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Legionella and Flexible Water Supply Hoses
Flexible hoses are frequently used in potable water systems to provide a convenient link between fixed pipework such as copper and the service to which it supplies (for example a tap or drinks vending machine etc). Often where access or space is an issue, the plumber will install a flexible hose which is normally synthetic rubber encased in a steel braid.
In 2007, Dr Tom Makin (previously Directorate Manager - Department of Medical Microbiology, now an independent consultant) reported that there was a significantly increased risk of legionella proliferation within a building water system that contained flexible hoses. It was believed at the time that the problem was limited to cheap imported products. During the extrusion process, ´hard‘ water had been used and this lead to microscopic deposition of limescale, causing pitting in the rubber surface. The pits provided an ideal micro-environment for the formation of biofilm and legionella growth.
The advice provided at the time was that building managers should ensure that their flexible hoses were WRAS (Water Regulations Advisory Scheme) approved and compliant with British Standards. Further research was conducted and early in 2010 it was subsequently reported that the WRAS approved hoses were equally susceptible to biofilm growth. EDPM (ethylene propylene diene monomer) materials were found to support heterotrophic bacteria including legionella and increase their growth tenfold. The Department of Health issued an Estates and Facilities alert in May 2010 (ref DH-2010-03) requiring that action be taken to assess the risk from flexible hoses.
Nemco have been reporting the presence of flexible hoses as part of the legionella risk assessment process since 2007 with a recommendation to check the standard of the product in use to ensure WRAS approval. Since June 2010, the advice in the risk assessment report has been changed to recommend removal (particularly in higher risk premises) and replacement with fixed copper.
As required by the approved code of practice for legionella, L8, building owners and managers should ensure that they review existing legionella risk assessments in light of the new guidance. The presence of flexible hoses should be noted in the report and added to the remedial action list for replacement. The work may be prioritised relative to risk with aerosol producing outlets being replaced initially, followed by lower risk outlets such as WC cisterns and drinks vending machines. High risk properties such as healthcare premises should take priority over all replacement schemes.
The flexible hoses wherever possible should be replaced with fixed copper or flexible polyethylene plastic piping. Where it is not practicable to replace a flexible hose, it should be ensured that the product is non EPDM and WRAS approved.
For more information please visit http://www.nemco-utilities.co.uk/
Contact Details :
Nemco Utilities Ltd
12 Kempson Way
Hillside Business Park
Bury St Edmunds
Suffolk
IP32 7EA
Telephone: 01284 724503
Fax No.: 01284 724826
Email: [email protected]
Website- http://www.nemco-utilities.co.uk
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