Updated: 27 September 2026. A rental property that has been empty for several weeks or months needs more attention than an occupied home because unused water can stagnate in the system. For landlords, the key Legionella controls before re-letting are to assess the actual risk, restore regular water movement and make sure the hot and cold water system is operating as intended.
Health and Safety Executive (HSE) guidance says landlords should carefully manage properties left vacant for extended periods. As a general principle, hot and cold water outlets should be used at least once a week during non-occupancy to maintain flow, with a suitable flushing regime or other measures considered where a property will remain empty for longer.
Vacant property Legionella checklist before re-letting
- Review the Legionella risk assessment if the vacancy or water system has changed the risk profile.
- Restore water movement. Stagnation should be avoided in hot and cold water systems.
- Flush the system before letting. HSE identifies this as a simple control measure for domestic rental properties.
- Check hot and cold water performance. Confirm the system is operating correctly.
- Inspect showers and outlets. Look for scale, dirt, damage or outlets that have been unused.
- Check stored-water components. Where tanks are present, make sure they are appropriately covered and maintained.
- Do not assume routine laboratory sampling is necessary. HSE says it is not usually required for ordinary domestic hot and cold water systems.
Why does vacancy increase Legionella risk?
Most occupied domestic properties are relatively low risk because water is used regularly and the system turns over. When a property is vacant, that regular movement stops.
HSE explains that water should not be allowed to stagnate within the system. Long periods of low or no use can create conditions that are less well controlled, particularly where water is stored, pipe runs are long, outlets are rarely used or temperatures are not being maintained effectively.
How often should water outlets be used in an empty property?
HSE states that, as a general principle, outlets on hot and cold water systems should be used at least once a week to maintain a degree of water flow and minimise the chance of stagnation.
For a property that will remain vacant for a long period, the landlord should consider a suitable flushing regime or other measures such as draining the system where appropriate.
The right approach depends on the system, so a large HMO, building with stored water or more complex communal system may need a more formal water-hygiene plan than a small flat with a combi boiler.
Should the system be flushed before a new tenant moves in?
Yes. HSE specifically lists flushing out the system before letting the property as a simple control measure.
The purpose is to replace stagnant water with fresh water and restore normal system operation before the new tenant starts using showers, taps and other outlets.
HSE’s current guidance is available at Legionella and landlords’ responsibilities.
Does a vacant property need Legionella laboratory testing?
Not automatically. HSE says routine Legionella testing or microbiological sampling is not usually required for ordinary domestic hot and cold water systems.
Sampling is used in more specific circumstances where the risk assessment, system complexity, control history or other evidence indicates that it is appropriate. Vacancy by itself does not mean every domestic property needs a laboratory test certificate.
HSE also makes clear that health and safety law does not require landlords to obtain a generic “Legionella test certificate”.
Should the Legionella risk assessment be reviewed after a long vacancy?
It can be appropriate. HSE says the risk assessment should be reviewed periodically and where circumstances change.
A prolonged vacancy can be a meaningful change because water-use patterns have altered. A review is especially useful where:
- the property has been empty for an extended period
- stored water is present
- the water system has been altered
- outlets have been isolated or left unused
- the hot-water system has been switched off or changed
- the building is an HMO or has a more complex communal system
- new occupants may be particularly vulnerable
What should landlords check before reoccupation?
A proportionate pre-letting review can include checking:
- whether hot water is heating correctly
- whether cold water is remaining appropriately cold
- whether all normal outlets are operating
- whether showers and spray outlets are clean and in good condition
- whether there are obvious signs of scale, debris or poor maintenance
- whether cold-water storage tanks, where present, are covered and maintained
- whether redundant pipework or rarely used outlets create avoidable stagnation
Where the system is complex or the landlord is not competent to assess it, professional water-hygiene support may be appropriate.
What about showers after a property has been empty?
Showers deserve particular attention because they create fine water droplets that can be inhaled. HSE advises tenants to clean and disinfect showerheads regularly, and a landlord should consider their condition when preparing a vacant property for reoccupation.
If a shower or outlet has been unused for a long period, it should form part of the property’s flushing and water-hygiene review before normal occupancy resumes.
What if the property has a combi boiler?
HSE notes that instantaneous water heaters such as combi boilers and electric showers can reduce certain risks because they do not store large volumes of hot water.
That does not remove the need to consider stagnant water in pipework and unused outlets. A small domestic system may remain relatively low risk, but the assessment still needs to reflect the actual property and period of vacancy.
What about HMOs and student accommodation?
HMOs and student properties can have predictable periods of low occupancy—for example, summer vacancies. HSE specifically uses student accommodation left empty over summer as an example of a property that needs careful water-system management during non-occupancy.
For larger HMOs, the landlord or manager should plan vacancy controls rather than waiting until the day before new tenants arrive. A documented flushing and inspection regime can make reoccupation easier to manage.
Should landlords keep records of flushing?
HSE says domestic landlords are not always under a statutory duty to record a simple Legionella risk assessment, but it can be sensible to keep records for management and evidence purposes.
For vacant properties, a basic record can show:
- the period the property was vacant
- dates of routine outlet use or flushing
- any system shutdown or draining
- maintenance completed
- the pre-letting review date
- any professional assessment or remedial action
Legionella support for vacant properties in London
Primelinks Solutions helps landlords, letting agents and property managers coordinate Legionella risk assessment and water-hygiene requirements across London.
- See our Legionella Risk Assessment service.
- Read legionella risk assessment service
- For HMOs, see the HMO Compliance Checklist.
- For multiple vacant or managed properties, use landlord compliance packs.
- For London coverage, see our London coverage page.
Frequently asked questions
How often should taps be run in an empty rental property?
HSE says that, as a general principle, hot and cold water outlets should be used at least once a week during vacancy to maintain flow and reduce stagnation.
Should a landlord flush the water system before a new tenant moves in?
Yes. HSE identifies flushing the system before letting as a simple and proportionate control measure.
Does an empty property need a Legionella test?
Not automatically. Routine laboratory sampling is not usually required for ordinary domestic water systems and should be based on the specific risk assessment and system circumstances.
Should the risk assessment be reviewed after a long vacancy?
It can be appropriate because vacancy changes normal water-use patterns. The assessment should be reviewed where circumstances have changed or existing controls may no longer reflect the system.
Preparing a vacant London property for re-letting?
Use Get a Quote and provide the property address, property type, approximate vacancy period, water-system details if known and whether there are stored-water tanks or several bathrooms/outlets.
This article provides general information and is not medical, legal or water-engineering advice. The appropriate controls depend on the water system, property use and assessed risk.