Houses in multiple occupation (HMOs) can have more complicated water-use patterns than a typical single-family rental. Several bathrooms, shared kitchens, additional showers, converted lofts and extensions can all affect how water moves through a property. For London landlords and managing agents, the important question is not whether an HMO needs a special “Legionella certificate”, but whether the actual hot and cold water system has been properly assessed and the identified risks are controlled.
Why HMOs deserve a site-specific assessment
HSE guidance makes clear that landlords have duties to assess and control risks from Legionella. In many ordinary domestic properties the risk is low because water is used frequently and the system is simple. An HMO, however, may have more outlets, more occupants, additional hot-water equipment or parts of the system that are used unevenly.
Common HMO risk factors
- Several showers or bathrooms serving different floors.
- Loft conversions or extensions with long pipe runs.
- Spare or vacant rooms with little-used outlets.
- Cold-water storage tanks in older London properties.
- Hot-water cylinders, secondary circulation or multiple heaters.
- Thermostatic mixing valves fitted to some outlets.
- Redundant pipework left after refurbishment.
Does an HMO need routine Legionella testing?
Not automatically. HSE states that microbiological sampling is not usually required for domestic hot and cold water systems and that landlords are not required to obtain a “Legionella test certificate”. Testing may be appropriate in particular circumstances, but it should follow from the risk assessment rather than replace it.
What should landlords and agents check?
A practical assessment should identify the water-system layout, storage arrangements, hot-water generation, shower facilities, little-used outlets and any conditions that could encourage stagnation or poor temperature control. Where simple control measures are appropriate, these may include maintaining suitable system temperatures, removing unnecessary pipework, managing vacant rooms and keeping showerheads or hoses clean.
When should the assessment be reviewed?
Review is sensible after significant plumbing work, changes in occupancy, prolonged vacancy, addition of bathrooms or showers, replacement of water heaters, or where existing controls are repeatedly failing. The law does not prescribe a fixed annual or two-year review interval for domestic landlords; the review should respond to changes and evidence that the previous assessment may no longer be valid.
For broader landlord guidance, see our article Do London Landlords Need a Legionella Risk Assessment?
Official guidance: Health and Safety Executive (HSE) L8 Approved Code of Practice, HSG274 Part 2, and Legionnaires’ disease: what you must do.
Need an HMO assessment in London? London Legionella Water Survey can review the property’s actual hot and cold water system and provide a proportionate, site-specific report. Contact info@londonwatercompliance.com.uk.