Every landlord in the UK has a legal duty to assess and control the risk of legionella in the hot and cold water system of a rented home, including a single room let in your own house. For most homes this is a short, simple assessment, not a specialist survey, and the Health and Safety Executive says most landlords can do it themselves. There is no legal requirement for a legionella test or a legionella certificate, and no fixed renewal date. What matters is that you have looked at the system, dealt with anything that lets water sit warm and stagnant, told your tenants what they need to do, and review it when something changes.
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Discuss your plumbing workWhere the duty comes from
The Health and Safety at Work etc. Act 1974 applies to landlords as well as employers. Under it, and under the Control of Substances Hazardous to Health Regulations (COSHH), anyone who rents out a property must make sure tenants are not exposed to health risks from the way the property is run. Legionella bacteria in the water system are one of those risks.
HSE's Approved Code of Practice L8 and its technical guidance HSG274 explain how the duty is met. For ordinary rented homes, HSE's own guidance is clear that the assessment should be proportionate. A flat with a combi boiler, mains-fed cold water and a shower that is used every day is a low-risk system, and the assessment can say so.
The duty covers private landlords, letting agents acting for them, housing associations, councils, and people who take in a lodger. A lease or licence of less than seven years counts.
Why legionella matters in a home water system
Legionella bacteria live naturally in water at low levels. The risk comes when they multiply and the water is then breathed in as fine droplets, most often from a shower. That can cause Legionnaires' disease, a serious form of pneumonia, which is more dangerous for older people, smokers and people with weakened immune systems.
The bacteria multiply in water between about 20°C and 45°C, especially where it sits still and where there is sludge, scale or rust for them to feed on. So the whole approach comes down to three things: keep hot water hot, keep cold water cold, and keep it moving.
What a landlord's assessment should look at
Walk through the property and note how water is stored and heated, and where it could stand unused. These are the points that change the risk.
| Feature | Why it matters | Typical control |
|---|---|---|
| Combi boiler or electric shower | No stored hot water, so the risk is lower | Normal use; clean showerheads regularly |
| Hot water cylinder | Stored water can sit at growth temperatures if set too low | Store at 60°C and make sure the thermostat works |
| Cold water tank in the loft | Stored cold water can warm up and collect debris | Tight-fitting lid, insulation, and check it is clean |
| Dead legs and redundant pipework | Water stands still in pipes that no longer lead anywhere | Remove the redundant pipe back to the live supply |
| Little-used showers and taps | Water stagnates between uses | Run them weekly, or remove them if never used |
| Empty periods between tenancies | The whole system stagnates | Flush all outlets before the next tenant moves in |
Who can carry out the assessment
HSE says most landlords can assess the risk themselves and do not need to be professionally trained or accredited. You need to understand how your hot and cold water system works, recognise the conditions that let bacteria grow, and put simple controls in place.
If you are not confident doing that, or you manage several properties, you can ask someone competent to do it for you. Larger or more complex buildings, such as HMOs with large stored hot water systems, blocks with shared tanks, or properties with spa baths, deserve a more detailed look. Our guide to HMO hot water demand planning covers how stored hot water is usually arranged in shared houses.
Be wary of anyone who says the law requires an annual legionella test or certificate. HSE states that health and safety law does not require landlords to obtain or produce a legionella test certificate, and water sampling is only needed in very specific circumstances.
Simple controls that keep the risk low
HSE's guidance for landlords lists straightforward physical measures. In practice most of them are small plumbing jobs or settings you can check on a routine visit.
Storing hot water at 60°C raises the risk of scalding at the tap, particularly for children and older tenants. A thermostatic mixing valve on the bath or basin lets you keep the store hot and the outlet safe.
Our guide to hot water cylinder temperature explains how to check the setting at a tap with a thermometer and where the thermostat sits on different cylinders.
- Set the hot water cylinder to store water at 60°C and ask tenants not to turn it down
- Make sure cold water tanks have a tight-fitting lid and are free of debris
- Remove redundant pipework and dead legs left from old appliances or refits
- Flush the system through before a new tenancy starts
- Ask tenants to clean and descale showerheads regularly
- Ask tenants to report hot water that is not heating properly
- Keep outlets in use at least once a week, especially in empty properties
What to tell your tenants
Part of the duty is making sure tenants know about the controls they need to keep in place. A short note in the move-in pack is usually enough: do not lower the cylinder temperature, clean showerheads every few months, run any shower or tap that has not been used for a week or more before using it, and report problems with hot water straight away.
Tenants are also your early warning. Lukewarm water from a cylinder, a tank overflow dripping outside or a shower that has sat unused in a spare room are all worth hearing about.
Records and reviewing the assessment
Landlords are not always legally required to write the assessment down. That is a statutory duty for employers with five or more employees. HSE still recommends keeping a record of what you checked and did, because if a tenant became ill you would have to show you had met your duty.
There is no fixed legal interval for reviewing it. Review it when something changes: a new boiler or cylinder, a bathroom refit, a change of tenant, a long empty period, or a report of poor hot water. Routine visits, such as the annual gas safety check, are a practical time to look at the cylinder temperature and the tank. Our landlord plumbing maintenance checklist sets out what to look at on each visit, and what certificates does a landlord need covers the other documents.
Empty properties and changeovers
Stagnant water is the biggest single risk in rented homes, and it builds up fastest when a property is empty. HSE advises that outlets should be used at least once a week. For a longer void, either arrange for someone to run every tap and shower weekly, or drain the system down if it will stand empty for a long time.
Before new tenants move in, run each hot and cold outlet in turn until the water runs at its normal temperature, starting with the one nearest the tank or cylinder. Shower heads can be removed and cleaned first so the spray does not throw fine droplets while the pipe clears. The void property plumbing checklist and our guide to drinking water after a property is left empty cover the rest of the changeover.
Getting the plumbing work done
Most assessments end with a short list of plumbing actions: remove a dead leg, replace a cold water tank with no lid, fix a cylinder thermostat that no longer holds temperature, or take out a tank that is no longer needed. Our guide to retiring a cold water storage tank explains when a tank can go altogether.
Loyal Plumbers carries out this work for landlords and managing agents across London and everywhere inside the M25, with 10 vans available 24 hours a day. Send us the findings or the list of actions, the property address and how access is arranged, and we will tell you what each item involves before any work starts. See our general plumbing and property manager plumbing pages for the kind of work we cover.
Common questions
- Is a legionella risk assessment a legal requirement for landlords?
- Assessing and controlling the risk is a legal duty under health and safety law. For most homes the assessment is short and simple, and the landlord can usually carry it out themselves.
- Do landlords need a legionella certificate?
- No. HSE states that health and safety law does not require landlords to obtain or produce a legionella test certificate, and water testing is not usually needed in homes.
- How often should a landlord's legionella assessment be reviewed?
- The law does not set an interval. Review it when anything changes, such as new heating, a refit, a new tenant or a long empty period, and check the basics on routine visits.
- What temperature should a hot water cylinder be set to?
- HSE guidance is to store hot water at 60°C. Water should reach outlets hot, and tenants should be asked not to turn the cylinder thermostat down.
- Are combi boilers lower risk for legionella?
- Yes. A combi heats water as it is used, so there is no stored hot water. The risk is lower, though showerheads still need regular cleaning.
Sources and further reading
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