If you’re a plumber with experience, you know what kind of revolution flexi hoses brought to the industry. They are fantastic for places where pipes can’t be installed, and are so convenient because of their flexibility. However, many are unaware of the dangers these hoses carry with themselves, especially if they are used for a long time and are not regularly maintained. Among the other dangers, one of the biggest is the legionella risk.
What are Flexible Hoses?
The flexi hose’s convenience happens because of the way it is built. Made from stainless steel with an inner lining of EPDM or other non-metallic materials, this braided connector is perfect for home positions where standard pipes can’t be installed.
If you look under your sink or in the bathroom, chances are great you’ll see these plumbing solutions. They fit perfectly in tight spaces, bend easily, and are not expensive, so everyone’s using them. Still, the interior degrades over time and exposes the risk of diseases.
The Overlooked Risk Inside Flexi Hoses
The internal environment of a flexible hose can be highly favourable to the growth of legionella bacteria. Stagnant water, fluctuating water temperatures between 20°C and 45°C, and degraded non-metallic materials provide ideal conditions for bacteria in water to multiply. Over time, the hose that is not WRAS approved, or has degraded, may pose a risk by allowing biofilm to form inside, creating a protective shield for bacteria that makes eradication difficult even with tank cleaning and disinfection.
Why Do Materials Matter?
The choice of material in a flexible hose is critical to water safety. EPDM is commonly used, but it is known to degrade under certain conditions, forming tiny cracks and fissures that harbour microbial growth. Non-metallic materials, when in prolonged contact with hot and cold water, may support the proliferation of bacteria. Hoses that are WRAS approved should be considered compliant and safer for water systems, but even these require regular monitoring to ensure they remain intact.
The Signs of Material Degradation
Hoses rarely fail overnight. The process is gradual, starting with small changes that many people miss. A bulge here, a soft spot there, or perhaps a patch of discolouration near a fitting. Sometimes the first sign is an odd smell when you run the tap, or a slick of slime forming at the connection. Each of these is a signal that the hose has started to degrade. Ignoring them means allowing bacteria to gain a stronger foothold inside the pipework.
What to Look for in Flexi Hoses?
Inspection is the simplest and most effective defence. A facilities team should make checking hoses part of routine water safety management. When the team sees signs of wear and tear, it’s time to replace them. Even without seeing issues, you should regularly change them because it costs little, but prevents serious issues.
Common warning signs include:
- Bulging, kinks, or soft spots in the hose.
- Discolouration or cracking near fittings.
- An unpleasant odour or visible slime around the connection.
Why are Flexible Hoses a Legionella Risk in Water Systems?
Flexible hoses pose a risk because of the way they interact with the wider water system. They often sit in awkward spots where water flow is reduced, and stagnation becomes more likely. When the temperature in those hoses sits in the danger zone between 20°C and 45°C, legionella bacteria can multiply rapidly. Every time the tap is turned on, contaminated droplets may be released, increasing the risk of legionnaires’ disease.
What does the guidance say?
The Health and Safety Executive’s Approved Code of Practice, better known as ACoP L8, makes the position clear. Flexible hoses are considered high risk unless they are WRAS approved, correctly maintained, and regularly replaced. Guidance suggests they should be swapped out every five to ten years—or sooner if wear is visible. Where possible, they should be avoided entirely, replaced with rigid pipework that removes the conditions in which bacteria thrive.
Legionella Risk Assessments and Pinpointing the Location of Flexible Hoses
A thorough Legionella risk assessment should always track down every flexible hose in the building. These small components are often tucked away under sinks or behind panels, making them easy to overlook. Yet one neglected hose can undermine an otherwise well-managed water safety plan. Expert water consultants know how to identify problem points, advise on remedial action, and ensure that every piece of the system is accounted for.
A Warning About Dead Legs
Dead legs are one of the most dangerous features in any hot and cold water system. They create stagnant pockets where bacteria multiply unchecked. A little-used tap attached to a flexible hose may act as a hidden dead leg, posing a serious risk of legionella proliferation. If a fitting is rarely used, it is better removed entirely rather than left to harbour stagnant water.
Biofilm and Bacteria – From Rubber Breakdown to Legionella Growth
When EPDM or other non-metallic hose linings begin to break down, tiny fragments provide food for microbial life. Soon a biofilm begins to form – a slimy coating that clings to the interior surface of the hose. This biofilm acts as a protective shield, giving bacteria the perfect hiding place from cleaning and disinfection. Once biofilm is established, it becomes extremely difficult to eradicate, allowing legionella and other pathogens to multiply unchecked.
Alternatives to Flexi Hoses
The safest alternative is still rigid pipework. It avoids the pitfalls of stagnation and biofilm formation and offers long-term reliability. If flexible hoses cannot be avoided, WRAS approved braided stainless steel hoses should be used. They offer better resilience and are designed to meet higher hygiene standards. Even then, they must be treated as a consumable component and replaced regularly.
Helpful Advice for Flexible Hoses
- Legionella Risk Assessment: Every hose in the system should be included in your risk assessment to spot hidden threats.
- Guidance: ACoP L8 and other water safety codes make it clear—hoses are high risk unless controlled.
- Length: Keep them as short as possible. The longer the hose, the greater the volume of stagnant water.
- Approval: Only WRAS approved hoses should be considered safe for potable water use.
- Healthcare: In healthcare settings, flexible hoses need to be avoided and outlets should be hard piped. Patients are more vulnerable, and water hygiene must be beyond reproach.
- Professional Help: Bring in expert water treatment providers to ensure your system remains compliant and your people protected.
Is Your Flexi Hose Putting You at Risk?
Flexible hoses may look like minor fittings, but they can carry major consequences. If ignored, they create an ideal environment for microbial growth, biofilm formation, and the growth of legionella. Asking whether your hose is safe is more than just good practice—it’s a question of workplace health and water safety. A simple replacement today could prevent a serious outbreak tomorrow.
FAQs
When should flexi hoses be replaced?
Flexible hoses should be replaced every five to ten years, but don’t wait if you notice any bulging, cracking, or discolouration. In practice, proactive replacement is always safer than stretching a hose to its limits.
Are Flexi hoses WRAS approved?
Some are, many are not. Only WRAS approved hoses are considered compliant for potable water systems, as they’ve been tested against strict standards for water hygiene and safety. If you are unsure, look and check, WRAS approved hoses are stamped and identified accordingly.
What are the three types of flexible hose?
Typically, you’ll come across braided stainless steel hoses with EPDM linings, all-plastic non-metallic hoses, and specialist WRAS approved designs for hot and cold water systems. Each type has different levels of resilience and risk.
Should flexible hoses be removed to reduce the Legionella risk?
Yes, wherever possible. Rigid pipework is always the safer option. If hoses must remain, they should be WRAS approved, properly maintained, and always included in the wider legionella control strategy.
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