What should you do with your water system at work if you’re temporarily closing and actions to take before re-opening!


Where possible you should continue to flush your water systems regularly to maintain good circulation and avoid stagnation. You should also continue to carry out your monitoring tasks where possible, should access to your premises be available and safe to access. You should aim to keep your hot water hot and your cold water cold. Keeping the water moving and clean.

If you are unable to carry out the above then your water systems should be recommissioned as though they were new. Therefore, all employers MUST ensure the health and safety of their employees, customers, visitors and contractors by thoroughly flushing, clean and disinfecting and water testing before the building is re-occupied and the water systems returned to use.

Covid-19 and Legionella have a number of common symptoms, making it all the more important these actions to be completed to protect your health and safety and to avoid any extra burden on our incredible NHS.

Finally, you should update any risk assessments to reflect any actions or changes to your control measures.

Covid-19 Vs Legionella

The symptoms for Covid-19 and Legionnaires’ disease are very similar. With growing commercial and domestic properties being left unoccupied at this time, bacteria in water is of higher risk. Be sure to keep your water systems safe.

Keep in mind these symptoms when returning to properties that have been vacant and not used their water systems for over 7 days.



high temperature

a new continuous cough



a chesty cough

cannot breath properly

you have severe chest pains

high temperature

you feel like you have severe flu

Why should I be concerned about Legionella in an empty or partially occupied building?


When a building is unoccupied or there are less people using the building because it’s closed or people are working from home the health risks associated with its water systems, particularly growth of legionella and other dangerous waterborne pathogens will increase for a number of reasons.

  • The turnover of water is likely to stop or be significantly reduced, which may lead to stagnation. This can be very bad as it encourages bacteria and biofilm to grow at dangerous levels.
  • The cold water will tend to warm up whilst the hot water tends to cool down, entering into the ideal ranges for legionella growth.

If buildings water systems are allowed to become contaminated in this way there could be serious health consequences for those people still using the building or when everyone eventually returns to work.


What does the HSE recommend?


The Health and Safety Executives ‘HSG 274 Technical Guidance Part 2’ makes specific reference to this situation. It states on page 24:

Buildings temporarily taken out of use (mothballing)

2.50 Where a building, part of a building or a water system is taken out of use (sometimes referred to as mothballing), it should be managed so that microbial growth, including legionella in the water, is appropriately controlled.

2.51 All mothballing procedures are a compromise between adequate control of microbial growth, the use of water for flushing (while avoiding waste) and degradation of the system by any disinfectant added. Where disinfectants are used, these should leave the system fit for its intended purpose.

2.52 In general, systems are normally left filled with water for mothballing and not drained down as moisture will remain within the system enabling biofilm to develop where there are pockets of water or high humidity. The water in the system also helps to avoid other problems associated with systems drying out, including failure of tank joints and corrosion in metal pipework. The systems should be recommissioned as though they were new (ie thoroughly flushed, cleaned and disinfected) before returned to use.

Extremely happy with our legionella risk assessment carried out by uRisk, easy to understand and great customer service. Thanks again
Nickayla Robertson
Nickayla Robertson
21:22 15 Jan 19
uRisk have been helping us with our Legionella Control for a number of years now. We've recently had a CQC audit and they were very impressed with our legionella compliance! Thank you for all your help.
Mike Port
Mike Port
20:41 07 Aug 18
Brilliant company, customer service was great! And engineers were fantastic. Thanks again uRisk! Will definitely be using them for all future work.
Nikesh Gohil
Nikesh Gohil
12:49 12 Mar 18
Brilliant service! Thanks a lot for the hard graft
Leon Macauley
Leon Macauley
21:12 15 Jan 19
Brilliant Service, efficient, professional, punctual and friendly.
Alex Windsor
Alex Windsor
18:21 15 Jan 19
Fantastic training courses and we've found the legionella risk assessment very easy to read and far more detailed than any we have previously had. 5 star service!
Gemma Pond
Gemma Pond
20:37 07 Aug 18
A fabulous company, excellent customer service, they try to accommodate appoitments, and do there utmost in emergencies, been with them a few years now,  honestly cant fault them. Coming out of Covid 19, having our building urgently disanitised,  big thank-you to Luke and Lee for staying so late to get the job done!! Thank you Devon, for juggling the diary to fit us in so soon. A Team 🙂
Jo Maskell
Jo Maskell
18:02 15 Jun 20
We're a small GP practice and started using uRisk for legionella risk assessments. We opted to use their remedial and monitoring services and they've been absolutely great. We cannot recommend them enough! Thank you so much!
Amanda Pates
Amanda Pates
18:30 07 Aug 18
Incredibly detailed and professional team. Have been beyond helpful with with our CQC legionella compliance for our Safety. They’ve found solutions to fit around how we work and our budgets. We are always advised with reference to HSE which has been brilliant.
Amy Thorne
Amy Thorne
20:29 07 Aug 18

We want to help you comply!