Water Hygiene Guidance for Building Reoccupation

Post Lockdown – Water Hygiene Planning and Management


As the current situation progresses and thoughts turn to returning to work, we have prepared guidance for clients to assist them in planning.  This note refers to water hygiene management.


Clearly, it is important for building occupiers to adopt a systematic approach to reoccupation of vacated buildings and rooms post-lockdown.  The guidance outlined below gives a number of areas and recommendations which can be used to frame thinking as buildings and rooms are put back into use.


During the lockdown period and after, The Health and Safety at Work etc Act still applies and, as such, Duty Holders must take all reasonably practicable steps to control the risk from legionella (and other waterborne pathogens) throughout this time. Advice given by the LCA [Legionella Control Association] would indicate that the HSE is unlikely to treat this COVID-19 lockdown as any exemption to the Duty Holder being prosecuted should it be shown their actions [or lack of] caused a case of Legionella or Legionella outbreak.


For each property/water system, a recommissioning plan should be detailed. The number of steps in this plan will vary depending on the complexity and size of the water systems and importantly on the people who will be using these systems, this includes those undertaking the recommissioning works.

In order to formulate a recommissioning plan, you should consider the following:-

  1. How many buildings (or rooms) need to be recommissioned?
  2. When is the building or room due to be reoccupied?
  3. From this date we need to work back on the calendar to allow enough time for each step to be completed. What are the tasks that you need to complete for the water system(s) to be recommissioned? How long does each step take to complete?
  4. Who is going to be carrying out each step? Can they / you prove that they have received suitable Legionella training and are they competent? If not, can you assist through delivery of the required training to produce this assurance?
  5. Do you have a partial reoccupation that will require any additional flushing/monitoring until full occupation?

Due to the current lockdown there are additional factors that will need to be considered: –

  • How many other staff / contractors will be in the building and are they able to maintain social distancing?
  • What is the availability of staff to carry out the works? If you’re using sub-contractors to help with this process it is likely that there will be multiple organisations all asking for their services to help with recommissioning around ‘What is the availability of staff to carry out the works’? If you’re using sub-contractors to help with this process it is likely that there will be multiple organisations all asking for their services to help with recommissioning around the same time, so you will need to confirm what resources they have and when…
  • What is the availability of equipment, chemicals and test equipment to measure the chemical levels? Both internally and externally
  • What PPE is to be worn by those members of staff carrying out the works? Will there be sufficient available for them to complete the work in accordance with COSHH and the Material Safety Data Sheet?
  • The requirement for microbiological samples to be taken post [2-7days] disinfection, and for these to be submitted to a UKAS accredited laboratory. Will the laboratory have the capacity to receive and process these samples within the time limit for the samples to be viable?
  • What if the sample results show there is still bacteria present in the water, would this prevent reoccupation, or could additional temporary controls be applied / installed to allow the reoccupation and keep the building users safe?

In order to manage your responsibilities, it is our recommendation that you take the opportunity NOW to develop these recommissioning plans, in conjunction with other stakeholders, so that these can be rolled out and followed to allow properties to return to normal operation as quickly as possible.

The initial plan could be a spreadsheet of all the buildings or rooms listed in priority order of reoccupation, with details from the Legionella risk assessment of the water systems and assets within that building or room (e.g. 2 x cold water tanks and 2 x domestic hot water generators, 75 outlets with 25 TMVs). This information will help with the scheduling of the recommissioning work based on the availability of resources [staff / contractors, equipment, disinfectants and samples to be taken and processed].

Finally, once the building has been recommissioned the water systems should not be allowed to stagnate again, so if not reoccupied immediately then you will need to initiate a flushing strategy of all the outlets until occupation.

The guidance above should allow building inhabitants to plan for reoccupation and will enable them to identify risks associated with their water system, and how they should mitigate these risks as they return to normal operation.

If you have any further questions, or require more detailed guidance, please contact steve.hanson@wearecallidus.com , who will be happy to help.