Legionella risk assessment and guidance

What is Legionnaires' Disease?

Legionella is a type of pathogenic bacteria associated with water systems, including the water tanks, pipework, showerheads and whirlpool baths often found in domestic properties. If the bacteria become airborne (in water spray, mist or vapour) then they can be inhaled by residents and have the potential to cause a range of pneumonia-like illnesses.

Public Health England reported that during 2019, there had been 516 confirmed cases of Legionnaires’ disease. This is a relatively small number, but the health effects can be serious which is why it’s essential that Landlords do everything that they can to control the risks.

Assessing the level of risk

For most residential settings, the risk assessment may well show the risks are low, so long as simple control measures are followed.  This will apply to houses or flats with small domestic type water systems where the water turnover is high.

Provided the risk assessment shows that the risks are insignificant and the control measures are being properly managed, no further action would be necessary.  It is important however, to keep the assessment under review periodically in case anything changes to the system.

Are Landlords required to hire a consultant to perform Legionella sampling in addition to the control measures?

For straightforward residential accommodation, the answer to this will usually be "no" as long as Landlords are reasonably knowledgeable and competent.

HSE emphasise that Legionella testing/sampling is generally not required in domestic hot water systems and then only in exceptional circumstances. 

However, if a block of flats are involved, unless each flat has its own self-contained hot and cold water system, a more comprehensive risk assessment may be needed. 

Control measures

Simple control measures will help manage the risk from Legionella and these should be maintained including: 

• flushing out the water system by running all outlets for at least two minutes where the premises have not been used e.g. before letting the property or, if the property has stood empty for a time;
• avoiding debris getting into the system (e.g. making sure cold water tanks, if installed, have a tight fitting lid);
• setting controls so that the hot water is heated to and stored at 60°C;
• the removal of any redundant pipe work; and
• advising tenants to regularly clean, descale and disinfect shower heads.

Advice for tenants

Landlords are entitled to expect tenants to play their part in ensuring control measures are maintained and should:

• inform tenants of potential risk of exposure to Legionella and its consequences;
• tell tenants of any action which arises from the landlords risk assessment, if appropriate;
• tell tenants to inform the landlord or their agent if the hot water system is not heating properly, or if there are any other problems with the system;
• tell the Landlord or their agent if the cold water system is not running cold; and
• tell tenants to keep the water turned over.

Unoccupied premises

The risk from Legionella may increase if a property is unoccupied even for a short period, so it is important that water is not left to stand in the hot or cold water systems. As a general rule, all outlets on hot and cold water systems should be used at least once a week for at least 2 minutes to maintain a degree of water flow and minimise the chances of stagnation. For long periods, consider draining the system. Make sure that the system is flushed through when it is re-occupied by running all outlets for at least 2 minutes.

What is the letting agent's responsibility?

Landlords are responsible for making sure that the risks involving Legionella are properly assessed and controlled. Where a managing agent is used, the management contract should specify who has responsibility. Landlords must assume that unless the managing agent takes on this responsibility, they as the Landlord will be responsible for compliance.

What happens if the Landlord does not carry his/her obligation?

The consequences can be serious. Landlords are legally required to manage properties so as not to expose tenants, residents and visitors to risk. Heavy fines or even imprisonment can be imposed especially if someone were to unfortunately die. Landlords can be prosecuted even if there is an exposure to risk without anyone actually becoming ill.

Further information