Flexible Braided Hoses: WRAS Approval, Legionella Risk and Replacement Intervals

Summary

Flexible braided hoses are one of the most common causes of water damage in UK properties. Insurance industry data consistently shows them as a leading source of escape-of-water claims, with failures occurring most often in hoses over five years old. A burst flexi hose under a kitchen sink or behind a toilet can discharge 400–600 litres per hour — enough to cause tens of thousands of pounds of structural damage within hours, often undetected overnight or over a weekend.

Despite this risk, flexible hoses are frequently left in place for decades. Many hoses installed in the 1990s and early 2000s remain in service with no inspection regime. The Legionella Advisory Committee's 2020 guidance recommends a 10-year maximum replacement interval, but the realistic safe service life in hard water areas or where hoses have been kinked or bent sharply is considerably shorter.

Tradespeople fitting new appliances, replacing taps, or carrying out bathroom refurbishments should always replace flexible hoses as part of the work — never reconnect old hoses to new fittings. This article covers WRAS approval requirements, failure modes, Legionella risk, and inspection protocols to help tradespeople advise customers correctly and protect themselves from liability.

Key Facts

• BS 6920 — the British Standard for suitability of non-metallic products for use with water intended for human consumption; all hoses must pass BS 6920 to be WRAS listed
• WRAS approval — Water Regulations Advisory Scheme; a WRAS mark confirms the hose will not leach harmful substances into potable water
• 10-year maximum — Legionella Advisory Committee recommended maximum service interval for flexible hoses
• 5-year practical interval — in hard water areas (above 200mg/l calcium carbonate), 5 years is a more prudent replacement schedule
• Fluid Category 3 — most domestic flexible hoses connecting to hot or cold potable water are Fluid Category 2 or 3 under WRAS; backflow protection must match the risk category
• Dead legs — any section of pipe/hose where water is not regularly circulated; Legionella bacteria multiply rapidly in warm water (20–45°C) in stagnant conditions
• Stainless steel braiding — the outer protective sleeve; corrosion of the braid is the most common visible failure sign; pitting and rust staining indicate imminent risk
• BSPT thread sizes — British Standard Pipe Taper; standard domestic flexi hose uses 1/2" BSPT (15mm compression equivalent) or 3/8" BSP for toilet cisterns
• Soft seat connections — hoses using rubber-seated connectors require correct torque (hand-tight plus 1/4 turn maximum with spanner); overtightening causes seat distortion and leaks
• Minimum bend radius — most flexible hoses specify a minimum bend radius of 3× the hose diameter; sharp kinks create stress concentration and early failure
• Insurance implications — many home insurers now exclude escape-of-water claims from hoses over 10 years old; document replacement dates for customers
• ACOP L8 — HSE Approved Code of Practice: Legionella — requires risk assessment and control measures for all water systems, including domestic settings with vulnerable occupants

Quick Reference Table

Detailed Guidance

WRAS Approval and BS 6920

All flexible hoses supplying potable water must be WRAS approved. This is not optional — it is required under Regulation 4 of the Water Supply (Water Fittings) Regulations 1999, which states that fittings must not cause contamination of water or waste of water.

BS 6920 testing subjects the hose material (inner tube, seals, and outer braid where relevant) to:

• Cytotoxicity tests — confirm materials do not support microbial growth
• Taste and odour tests — ensure no tainting of water in 24-hour contact
• Extractables — measure leachable substances at various temperatures
• Colour — confirm no discolouration of water in contact with the material

The WRAS approved products directory (searchable at wras.co.uk) lists compliant hoses by manufacturer and reference number. Always cross-check the WRAS number printed on the hose bag against the current directory — approvals expire and must be renewed.

What WRAS approval does NOT cover:

• Physical integrity (burst pressure, fatigue from repeated pressure cycling)
• Corrosion resistance of the braid (a separate consideration)
• Legionella risk from stagnation (this requires separate risk assessment)

Legionella Risk in Flexible Hoses

Legionella pneumophila, the bacterium responsible for Legionnaire's disease, multiplies rapidly at water temperatures between 20°C and 45°C. Flexible hoses in low-use areas — guest bathrooms, under-sink hoses on rarely-used taps — are particularly at risk because:

1. Water temperature in the zone 20–45°C is maintained by ambient room temperature or mixing of hot and cold in the hose body
2. The rubber inner tube of most flexi hoses provides a surface on which biofilm can develop — biofilm protects Legionella from chlorine disinfection
3. Dead legs — hose sections that dead-end at a closed valve — allow complete stagnation

HSE ACOP L8 (Legionella: The Control of Legionella Bacteria in Water Systems) requires:

• Risk assessment of all water systems, including domestic systems in premises with vulnerable people (care homes, private rented accommodation)
• Control measures including flushing rarely-used outlets weekly (30 seconds minimum, in a shower: 2 minutes)
• Documentation of inspection and flushing

For most owner-occupied dwellings, a full L8 risk assessment is not required, but the general duty of care under COSHH Regulations 2002 still applies. Tradespeople working in commercial premises, HMOs, and care settings must advise landlords of the flushing requirement.

