Landlords are sold legionella certificates constantly, and the certificate is not what the law asks for. HSE could hardly be clearer: health and safety law does not require landlords to obtain or produce a legionella test certificate. What it does require is that the risk from the water system is assessed and controlled, which is a different thing and usually a cheaper one.
What the duty actually is
A landlord letting residential property is conducting an undertaking, so section 3 of the Health and Safety at Work etc. Act 1974 makes them responsible for the safety of their tenants in respect of it, and COSHH covers the biological agent. The duty is to assess the risk from the water system and to put proportionate control measures in place. For most domestic properties HSE describes those measures as simple, cheap and effective.
What a low risk property looks like in a domestic legionella risk assessment
HSE describes it: daily water usage that is inevitable and sufficient to turn over the entire system, cold water direct from a wholesome mains supply with no stored water tanks, hot water from instantaneous heaters or low volume water heaters supplying outlets at 50°C, and outlets limited to toilets and wash hand basins. A simple assessment may show there are no real risks and that they are being properly managed, so no further action is needed.
What actually raises the risk
Stored water in a tank, particularly one without a tight fitting lid. A calorifier not reaching temperature. Showers, because they atomise. Dead legs and redundant pipework left after a conversion. And vacancy, which is why student lets and holiday properties need a flushing regime or draining down. HSE's general principle is that outlets should be used at least once a week to maintain flow and minimise stagnation.
Recording it
HSE states that landlords are not necessarily required to record the findings, because that is a statutory duty for employers where there are 5 or more employees, but that it is wise to keep a record for your own purposes. That record is what you would rely on if a tenant contracted the disease, because the landlord would have to demonstrate to a court that they had fulfilled their legal duty.
Whether anyone will ask to see it
HSE and local authority inspectors do not proactively inspect domestic premises or ask landlords for evidence that they have carried out a risk assessment. Letting agents and insurers often do, which is a commercial requirement rather than a legal one, and it is worth knowing which of the two you are answering when a firm quotes you for a certificate.
How long to run shower for legionella, and when flushing is the wrong answer
Flushing an unused outlet means running it until the water reaches its normal temperature and then a little longer, which on a shower is typically a few minutes rather than seconds, and the common guidance for an infrequently used outlet is weekly. The detail that gets missed is the AEROSOL: a shower spray is exactly the route by which the organism reaches the lungs, so flushing a shower that has stood for weeks should be done with the head removed and the hose run into the tray, or with the head immersed, and with the room left to clear afterwards. Where flushing is the wrong answer is a system that has been stagnant for months, or one that cannot hold its temperatures: running the water there generates aerosol from the worst possible water, and the right sequence is to disinfect the system, clean or replace the showerhead and hose, and then bring it back into use under a flushing regime.
Legionella prevention in a let property, month by month
For a normal house or flat the regime is short and the calendar is what makes it real. At every change of tenancy, and after any void, flush all outlets, clean and descale the showerhead and hose, and check the hot water temperature at the tap. Monthly, or at whatever interval the assessment sets, flush anything that is not in regular use: a second bathroom, an outside tap, a utility sink. Quarterly, clean and descale showerheads, which is the single most useful maintenance task in a domestic system. Annually, review the assessment and check the cylinder's thermostat setting if there is one. Where the property is a combination boiler with no stored water and no shower hose sitting full, the risk is genuinely low and the assessment should say so rather than inventing a regime, but that conclusion is a recorded finding rather than an assumption.
Questions people ask about legionella certificate
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. The duty is to assess and control the risk.
Is a legionella risk assessment mandatory for landlords?
Assessing and controlling the risk is a legal duty. For a simple domestic system that assessment can be short and can conclude the risk is low and already managed.
Can a landlord do their own assessment?
Yes. HSE says most landlords can assess the risk themselves and do not need to be professionally trained or accredited, and can arrange for someone else to do it if they do not feel competent.
What happens if a tenant catches Legionnaires' disease?
The landlord may be liable to prosecution under the Health and Safety at Work etc. Act 1974 and would have to demonstrate to a court that they had fulfilled their legal duty, which is why keeping a record of what was assessed and controlled matters.
What does a legionnaires assessment cover in a let home?
The water system as it is: how it is heated, where water sits still, whether temperatures are what they should be, and who uses it. In most small domestic systems the conclusion is low risk with simple controls, which is a finding rather than a formality.
Is a legionnaires risk assessment for landlords a separate document?
No, it is the same assessment applied to a let property, and in most small domestic systems it is short. What makes it a landlord duty is control of the premises, not the size of the system.