Can I do my own legionella risk assessment?
Updated 7 September 2026
Short answer
For a simple domestic let or a small commercial premises, yes. ACOP L8 does not require the assessor to be an external contractor. What it requires is competence. If you can understand your water system, apply the guidance in HSG274 Part 2, and document the assessment properly, you can do it yourself.
The question comes up most often from landlords and small business owners who have had a quote from a contractor and are trying to work out whether they really need to pay it. The honest answer is that for many premises you do not, and self-assessment is explicitly supported by HSE guidance.
When self-assessment is appropriate
The following situations are generally suitable for self-assessment:
- Single domestic lets with a combi boiler and no stored water
- Small offices with a single hot water cylinder and no showers
- Shops with a single toilet and a kettle
- Holiday lets with simple modern plumbing and no hot tub
- Small dental or veterinary practices with straightforward water systems (dental unit waterlines are a different matter)
In all these cases, a written assessment using a template, a simple control scheme, and basic temperature monitoring are enough to discharge the duty.
When you should use a contractor
Self-assessment is not appropriate for:
- Care homes, hospitals, and any premises with vulnerable occupants
- Premises with a cooling tower or evaporative condenser
- Leisure facilities with pools, spa pools, or steam rooms
- Schools and large hotels
- Any premises where the water system layout is not fully documented
- Any premises where a previous sample has exceeded the action threshold
In these situations the technical complexity, the consequences of error, and the level of record keeping required put the work beyond what most non-specialists can reasonably do.
How to self-assess competently
If you do self-assess, be honest with yourself about what you know. Read HSG274 Part 2 in full. Walk the entire water system and mark it up on a building plan. Note every outlet, every calorifier, every cold water tank, and every dead leg. Measure temperatures over at least one full monitoring cycle. Record the assessment in writing, date it, and sign it. Review it when anything changes.
Self-assessment does not mean informal assessment. The document you produce should be as detailed as the one a contractor would produce for the same system. It is the quality of the work that matters, not who does it.
Legal basis
ACOP L8 paragraph 40 on the duty to ensure the assessment is carried out by a competent person. HSE guidance for landlords (INDG458) on self-assessment for domestic rented property.
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Free legionella risk assessment template
A structured Word document following the five-step approach in ACOP L8. Covers risk identification, written scheme, monitoring, and records. If it isn't written down, you can't evidence it.
Follows ACoP L8 and HSG274 Part 2. Free. No spam.