Landlords: there's no such thing as a 'legionella certificate'

A letting agent, or a firm cold-calling your managing agent, tells you the property needs a legionella certificate. Renewed every year. Produce it or you're breaking the law. It sounds official enough that most landlords just pay and file the PDF.

There is no such document in law. Health and safety law does not require a legionella certificate, and the body that writes the rules says so in plain words. HSE: "Health and safety law does not require landlords to obtain or produce a 'legionella test certificate.'" What the law does require is real, but it is different from, and lighter than, the sales pitch implies.

The duty is to assess the risk. In HSE's words again, "there is a duty to assess the risk from exposure to legionella to ensure the safety of their tenants, this does not require an in-depth, detailed assessment." The duty holder is you, the landlord, or the managing agent where they are the one in actual control of the property. The legal hooks are section 3(2) of the Health and Safety at Work etc Act 1974 and the Control of Substances Hazardous to Health Regulations. No certificate appears anywhere in either.

Most landlords can do the assessment themselves

This is the part the certificate sellers would rather you skipped. HSE: "Most landlords can assess the risk themselves and do not need to be professionally trained or accredited." For an ordinary domestic let with a combi boiler and no stored water, the assessment is short and the risk is genuinely low.

A self-assessment is mostly a matter of looking for the conditions legionella needs and confirming they aren't there:

• Stored or stagnant water sitting in the temperature band where the bacteria grow.
• Outlets that go unused for stretches, so water stands in the pipe rather than moving through it.
• Debris, sludge or a missing lid on any tank or cistern.
• Hot water that isn't kept hot and cold water that isn't kept cold.

Write down what you found and what you did about it. That is the assessment. It is not a lab test, and it is not a certificate.

The annual-renewal framing has no legal basis either. HSE is explicit: "The law does not prescribe that the risk assessment be reviewed on an annual or biennial basis." You review when something changes: a new tank, a bathroom added, a long void, not because a calendar reminder or an invoice says twelve months are up. We pulled that particular myth apart in the two-year review myth, because it costs landlords real money for a review that changes nothing.

If a managing agent runs the property

The duty holder is whoever is in control of the property, and where you use a managing agent that can be them rather than you. It depends on what the management agreement actually hands over. If the agent controls the building, arranges the maintenance and holds the relationship with the tenant, the legionella duty can sit with the agent. If you have handed over the day-to-day but the contract says nothing about water safety, you have a gap where each side assumes the other is dealing with it. Neither assumption is a defence. Settle it in writing in the management contract, name who assesses the risk and who acts on what the assessment finds, and keep a copy. An unnamed duty is an unmet one, and it is the landlord who tends to be standing there when it goes wrong.

Where an HMO changes the picture

A house in multiple occupation is not a one-bed flat, and the low-risk logic doesn't stretch to cover it. Three things tend to raise the profile. Communal cold-water storage tanks feeding several units. Showers in shared bathrooms that go days without use. Older or extended plumbing carrying dead legs where water sits still. Any one of those can move an HMO out of the quick-self-assessment bracket.

For HMOs, an annual inspection of the cold-water storage tank and monthly temperature checks are treated as good practice. Not because a certificate demands it, but because the risk is real enough to keep an eye on. Run several HMOs and that becomes a small recurring routine rather than a one-off form, and it is the point where a lot of landlords hand the work to a water hygiene contractor. Sensible. Just be clear about what you are handing over, which is the last section of this piece.

The myth distracts from the risk that reaches a tenant

Here is why the certificate myth is worth killing rather than shrugging off. It sells you a piece of paper that changes nothing about your property, while the risk that actually reaches a tenant goes unlooked at. The stagnant en-suite in a part-let HMO. The void flat where nobody ran a tap for six weeks over the summer, and the first tenant back gets a warm, aerated shower off a dead leg. A certificate in a drawer does nothing about either of those. A proportionate assessment, followed by acting on what it finds, does.

So spend the attention where the exposure is. Flush the outlets that sit unused between tenancies. Keep cold water cold and hot water hot. Look at the shared bathrooms in the HMO before you look at the paperwork. The point of the exercise is a safe tenant, not a satisfied filing cabinet.

What you should actually keep

You do not need a certificate. You should keep the risk assessment itself, and a record of any checks or flushing you do, so that if a tenant or an environmental health officer ever asks, you can show the risk was assessed and controlled. HSE accepts records in digital form, provided they are authenticated so you can tell who recorded what and when. We set out the tests digital records have to pass separately.

One boundary matters more than any of the above, and it holds whether you self-assess or pay a specialist. You can hire someone to carry out the assessment and do the flushing. You cannot hand them the duty. If control fails and a tenant is harmed, the duty holder answers for it, not the contractor who sent the engineer. Knowing who holds the duty versus who does the competent work is the difference that decides who stands in front of the regulator.

For a water hygiene contractor managing this across a portfolio of landlords and HMOs, the record is the whole product. Every assessment, every monthly temperature, every void flush, held against the right property and kept past the retention period, so that when one landlord's HMO gets a query the answer is a lookup rather than a hunt through emails. That is the flat, unglamorous evidence base BlueWave's compliance records exist to hold. For a single landlord with one flat, honestly, a dated note in a folder is enough, and you should not let anyone tell you otherwise.

The test for whether you have met the duty is not whether you hold a certificate. It is whether you can say, in a sentence, what the legionella risk is in your property and what you do about it. If you can, you have already done more than the certificate ever would.