DIY vs Professional Legionella Risk Assessments: What Landlords Need to Know

Nothing in law says a Legionella Risk Assessment has to be carried out by a certified third party. For a landlord managing a single, simple property, that raises an obvious question: can you just do it yourself? The honest answer is, sometimes, but it’s worth understanding exactly what you’d be taking on with a DIY legionella risk assessment before you decide.

What “doing it yourself” actually involves

A proper Legionella Risk Assessment isn’t a five-minute visual check. Done properly, it means:

• Understanding the full layout of the property’s hot and cold water system, tanks, cylinders, pipework routes, and every outlet
• Taking and correctly interpreting temperature readings at multiple points (cold water should stay below 20°C, hot water should reach 60°C at the cylinder and 50°C at the tap within a minute)
• Identifying dead legs and infrequently used outlets, which often means knowing where pipework runs behind walls and floors, not just what’s visible
• Knowing what actually constitutes an acceptable risk versus one that needs remedial action, and being able to justify that judgement if it’s ever challenged
• Producing a written record that would hold up as evidence of due diligence

Where a DIY legionella risk assessment tends to fall short

In our experience, the gap isn’t usually about spotting an obvious problem, it’s about the things a non-specialist doesn’t know to look for. A cold water tank in a warm loft space, a shower that was fitted after the original plumbing survey, an outbuilding tap nobody remembers is there. These are exactly the conditions that create risk, and they’re easy to miss without training in what to check.

There’s also the liability question. If something did go wrong, a court would look at whether “suitable and sufficient” steps were taken, the same standard used across health and safety law generally. A landlord’s DIY legionella risk assessment can meet that bar, but it needs to be genuinely thorough, and being able to demonstrate the competency behind it matters more than most people expect.

What a professional assessment adds

A certified assessor brings a structured, repeatable process, the ABBE Level 2 Award in Legionella Awareness (the qualification our assessor holds) specifically trains for identifying and assessing these risks. In practice this means:

• A consistent methodology applied across every property, not a fresh judgement call each time
• Calibrated equipment for accurate temperature readings
• A written report that clearly documents findings, evidence, and recommendations, useful for your own records and for any letting agent, mortgage lender, or insurer who asks to see it
• Independent, professional evidence of compliance if it’s ever needed

Our view

For a single, straightforward property that a landlord knows well, a careful DIY approach isn’t unreasonable, provided it’s genuinely thorough and properly documented. For rented HMOs, multiple properties, or anything with a water system you’re not completely familiar with, a professional assessment is the more defensible and, frankly, less time-consuming route. Either way, the two-year review clock and the legal duty apply regardless of who carries it out.

If you’d like a professional Legionella Risk Assessment, taps-based pricing means a small property is quoted the same as an equivalent small business, get in touch for a quote.