Annual Inspection Checklist

Every flexible hose should be visually inspected at least annually. For landlords and facilities managers, document inspections in writing.

Inspection points:

Failure Modes

Understanding how flexible hoses fail helps identify at-risk installations:

Braid corrosion — the stainless steel outer braid is the primary structural element. In aggressive water conditions (high chloramine levels, soft water below 50mg/l hardness), the braid corrodes from the outside. Once the braid is compromised, the inner rubber tube has insufficient burst resistance. Failure is typically sudden and catastrophic.

Inner tube fatigue — EPDM or rubber inner tubes degrade from repeated pressure cycling and hot water exposure. After 10 years, micro-cracks can propagate rapidly, especially if the hose has been bent sharply.

Fitting corrosion — chrome-plated brass end fittings are vulnerable to dezincification (selective leaching of zinc from brass, leaving a porous copper structure). Dezincification resistance (DZR) brass must be specified for hoses in aggressive water areas (hardness under 150mg/l). DZR brass is stamped with a 'CR' or 'DZR' mark.

Over-tightening — the most common installation error. Rubber seat connectors require hand-tight plus a maximum quarter-turn with a spanner. Overtightening extrudes the rubber seat into the thread, distorting it and preventing proper seating. The fitting will weep immediately or fail within months.

Compatible Fittings and Thread Sizes

Always use PTFE tape (2–3 wraps) on male BSPT threads when using metal-to-metal cone connections. For rubber-seated connections (the most common type), do NOT use PTFE tape — the rubber seat provides the seal.

Insurance Implications

Major UK home insurers have updated their policies following the sharp rise in escape-of-water claims linked to flexible hoses. Key policy trends:

• Several insurers now explicitly state that claims arising from hoses over 10 years old may be declined on grounds of failure to maintain
• Tradespeople can protect customers and their own liability by providing a written record of hose replacement with date and installed product (WRAS number)
• The ABI (Association of British Insurers) recommends annual inspection and 10-year replacement — tradespeople who follow and document this guidance can demonstrate due diligence

Frequently Asked Questions

How do I know if a hose is WRAS approved?

Look for the WRAS mark on the product packaging or the hose itself. The mark includes a WRAS registration number. Verify this against the WRAS online directory (wras.co.uk/approved-products) — the registration may have expired even if the physical mark is present. Many cheap hoses sold through online marketplaces carry false WRAS claims; if in doubt, buy from a reputable UK plumbing merchant and ask for the certificate.

Can I reuse a flexible hose when replacing a tap?

No. Flexible hoses should never be reused after removal. Even if the hose looks undamaged, disconnecting and reconnecting stresses the end fittings and can disturb any corrosion products inside the braid. Always fit new WRAS-approved hoses when replacing taps, toilets, or appliances.

What is the correct torque for flexible hose fittings?

For rubber-seated connections (the most common domestic type): hand-tight plus a maximum of one-quarter turn with a spanner. There is no published torque figure (Nm) for rubber-seated hose connectors — the feel is the guide. If the fitting continues to rotate easily beyond hand-tight, stop. Overtightening is a more common cause of failure than undertightening.

Are flexi hoses in a commercial kitchen required to be replaced on a schedule?

Yes. Under HSE guidance for commercial premises, all water fittings including flexible hoses are subject to risk assessment under ACOP L8 and COSHH. Many commercial kitchens include flexible hoses in their annual service programme. BS 6173 (gas interlock systems) is not relevant to water hoses, but the general principle of scheduled maintenance for water fittings in food premises is reinforced by food hygiene regulation.

Do flexible hoses need to be isolated by a service valve?

Building Regulations Part G (Sanitation, Hot Water Safety and Water Efficiency) and WRAS guidance recommend that all permanent fittings should be serviceable without draining the system. A quarter-turn isolating service valve (15mm or 10mm as appropriate) should always be fitted on the supply side of each flexible hose, allowing removal without interrupting supply to the rest of the property.

Regulations & Standards

• Water Supply (Water Fittings) Regulations 1999 (SI 1999/1148) — requires all fittings in contact with potable water to be WRAS approved

• BS 6920:2014 — Suitability of non-metallic products for use with water for human consumption with regard to their effect on the quality of the water; primary WRAS testing standard

• HSE ACOP L8 (4th edition, 2013) — Approved Code of Practice: Legionella bacteria in water systems; covers risk assessment and control in all building types

• COSHH Regulations 2002 (SI 2002/2677) — Control of Substances Hazardous to Health; applies to Legionella risk management

• Building Regulations Part G — Sanitation, hot water safety and water efficiency; service and isolation requirements

• WRAS Approved Products Directory — Water Regulations Advisory Scheme

• HSE ACOP L8: Legionella — Health and Safety Executive

• Association of British Insurers: Escape of Water — guidance on water damage claims prevention

• CIPHE Guidance on Flexible Connectors — Chartered Institute of Plumbing and Heating Engineering

• pipe materials — copper and plastic pipe types and selection

• legionella risk — full L8 risk assessment guidance for landlords

• frost protection — protecting pipework from freezing damage