Yes, a landlord in the UK has a legal duty to assess the risk from legionella in a rental property's water system and to control any risk found. But the Health and Safety Executive (HSE) says this does not need to be an in-depth assessment, most landlords can do it themselves, and there is no legal requirement to get a legionella test or a "legionella certificate". This guide explains what the law asks, how to carry out a simple assessment, how often to review it and what to tell tenants. It is general information, not legal advice.
The legal duty
HSE's guidance on legionella and landlords' responsibilities says landlords have a duty to assess the risk from exposure to legionella to ensure the safety of their tenants. The duty comes from general health and safety law, which treats a landlord who provides residential accommodation as responsible for the safety of the water system they supply.
HSE describes the practical, proportionate way to meet it: for a typical domestic rental the assessment does not need to be detailed. What matters is that you have looked at the risk, done something about it, and can show that you did.
What legionella is and why it matters
Legionella bacteria can grow in water systems and cause Legionnaires' disease, a serious form of pneumonia, when people breathe in small droplets of contaminated water, for example from a shower. The bacteria multiply in warm water that sits still, and in systems with debris, scale or unused pipework. Most domestic hot and cold water systems are low risk if the water is kept hot, kept cold and kept moving.
Do you need a legionella test or certificate?
No. HSE says health and safety law does not require landlords to obtain or produce a "legionella test certificate". It also says testing, or sampling, is not usually required for domestic hot and cold water systems and is only needed in very specific circumstances. Be wary of anyone who tells you a certificate is a legal requirement.
That does not mean doing nothing. The duty is to assess and control the risk. A short written assessment and a record of the steps you took is the sensible way to show you met it.
Who can carry out the assessment
HSE says most landlords can assess the risk themselves and do not need to be professionally trained. If you do not feel competent, or would rather not, you can arrange for someone to do it for you, such as a letting agent or a specialist. If you pay someone, the duty is still yours, so read what they produce and act on it.
A simple assessment, step by step
For a typical house or flat, walk through the water system and answer these questions:
- Hot water. Is there a hot water cylinder? HSE's landlord guidance says the cylinder (calorifier) should be set to store water at 60°C. Combination boilers that heat water on demand store little or no water, which lowers the risk.
- Cold water tanks. Is there a cold water storage tank in the loft? It should have a tight-fitting lid to keep out debris and vermin.
- Redundant pipework. Are there pipes that lead nowhere, such as a capped-off supply to a removed appliance? Remove them, as water sits still in them.
- Little-used outlets. Are there showers, taps or a spare bathroom that will not be used often? These need flushing.
- Empty periods. Has the property stood empty? Flush the system before a new tenant moves in.
- Who lives there. Note anyone at higher risk, such as older tenants or people with weakened immune systems. HSE's general guidance on hot and cold water systems says sampling may be needed where residents may be immunocompromised.
Write down what you found, what you did about each point and the date. That record is your assessment.
The control measures HSE lists
HSE sums up the approach as keep the hot water hot, cold water cold and keep it moving. For most domestic systems that means:
- flushing the system before letting the property;
- preventing debris getting into the system, for example with a tight-fitting lid on cold water tanks;
- setting the hot water cylinder to store water at 60°C;
- removing any redundant pipework.
HSE's guidance on hot and cold water systems adds detail that is useful for larger properties and HMOs: hot water at outlets should reach at least 50°C within a minute, cold water should stay below 20°C, infrequently used outlets should be flushed regularly, and showerheads should be cleaned and descaled.
What to tell your tenants
HSE suggests telling tenants to:
- leave the temperature setting on the hot water cylinder as it is;
- regularly clean and disinfect showerheads;
- tell you if the hot water is not heating properly or there are other problems with the system.
Put this in the move-in pack and the tenancy start paperwork. Our tenancy start checklist has space for it.
How often to review it
HSE says the law does not require the assessment to be reviewed every year or every two years, but it should be reviewed periodically in case anything changes. Good moments to review:
- before each new tenancy, especially after an empty period;
- after work on the plumbing, a new boiler or a new cylinder;
- when someone at higher risk moves in;
- when a tenant reports a hot water problem.
Scotland is more specific. mygov.scot tells private landlords they must assess the property for health risks associated with legionella, as part of the Repairing Standard.
Do you have to write it down?
HSE says landlords are not necessarily required to record the findings: the statutory duty to record applies to employers with five or more employees. Keeping a record is still the sensible choice, because it is the only way to show later what you checked and when.
HSE and council inspectors do not routinely inspect rented homes or ask for proof of an assessment. But HSE warns that if a tenant caught Legionnaires' disease from the water system, the landlord could face prosecution and would need to show they had met their legal duty. A dated assessment and a log of flushing and temperature checks is that evidence.
Empty periods and changeovers
The riskiest time for most rented homes is the gap between tenants. Water that sits in pipes, a tank or a little-used shower for weeks is the condition legionella needs. Before a new tenant moves in:
- run every hot and cold tap and the shower for a few minutes, so the water in the pipes is replaced;
- check the hot water cylinder is still set to 60°C and the boiler is working;
- look at the cold water tank, if there is one, and check the lid is in place;
- note the date and what you did on the assessment.
If the property will stand empty for a long time, arrange for someone to run the taps regularly, or flush the system thoroughly before anyone moves back in.
Letting agents and HMOs
If a letting agent manages the property, agree in writing who carries out the assessment, who flushes the system between tenancies and who keeps the record. Many agents offer it as part of full management. The legal duty remains with you as the landlord, so ask for a copy of whatever the agent produces.
Houses in multiple occupation usually have larger systems, more showers and more people, so the assessment takes longer. The same principles apply, and the extra checks in HSE's hot and cold water guidance, such as outlet temperatures and regular flushing of little-used outlets, become more relevant. Your HMO licence may set its own conditions too.
Keeping it with your other safety records
The legionella assessment sits next to the gas safety record, EICR, EPC and alarm checks. See our landlord compliance checklist, the short answer on whether you need an assessment and the glossary entry. VoxaMTD's paid plans let you record a legionella risk assessment against each property with the document, remind you when it is time to look again, and keep a sealed, dated record. See how VoxaMTD tracks each property's safety records.
Sources
All read on 2 November 2026.
- HSE: Legionella and landlords' responsibilities
- HSE: Hot and cold water systems, things to consider
- mygov.scot: repairs and maintenance as a private landlord
This guide is general information, not legal advice.