What are flexible hoses and why would you use them?
Flexible hoses are typically made from braided stainless steel, lined with an EPDM (ethylene propylene diene monomer) rubber tube. They are versatile and often used in awkward spaces where rigid pipes would be difficult to install.
Non-metallic materials such as synthetic rubbers are often unsuitable for use with wholesome water, because they can support extensive microbial growth, impart an unpleasant taste or odour or release toxic substances to the drinking water. The leaching of chemicals can sometimes be used by bacteria as a nutrient source to promote growth.
What are the problems?
Due to the shape and position of the hose once installed, it can be easy for water sit inside the hose and become stagnant. It is important that flexible hoses are the correct length and are installed as directly as possible so as not to leave large loops or bends.
If the flexible hoses have been in place for several years, it is more likely that the interior of the pipe will have degraded to form tiny cracks and fissures in the surface. This process can provide both a nutrient source and safe harbour for Legionella and other bacteria. Ideally flexible hoses should be replaced every five to 10 years, but in practice, replacement may not happen until they leak.
As the rubber deteriorates, it can encourage the formation of biofilm which can coat the internal surface. This biofilm acts as a protective shield for bacteria, making it difficult to eradicate.
Are there any standards in place?
The Water Regulations Advisory Scheme (WRAS) sets strict standards for materials in contact with potable water. Any flexible hose that is not WRAS approved should be considered high risk. To safely manage flexible hoses, the following points should be considered:
- Make sure that flexible hoses are all WRAs approved.
- Flexible hoses should be the correct length and installed as direct as possible so as not to leave large loops or bends.
- Flexible hoses should be checked every two years for visible signs of wear:
- Bulging, kinks, or soft spots in the hose.
- Discolouration or cracking near fittings.
- An unpleasant odour or around the pipe or from the outlet it supplies.
- Visible slime around the connection.
- Leaking, either through the hose or at the connection points.
This guide is of a general nature; specific advice can be obtained from Assurity Consulting.
Assurity Consulting is the UK's leading independent compliance consultancy specialising in workplace health, safety and environmental solutions. We have over 35 years' experience of helping customers of all sizes, from across all sectors, manage their compliance responsibilities, making sure that their organisation is compliant, their employees are safe, their processes are cost effective and their management team is in control.