Legionella: Guidance for Re-Opening and Re-Occupation of Buildings: Hot and Cold Water Services

Quantum Compliance has issued general advice on management of water systems during the Covid-19 pandemic on 25th March. This was followed by a further advice note on 3rd April, with more specific and practical advice for hot and cold water systems, and evaporative cooling systems.

Feedback from Legionella risk assessments, carried out since the official lockdown at the end of March can be found below.

The Legionella Control Association (LCA) has issued guidance on Reopening Buildings, which is summarised below.

  • Simply reopening a building that has stood idle, without addressing the safety of its water system is unacceptable and is likely to be in breach of the law.
  • If Dutyholders are not able to put in place a proper recommissioning process to use the water system safely, they should not reopen the building.
  • Buildings that have remained empty with static water systems, or those that have been subject to limited flushing that does not represent normal usage, will require recommissioning. Those that have remained in normal use or where flushing has approximated normal usage (evidenced) may still require additional control measures.
  • Recommissioning a building water system should be appropriate for the risk. For very simple buildings flushing alone may be sufficient but for most buildings some form of disinfection is likely to be needed. In the worst cases, repeat disinfection and extensive cleansing flushing may be required to clear contamination.

A Flow Chart has been created by the LCA to be used in the risk assessment process and is available by clicking on the following link:


Feedback from Legionella Risk Assessments undertaken during the COVID-19 Pandemic

The below provides feedback from the dozens of risk assessments and audits completed since the Covid-19 lockdown period and refreshes the key elements.

During the Covid-19 low occupancy period it is critical that we follow the ACOP and Technical Guidance from the HSE and LCA, regarding the management of low occupancy in commercial buildings to:

  • Protect those who remain within the buildings and use the water systems from Legionella exposure. (For example, Security, Maintenance and Soft Services Personnel, plus small numbers of Tenant staff still using office space and services).
  • Avoid having to disinfect and sample water systems prior to full building re-occupation, which will inevitably be disruptive and may cause delays in re-occupation.

Hot and Cold Water Systems

Low Occupancy

Hot and cold water systems in buildings that are empty or with under-occupancy must address the issue of stagnation:

  • If the building is still partially in use take additional measures to keep the remaining occupants safe:
  • Flush to simulate use – weekly flushing may not be sufficient. (See Hygiene Flushing below)
  • Monitor temperature to ensure thermal gain in cold water is controlled.

Feedback from Risk Assessments conducted so far

In most instances low use outlet flushing has been instigated, however those carrying out the flushing were not carrying out and/or recording correctly.

For example, one line in the flushing log indicating ‘all communal outlets’ flushed for unspecified time with no record of temperatures does not follow the guidance.

Why do we require temperature recording during low use outlet flushing?

  • To demonstrate thermal control, i.e. Hot Water > 50°C and Cold Water < 20°C.
  • Without this it is impossible to determine whether the outlet has been flushed for the correct period (i.e. comparable to supply water), in which case the flushing period maybe too short (resulting in water stagnation hazards/thermal gain issues) or too long, resulting in Hot Water Vessels dropping below required storage temperatures.
  • Outlets within tenanted areas are not being flushed by the Managing Agents M&E contractor. In some circumstances the risk from this is low-medium (i.e. some offices only have a kitchen with POU water heater on each floor), in others the risk is much higher as there are toilets and showers within the tenanted areas, which form a significant part of the building’s water system. Our feedback so far is that there are few additional flushing measures being taken by tenants’ service providers.

Hygiene Flushing of Hot and Cold Water Systems

  • All outlets which are not in regular use (generally taps and showers) should be subject to a minimum of weekly flushing. This will need to include Landlord and Tenant services.
  • This procedure must be sustained and logged.
  • All infrequently used equipment within a water system (i.e. not used for a period equal to or greater than seven days) should be included on the flushing regime.
  • Flush the outlets until the temperature at the outlet stabilises and is comparable to supply water; Cold Water Service: within 2°C of the CWS Tank nearest outlet and < 20° Hot Water Service: >50°C or < 20°C if no longer heated. (Note keep circulating pumps running).
  • If thermometer equipment is unavailable then flushing outlets for 5 minutes is recommended, however recording temperatures is preferable to demonstrate compliance.
  • Toilet cisterns should just be flushed once a week, as should urinals.
  • Where the hot and cold water is not used for a prolonged period and has not been flushed as recommended. For example, this could be as little as two or three weeks, but will depend on the ambient temperature, condition of the water system, potential for exposure to aerosols and the susceptibility of users considered in a specific risk assessment. Hot and cold water services should be cleaned, flushed and disinfected, as specified in PD855864.

