Legionella - stay vigilant on water hygiene

30th of November 2015
Legionella - stay vigilant on water hygiene
Legionella - stay vigilant on water hygiene

L8 guidance now has less emphasis on precisely when you should carry out some of the procedures that help to control and prevent Legionella.  But does that mean we can relax or ease up on legionella prevention?  Not at all; we need to be more vigilant than ever, as Gary Nicholls, managing drector of Swiftclean Building Services, explains in this exclusive article for ECJ.

The L8 Approved Code of Practice and guidance on Legionnaires’ disease, issued by the Health & Safety Executive (HSE) in the UK, guides duty holders, including employers; those in control of premises; and those with health and safety responsibilities for others to comply with their legal duty to protect building occupants from infection by legionella bacteria.

This Approved Code of Practice (ACOP) status makes legionella control an important legal duty. It is essential to prevent outbreaks of Legionnaire’s Disease, the flu-like illness which legionella causes, which can be fatal, particularly in the elderly or people suffering from underlying health conditions such as respiratory, lung and heart diseases, impaired immune system, etc.

This is why, if a nominated Responsible Person is deemed negligent in a legionella outbreak they and their organisation can be prosecuted under the Health and Safety at Work Act and COSHH Regulations. Limitless fines can be imposed on the organisation and custodial sentences can also be given to individuals who are deemed negligent, especially if a fatality has occurred.

The recent fourth edition of L8 guidance places greater emphasis on a number of important legionella control issues which now have ACOP status: risk assessment; the specific role of an appointed competent person, known as the Responsible Person; the control scheme; a review of control measures; and duties and responsibilities of those involved in the supply of water systems.

The first step towards L8 compliance is a comprehensive risk assessment, and this requires a thorough investigation into the configuration and condition of all water systems present at a site. Water should flow freely around the system and there should be no areas of the distribution pipework system where water can remain static and potentially stagnate.

At the design stage of any new system, this should automatically be a prime consideration, but it is also important to ensure that operational systems have not developed ‘dead legs’ over time - which can occur when pipework has been altered for instance during the removal of a shower or sink. If this alteration is not carefully considered with reference to legionella prevention, ‘dead end’ lengths of pipe in which water can ‘sit’ and stagnate can be created.

These provide favourable conditions for legionella bacteria proliferation, so any historic dead ends should be identified  and removed as fully as possible, to enable water to circulate through every part of the water system, eliminating static areas.

Careful design

New water systems should be carefully designed to avoid any static areas and services or outlets which are likely to become infrequently used. Where a water system or outlets have not been in use for a week or longer L8 requires periodic flushing of the water system to be carried out in order to avoid conditions favourable for the proliferation of legionella bacteria.

Cold water storage tanks in buildings are often situated on roof top spaces and installed in enclosures which can capture heat and raise the temperature of the stored water. This can be an issue especially in the warmer summer months when stored cold water can suffer from significant heat gain, and is normally as a result of the tank not receiving adequate demand. This scenario provides a perfect potential breeding ground for legionella.

Therefore it is essential that cold water storage tanks are not oversized, receive good turnover rates and they have adequate insulation installed. Water tanks need to be protected against significant heat gain during the summer, so existing tank installations should be reviewed to see if this is occurring. If necessary they should be retrofitted with shading or insulation to prevent the water temperature being raised by solar gain. New cold water tanks should be installed with solar shading or appropriate insulation.

Once an appropriately sized cold water tank is operational the storage temperatures need to be checked during the summer; and it should also be possible to drain the tank completely for cleaning. If the cold water system is not used for a shutdown period during the summer, this is also the optimum time to clean and disinfect it or to carry out any maintenance or refurbishment required.

Cold water tanks should be checked periodically, at least annually, to make sure that they are free of excessive sediment contamination, fungal growths, insects, and vermin such as pigeons and rats, etc. The structural condition of the tank should be checked for L8 compliance and if its interior is degraded it should be refurbished or replaced as necessary.

Buildings not in use

Properties which have shut down periods can be particularly prone to legionella proliferation as water may stay stationary while the building is not in use. Buildings such as factories and especially schools, colleges and universities, which have long breaks when buildings are not used, are more vulnerable than most. This also applies to buildings such as stadiums which are used seasonally; but any property, either domestic or commercial, which has been unoccupied for some weeks may also be vulnerable.

Since last year private landlords and letting agents must now tackle this important aspect of property management. When letting property to new tenants, it is now just as important to ensure that the water supply is clean and healthy as it is to ensure that the gas and electricity supplies are safe and that there is an energy performance certificate.

If a commercial property has a wet cooling system or cooling tower, L8 does still stipulate a minimum frequency for testing. Cooling towers and wet cooling systems should be tested at least quarterly for the presence of legionella bacteria; if found present, there should be immediate remedial action taken to eliminate it.

If a property has a history of the occurrence of legionella, L8 also requires more stringent measures. Where the control scheme has been found to be ineffective, for instance the temperature control regime cannot be achieved or in systems which have a history of legionella bacteria being detected, regular ongoing testing should be carried out to ensure legionella bacteria has not reoccurred.

Water should also be tested for the presence of legionella if the building has been unoccupied or the water system has not been used for several weeks, as during the long summer break in schools and colleges. Water services also need to be flushed through before use is resumed at the start of the new term. How this is conducted is also important - flushing should be carried out without creating water spray as legionella can be inhaled in fine water particles.

It is important, if possible, to conduct flushing before any cleaning teams enter the building. If this is not done and the cleaning team is the first to run showers and taps etc, they will be very vulnerable to inhaling contaminated spray and contracting Legionnaire’s Disease.

To comply with L8, there must be a current legionella risk assessment in place. This needs to be viewed as a living document which requires regular review to ensure that it remains appropriate. It must be updated if any significant changes are made to the systems. It is a legal requirement for a Responsible Person to be appointed, so care should be taken to ensure if roles or personnel change over time, there is still a Responsible Person and a current risk assessment in place.

Annual checks

To avoid any possibility of this being overlooked, it is a good idea to implement a robust legionella process of annual checks to ensure that nothing has changed with regard to the management structure or physically to the water system. An equally good idea is to make reviewing of L8 compliance part of an induction process whenever a new property manager or owner takes over.

If there is any aspect of legionella control which the Responsible Person is unsure of, it is wise to seek expert advice.  An expert can not only help you to formulate and correctly document a risk assessment, they can also provide training and help establish robust control processes such as routine testing and maintenance. The Responsible Person also needs to ensure that all routine monitoring and maintenance tasks involved in the legionella control regime are accurately documented within a site based logbook, to provide legal protection as well as legionella prevention.

Expert advice should also be sought before designing and installing a new system; starting out with an L8 compliant system and robust prevention processes is the best way to ensure that water stays legionella free in the future.



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