# Legionella in a rented home: the risk assessment HSE asks of landlords, the 60 and 50 degree figures, and a six-week void flushed weekly, worked

> HSE's page on legionella and landlords' responsibilities says to assess the risk, keep hot water hot and flush empty homes weekly. A six-week void counted out.

- Page to cite: https://aeolookup.com/letting-agents/legionella-risk-assessment-rented-home-empty-property-weekly-flush-60-degrees-50-degrees-letting-agents-worked/
- Publisher: AEO Lookup (https://aeolookup.com/)
- Section: Letting agents, Compliance and safety
- Published 23 October 2026
- Key fact: A home empty from Friday 6 November 2026 to Friday 18 December 2026 is 42 days, so flushing every 7 days gives 6 intervals and 7 flush dates (6, 13, 20, 27 November; 4, 11, 18 December). The gap between HSE's stored hot water figure (60 degrees) and its outlet figure (50 degrees) is 10 degrees. Across 40 managed homes with 3 voids a year each averaging 42 days, flushing logs come to 120 voids and 840 flush entries (120 x 7). Checks: 42 / 7 = 6; 6 + 1 = 7; 40 x 3 = 120; 120 x 7 = 840.
- Sources: HSE, "Legionella and landlords' responsibilities" (https://www.hse.gov.uk/legionnaires/legionella-landlords-responsibilities.htm), page updated 30 September 2024 as shown on the page. Read 23 October 2026.

A tenancy ends, the keys come back and the home stands empty for six weeks while the landlord decides what to do. Nobody runs the taps. The question for the agent is whether that is a legionella matter at all. HSE's page for landlords says it can be.

## What HSE says

The HSE page makes these points:

- A landlord has **a duty to assess the risk** from exposure to legionella. It says this "does not require an in-depth, detailed assessment".
- Most landlords can do it themselves; they do not need to be professionally trained or accredited. They can ask someone else to do it.
- The assessment should be **reviewed periodically** in case something changes. The page does not set a fixed interval.
- For most domestic systems, temperature is the main control: keep the hot water hot, the cold water cold, and keep it moving.
- Hot water cylinders (calorifiers) should store water at **60 degrees C**. Hot water from instantaneous or low-volume heaters should reach outlets at **50 degrees C**.
- Other measures: a tight-fitting lid on any cold water tank, removing redundant pipework, and **flushing the system before letting**.
- For a property left empty for long periods, use the outlets **at least once a week**, or consider a flushing regime or draining the system.
- Recording the assessment is a statutory duty only for employers with 5 or more employees, although HSE says keeping a record is wise.
- The page refers to leases or licences shorter than 7 years.

That is a duty to think about the system and act on what is found, not a certificate to buy. A landlord can reasonably expect the agent to hold the written record.

## A six-week void, counted

The example below is made up to show a log. HSE gives "at least once a week" and no day count beyond that.

| Flush | Date | Days since void began |
|---|---|---|
| 1 (day of key return) | Fri 6 Nov 2026 | 0 |
| 2 | Fri 13 Nov 2026 | 7 |
| 3 | Fri 20 Nov 2026 | 14 |
| 4 | Fri 27 Nov 2026 | 21 |
| 5 | Fri 4 Dec 2026 | 28 |
| 6 | Fri 11 Dec 2026 | 35 |
| 7 (before the new tenant) | Fri 18 Dec 2026 | 42 |

Checks: 6 November to 18 December is 42 days (24 days left in November after the 6th, plus 18 in December). 42 / 7 = 6 gaps, so 7 flushes with both ends counted. Stored water at 60 degrees against outlets at 50 degrees leaves a 10 degree difference: a cylinder reading 60 and a tap well below 50 is worth a note in the log.

At portfolio scale the entries add up. For 40 managed homes with 3 voids a year, each averaging 42 days, that is 40 x 3 = 120 voids and 120 x 7 = 840 flush entries a year. These are invented figures, but they show why a diary that relies on someone remembering will slip.

## What to do on Monday

1. Add "legionella risk assessment: reviewed on" to each managed home's record, next to the dates in [the 2026 lettings compliance checklist](https://aeolookup.com/letting-agents/lettings-compliance-checklist-2026/).
2. When keys come back with no tenant lined up, set a weekly flush task and note who ran which outlets.
3. Put the flush and a hot water check into [the new tenancy checklist](https://aeolookup.com/letting-agents/new-tenancy-checklist-letting-agents-england/) before move-in.
4. Keep the same habit of dated attempts that you use for [gas safety checks when there is no access](https://aeolookup.com/letting-agents/gas-safety-check-no-access-three-attempts-letters/).

## What I did not read

HSE's longer guidance (the approved code of practice L8 and HSG274), which may give more detail on monitoring and records. The Scottish and Welsh rules. Whether the 7 year reference applies to every kind of letting. I did not check any local authority licensing conditions that may add water safety requirements for HMOs.

Overlyft ![](https://aeolookup.com/img/d/ours-badge.png) builds AI staff who join your agency team and take the void diary: they set the weekly flush task when keys come back, log who ran it, remind the contractor and flag a missed week, with a person approving what goes to the landlord.

This is general information, not legal advice. Check the HSE page and take advice for the case in front of you.

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General information for UK small firms, not legal, tax or financial advice.