Evaporative cooling systems (Cooling towers and evaporative condensers)

Evaporative cooling systems should be maintained as usual or switched off and there is no leeway on this.

Evaporative cooling systems should already have robust start-up and shut-down procedures in place and the expectation is that these will be followed.

Feedback from Risk Assessments conducted so far:

 Unsurprisingly, cooling demands are much reduced which will affect the Cooling Tower operation in different ways depending on how these are set to operate, generally through the BMS.


  • You will need to update the system operation details in the logbook to reflect the reduced circulation pump and fan times during the Covid-19 low occupancy period.

The updated system operation details need to confirm arrangements are in place to ensure that treated water circulates through the entire system (this should be monitored, and records kept as normal). The system, including the fans, should run for long enough to distribute the treated water thoroughly.

 At Quantum Compliance we continue to monitor government advice regarding the Coronavirus pandemic, and we will update our guidance as necessary. During any periods of restricted travel, we will remain contactable to advise and assist.

If you require further information or advice regarding legionella control or have concerns specific to maintaining the risks associated with legionella bacteria during the coronavirus pandemic, please contact our Principal Water Consultant, Tom de Ronde, tom.deronde@qcompliance.co.uk

Water Services – Building Re-Occupation and Using Legionella Sampling & PCR Analysis.

What is the Issue?

Re-occupation of buildings following Covid-19 low occupancy or mothballing will need to involve validation Legionella sampling to demonstrate recommissioning measures have been effective.

The recommissioning process, involving cleansing flushing, system disinfection and validation sampling will potentially delay safe re-occupation of buildings.

How long will the validation sampling process take?

The standard for analysis of Legionella samples, involves a minimum 10 day laboratory incubation period. With the transport and administration time around the samples, this often means results are not available until 2 weeks after the sampling date.

High demand for laboratory services, when many buildings are attempting to safely re-occupy at the same time may cause the reporting times to increase further.

Is it possible to speed up the validation sampling process?

Yes and No.

A number of organisations, including the Legionella Control Association (LCA), have reminded the industry of the option that PCR analysis represents.

What is PCR analysis?

This is a rapid technique with results available to labs within 48 hours.

PCR is more specific than culture methods and will detect Viable but Not Culturable (VBNC) cells.

The analysis is significantly more expensive than standard Legionella culture.

Results are expressed in Genomic Units/Litre (GU/L), which cannot be directly compared against the HSE’s action thresholds, as these are based on Colony Forming Units/Litre (CFU/L).

If all PCR results are negative, then that will often be sufficient for validation purposes.

If there are any positive PCR results, then follow on actions can be difficult to justify until standard culture results are available – undermining the need to save time.

Therefore, carrying out standard Legionella culture, as well as PCR analysis, (i.e. double sampling each outlet) is recommended.


For any further advice, please contact:

Tom de Ronde

Principal Legionella Consultant / Water Team Leader

Quantum Compliance

M 07887 731912

E tom.deronde@qcompliance.co.uk

Fire Drills & COVID-19


The Covid-19 pandemic continues to present a range of challenges for Property Managers.  The following question is the latest raised by a number of clients as they continue their planning to re-occupy / increase the number of people permitted to restart work activities in commercials properties:

Should I still be carrying out fire drills in my commercial premises?

In answering this question, we initially turned to the National Fire Chiefs Council (NFCC) guide – COVID-19 Protection Fire Safety FAQs For Businesses which was published on 9th April 2020. Whilst the NFCC re-stressed the important part fire drills play in any successful emergency evacuation procedure, their advice focuses on assessing the current situation on an individual basis. Their advice also suggested alternative ways of familiarising new occupants with the premises including exploring the feasibility of running desktop fire drills.

Since the publication of this information and as more Government guidance has been published, in particular,  Working safely during COVID-19 in offices and contact centres – Guidance for employers, employees and the self-employed, dated 11th May 2020, it is clear that the practicalities of implementing social distancing rules, have led some fire authorities to now advise that fire drills should be postponed in the short/medium term – a stance which we would also support.

However, we also think that if the ‘responsible person’ (as defined by the Regulatory Reform (Fire Safety) Order 2005) simply declares a postponement to running planned fire drills, then this will not be sufficient in terms of complying with current requirements to have adopted a risk-based approach to introducing such changes.

