Flexible Tap Connectors: Sizes, Connection Types, and How to Choose the Right Hose

Flexible Tap Connectors: Sizes, Fittings, and How to Choose the Right Hose

Flexible tap connectors — also called tap tails, flexi hoses, or flexible hoses — are one of the most frequently replaced plumbing components in domestic and commercial properties. They connect the hot and cold water supply pipes (via isolation valves) to the inlet tails of taps, mixers, kitchen taps, basin taps, shower valves, and appliances. Choosing the correct length, connection type, and pressure rating prevents leaks and premature failure.

What Flexible Connectors Are Used For

The flexible hose solves a practical installation problem: the supply pipework from the wall or floor and the tap inlet tails rarely align perfectly. The hose bridges misalignment, absorbs minor vibration, and allows easy disconnection of taps for replacement without disturbing the supply pipework. Common applications:

• Kitchen mixer taps (under-counter hot and cold supply)
• Bathroom basin taps and pillar taps
• Bath taps and bath/shower mixer valves
• Toilet cistern fill valves (single hose, cold supply only)
• Washing machines and dishwashers (appliance-specific hoses with machine thread connections)
• Combi boiler filling loops (braided hose with ¾" BSP hose unions)

Construction: Braided vs Non-Braided

Flexible connectors are available in two main constructions:

• Stainless steel braided hose: A flexible inner tube (typically EPDM rubber or PTFE) enclosed in a stainless steel braid outer. The braid provides mechanical protection and significantly increases burst pressure resistance. Braided hoses are the standard specification for all plumbing applications in the UK — they are much more reliable than unbraided plastic hoses. Always specify braided hose for domestic and commercial water supply connections.
• Unbraided plastic hose: A plain flexible plastic tube without the outer braid. Lower cost but significantly more prone to UV degradation, cracking under sustained pressure, and catastrophic failure — these are responsible for a disproportionate share of domestic water leak insurance claims. Unbraided connectors have a much shorter service life and should be avoided in water supply applications.

Replacement interval: Even good-quality braided connectors degrade over time. Industry guidance recommends replacing flexible hoses every 10 years as a precautionary measure, or sooner if any signs of corrosion, kinking, or wear are visible. The inner tube of a braided hose is not visible — deterioration occurs internally before any external sign is apparent.

Connection Types

The two ends of a flexible tap connector typically use different fittings:

• Tap tail end (female ½" BSP): The upper end connects to the tap inlet tail. Most UK domestic taps have a ½" BSP male thread on their inlet tail. The hose has a female ½" BSP nut (often with a flat fibre washer inside) that threads onto the tap tail. Some mixer taps use M10 metric threads on their inlet tails — these require M10 connectors, not standard ½" BSP. Check the tap specification before ordering.
• Supply pipe end (various): The lower end connects to the isolation valve or supply pipework. Common options:
  • ½" BSP male straight or swivel — threads into a female BSP isolation valve outlet
  • 15mm compression olive fitting — connects to a 15mm copper pipe end or inline with a compression isolation valve
  • ¾" BSP — for bath taps and mixing valves with larger bore inlets

Swivel-end hoses (where the lower fitting can rotate relative to the hose body) are considerably easier to install in confined spaces — the hose can be tightened without needing to rotate the entire hose. Specify swivel-end hoses wherever possible for undersink installations.

Lengths

Standard flexi connector lengths for tap installation in the UK:

• 300mm: Close-coupled installations — the supply pipe is directly below the tap and there is minimal offset. Common for pedestal basin taps where the pipe comes up through the pedestal.
• 450mm: The most common all-round length — covers most under-sink and under-basin installations with a reasonable amount of reach and routing flexibility.
• 500mm: Useful where the isolation valve is further from the tap than usual, or where the hose must route around cabinet furniture.
• 600mm: Extended reach — for installations where the supply is unusually far from the tap, or where the hose must loop to absorb movement.

