Recommissioning your water system

14 May 2020

Published in: Member News

This blog covers guidance on how you should recommission your water system before reopening your building

As per the guidance issued by the Legionella Control Association (LCA) 13th May, 2020, it is essential that when buildings reopen following the lifting of COVID-19 restrictions, that any water system is not simply put straight back into use. During the period of shutdown, if flushing cannot be carried out weekly or twice weekly dependant on the setting, it would be sensible to formulate a recommissioning plan for each water system to allow safe start-up, and assurance to users that it is safe and free of bacteria.

This article provides guidance to owners and managers of premises regarding recommissioning of their water systems after a period of shutdown. Now that the government is planning their steps to lift the lockdown in a phased manner, it is important that duty holders take necessary steps to make sure that their buildings are safe before they reopen.

The following points have been compiled by referring to various guidance released by, LCA, Public Health England, and the HSE in line with guidance documents including ACoP L8 and HSG 274.

Recommissioning of a building water system can utilise various levels of intervention, and the level of work and investment 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.

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

The minimum expectation for small, simple hot and cold-water systems would be flushing through with fresh mains water. Larger buildings, those with tanks, showers, calorifiers and more complex pipework the expectation is likely to be for more extensive flushing, followed by cleaning and disinfection. Additionally, temperature checks should be carried out to ensure that the system controls are within tolerance.

 During COVID-19 water systems should not be drained down - HSG274 does not advocate this.

Where buildings have been empty for a period of time and during warm weather, it is likely that some increase in bacteria levels and biofilm will occur.  These water systems may require more than a simple disinfection to be successful.  

In all cases where systems are being recommissioned, it is sensible to have evidence to prove/reassure that the recommissioning process has been effective.  Legionella sampling to BS7592 is recommended within recommissioning plans to validate the effectiveness of the process.

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. In addition to legionella risk, drinking water retained within buildings may no longer be potable following a period of prolonged stagnation.

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This is a basic guide to getting your water system back to normal, however each water system depending on its complexity may require additional work. Speak to your consultant for bespoke advice.

You should ensure that you have the following in place during and after the COVID19 crisis:

·       A documented risk assessment in place developed by persons who are experienced and competent.

·       Recommendations of the written scheme and risk assessment are implemented for the control of Legionella.

·       Regular flushing or treatment programmes based on equipment and manufacturer’s guidance are planned.

For more information:

LCA Guidance on reopening buildings 

LCA Guidance during COVID 19 

COVID 19 legionella guidance for dental surgeries 

HSE guidance for schools 

Want more bespoke advice and guidance? Speak to NANT's experts today!

01902636355 |

Submitted by Imran from Nant Ltd
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