Therefore, we are recommending that clients ensure occupants understand what action to take in the event of fire during the period when planned fire drills are not taking place. This process may include additional communication methods such as using noticeboards or emailing out procedures and evacuation plans. We are also recommending that it is important to review these against any layout alterations including changes to the use of entrance and exit doors, which may have been introduced as part of a more general COVID-19 Risk Assessments completed as part of re-occupation planning and the introduction of social distancing controls.

 How We Can Help?

For clients wishing to check that their existing emergency evacuation procedures are satisfactory, Quantum Compliance is able to undertake desktop fire drills which will involve a site review of:

  • the fire evacuation plan taking account of changes in occupation;
  • the arrangements for training fire wardens;
  • methods of communicating the fire evacuation plan;
  • Personal Emergency Evacuation Plan (PEEP) arrangements;
  • impacts on the property’s current fire risk assessment; and
  • testing and maintenance arrangements for fire alarm and control systems.

If you require further information or advice regarding any aspects of maintaining effective fire safety controls during the Covid-19 pandemic, please contact phil.jones@qcompliance.co.uk at Quantum Compliance.

Covid-19 Risk Assessment

COVID-19 Risk Assessment


It is now clear that COVID-19 will be with us for quite some time and the only way we will be able to completely remove the current restrictions on movements will be the development and production of an effective vaccine.  However, businesses are keen to get their people back to work but only in compliance with Government guidance and ultimately, in compliance with current health and safety law.

Furthermore, whilst it is important to reduce the risk of infection to tolerable levels, companies must also appreciate employee anxieties about a safe return to work and to make plans that accommodate workforce demographics and individual vulnerabilities, including age, pregnancy, mental health and relevant illnesses.  It is important to understand current employee attitudes to returning to work, including individual commuting options and even whether your employees’ household members have vulnerabilities or are shielding.

Health and Safety Criminal Law Obligations

As always, the starting point is to comply with the obligations in Sections 2 and 3 of the Health and Safety at Work Act 1974 – all reasonably practicable steps must be taken so as to ensure the health, safety and welfare of your workers and anyone else impacted by your operations. This includes keeping up to date with the work-related risks posed by COVID-19, as well as planning and implementing all reasonably practicable risk reduction measures.

More specifically, there is the requirement in Regulation 3 of the Management of Health and Safety at Work Regulations 1999 to make ‘suitable and sufficient’ risk assessments of the health and safety risks faced by your employees, as well as non-employees who are affected by your operations. Risk assessments must be in writing if you have 5 or more employees; and they must be reviewed or updated when the circumstances change. Circumstances and knowledge about COVID-19 risks are changing fast, so you need to keep abreast of the latest developments and act accordingly.

Our Approach

Our approach will be to visit the property / business operation and conduct a comprehensive assessment of the virus transmission risk associated with the following:

No.Hazard Subject
1Re-Occupation Planning
2Travelling To The Workplace, Arrival And Departure
3Workplace Design And Layout
4Plant And Equipment
5Security And Deliveries
6Fire Detection and Alarm Systems
7Employee Support Arrangements

 Against a comprehensive set of control standards, our consultants will offer pragmatic and practical virus transmission control advice in a clearly set out action plan.

Report Format

The specific report format of the COVID-19 Risk Assessment would include the following:

Section 1Executive Summary
Section 2COVID-19 Action Plan
Section 3COVID-19 Risk Assessment
Section 4Supporting Photographs
Section 5Protocol and Disclaimer / Limit of Advice

Evaluating Risk

The report will be prepared following the inspection of the property and will detail the control measures required to maintain social distancing rules thus reducing the risk of virus transmission. The control measures will be based on the interpretation of the most recent Government Guidance:

Working safely during COVID-19 in offices and contact centres

Guidance for employers, employees and the self-employed 11 May 2020

Available at:


This document will be updated over time. You can check for updates at www.gov.uk/workingsafely.

The scope of the report is limited to the areas specified in Section 1 above.

Unlike more commonly encountered hazards and the risks presented by them, which is determined by a process of reviewing existing control measures and identifying additional control measures, this COVID-19 risk assessment focuses on a single issue, namely, the transmission of coronavirus in the workplace. Furthermore, the more commonly used risk evaluation process is of limited use as is the prioritisation of actions required to reduce the risk.

Therefore, the residual risk for each of the hazard subjects in Section 3 has been deemed to be Tolerable once the identified actions detailed in Section 2 have been introduced.

Once the actions have been introduced and the risk of virus transmission is therefore, Tolerable, the client can re-occupy their building and commence (full or in part) business activities.