Do not overstretch a connector — a hose under tension is at greater risk of fitting fatigue and failure. Allow a gentle curve in the hose rather than a straight pull. Equally, do not allow excessive coiling — a tightly looped hose restricts flow and may kink internally.

Pressure Rating

Braided flexible connectors are typically rated to 10 bar (PN10) working pressure. UK mains water pressure is typically 2–6 bar in domestic properties (check with a pressure gauge — the PRV in the property, if fitted, limits incoming pressure to 1.5–3 bar). Central heating system pressure is typically 1–2.5 bar. Standard PN10 braided hoses are adequate for all domestic cold water, hot water, and heating connections within these pressure ranges.

For commercial and industrial applications where pressures exceed 10 bar, specify hoses rated to PN16 or higher, and confirm the inner tube material is compatible with the service temperature.

Hoses for Specific Applications

Washing Machine and Dishwasher Hoses

Appliance supply hoses connect the cold (and in some cases hot) water supply to the washing machine or dishwasher inlet valve. Appliance hoses use a ¾" BSP garden hose thread on the machine end (a different thread from the ½" BSP tap tail thread) — do not substitute a tap connector for an appliance hose. Appliance hoses are typically supplied with the machine but replacement hoses are available. Install the aquastop valve (pressure-responsive shutoff) type where the machine is in a room above other living areas — aquastop hoses shut off automatically if the outer sheath is breached, preventing catastrophic flooding.

Toilet Cistern Fill Valves

Toilet cistern fill valves connect to the cold water supply via a single ½" BSP hose, typically 300–450mm in length. The fill valve inlet is usually ½" BSP female or has a push-fit plastic coupling — check the valve type. Replace cistern fill hoses at the same time as replacing the fill valve.

Boiler Filling Loops

Boiler filling loops connect the cold mains supply to the central heating system to pressurise a sealed system. The standard connection is a ¾" BSP double-check-valve braided hose approximately 450–600mm long, connected between the cold supply and the heating system via ¾" isolation valves. The loop must be disconnected from the cold supply once the system has been filled — a permanently connected filling loop creates a cross-connection between the mains and the heating circuit, which is a Water Regulations breach. Many modern combi boilers have an internal filling loop built in, eliminating the need for an external hose.

Installation Best Practice

• Always fit a new hose when replacing a tap — do not reuse the existing hose, regardless of its apparent condition. The marginal cost is trivial versus the flood risk of a degraded inner tube.
• Use PTFE tape on all male BSP threads before making connections. Do not use hemp and jointing compound on hose end fittings — the compound can damage the hose inner tube and the fibre washer seat.
• Tighten hand-tight plus approximately a quarter to half turn with a spanner. Over-tightening crushes the fibre washer and can crack the hose end fitting body — particularly on plastic-bodied connectors.
• After installation, turn on the supply slowly and check all connections for drips before replacing under-sink furniture panels.
• Install with a visible route where possible so that any future leak is noticed early. Where hoses are concealed behind panels, ensure access hatches are provided.

Flexible Tap Connectors at APM Plumbing & Electrical

APM stocks braided stainless steel flexible tap connectors in all standard lengths (300mm, 450mm, 500mm, 600mm) with ½" BSP and ¾" BSP connections, in both straight and swivel-end configurations. Also available: washing machine hoses (standard and aquastop), toilet cistern hoses, and boiler filling loop hoses. Individual and multi-pack quantities available for trade customers.

Browse our flexible tap connectors and hoses or contact the Acton trade counter. Trade orders placed before 2pm ship same day.

Products Available from APM Plumbing & Electrical

Key flexible tap connectors available for trade collection or delivery:

Get It from APM Electricals

APM Electricals, 24 Western Avenue, Acton, London W3 7TZ. Call 020 8702 8080 or visit www.apmi.uk for same-day trade counter collection and next-day delivery across London and the UK.