How to do your own legionella risk assessment

Twelve steps, in the order you walk the house.

1. Take a probe thermometer and your phone. A digital thermometer with a probe, about £20 from a DIY shop; not an infrared one, which reads the surface, not the water. The phone is for photographs. Make sure you can reach every tap and shower, and the loft if water is stored there.
2. Find where the water comes in. Locate the stop tap and the incoming main, and follow where the cold water goes from there: straight to the taps, or into storage first.
3. Find where water is stored, if anywhere. A cold water tank: check it has a close-fitting lid, that nothing has got in, and that the water is clean. A hot water cylinder: stored hot water should reach 60 °C. A combi boiler stores none, and the assessment is shorter.
4. Take a temperature at every tap and shower. Hot should reach 50 °C within a minute of running. Cold should be below 20 °C within two minutes. Write the reading down, not a tick.
5. Look for water that does not move. Outlets nobody uses: a spare en-suite, an outside tap. Pipework that goes nowhere after a refit. HSE lists making sure any redundant pipework identified is removed.
6. Check the showers. A shower makes a spray that can be breathed in. Look at each head for scale; scale gives bacteria somewhere to settle.
7. Note who lives there. People over 45, smokers and heavy drinkers, and anyone with a lung, heart or kidney condition, diabetes or a weakened immune system are more at risk. It changes how quickly things need doing.
8. Photograph what you find. One photograph beside each finding. A tank with no lid is a sentence; a photograph of it is evidence.
9. Write down the findings and the actions. For each problem: what it is, why it matters, what will be done, by whom and by when.
10. Write the routine: the scheme of control. What will be done routinely to keep the risk low: stored hot water kept at 60 °C, outlets nobody uses run weekly, shower heads cleaned and descaled, the system flushed before each new tenancy.
11. Tell the tenant. HSE says tenants should be told the control measures to keep up: not adjusting the temperature setting of the hot water cylinder, regularly cleaning shower heads, and telling you if the hot water is not heating properly.
12. Set a review date. There is no fixed legal interval. Review it periodically, and whenever the water system, its use or the people living there change.

The control measures and the tenant advice are on HSE’s page on legionella and landlords’ responsibilities.

The same steps, on your phone, and the write-up done.

DwellFlow asks each question at the property, in the order that suits the house you are standing in, and applies HSE’s guidance to every answer. You take the readings and the photographs. The AI checks the survey before you submit, then writes the risk assessment, a sheet for your tenant and the written scheme of control, with the review date set. £9.99 ex VAT a property.