Flexible Tap Connectors: How to Choose the Right Size and Length

A flexible tap connector — sometimes called a braided hose or flexi hose — connects the tap tail to the supply pipework under the sink or basin. Every tap installation needs them. The challenge is that they come in half a dozen combinations of end fitting size, pipe diameter, and length, and choosing the wrong one means a second trip to the merchant. This guide covers the full Embrass Peerless range at APM and gives you a decision framework for getting it right first time.

The Three Measurements You Need Before Buying

A flexible tap connector has two ends. Before you order, identify:

1. The pipe size — the diameter of your supply pipework. Standard domestic plumbing uses 15mm copper. Older or commercial systems may use 22mm.
2. The tap tail thread size — the BSP (British Standard Pipe) thread on the tap tail. Measure or check the tap specification. The two standard sizes are ½" BSP (most modern taps) and ¾" BSP (mixer taps with larger tails, bath taps, and some kitchen mixers). Some continental and designer taps use 3/8" BSP.
3. The length needed — measured from the compression nut on the pipe to the tap tail. Allow for any offsets. Available lengths are 150mm, 300mm, 500mm, and 900mm.

The Full Range: 15mm Connections

15mm is the standard for virtually all domestic basin, bath, and kitchen tap supplies. The compression end fits directly onto 15mm copper or push-fit pipework.

½" BSP tap tail (the most common)

½" BSP is the standard tap tail thread on UK kitchen taps, basin taps, and most monobloc mixers.

• 15mm × ½" × 150mm — — for connections where the tap tail and pipe are very close together. Tight vanity units and wall-hung basins.
• 15mm × ½" × 300mm — — the default length. Fits the vast majority of standard kitchen sinks and pedestal basins where the pipe rises to within 30cm of the tap tail.
• 15mm × ½" × 500mm — — where the supply pipe enters at a lower point, vanity units with cabinet depth, or where the tap position makes a 300mm hose pull tight.
• 15mm × ½" × 900mm — — for unusual layouts: pipes entering from floor level, tall vanity units, or any installation where the hose needs to run around an obstacle.

¾" BSP tap tail

¾" BSP is used on bath taps (pillar and mixer), large kitchen mixer taps, and some commercial fittings.

• 15mm × ¾" × 150mm —
• 15mm × ¾" × 300mm —
• 15mm × ¾" × 500mm —
• 15mm × ¾" × 900mm —

3/8" BSP tap tail

3/8" BSP appears on some continental taps, older UK basin taps, and some designer ranges. Less common but worth knowing.

• 15mm × 3/8" × 300mm —

The Full Range: 22mm Connections

22mm compression connections are used on bath mixer taps with a 22mm supply, on higher-flow shower mixer valves, and on some commercial installations.

• 22mm × ¾" × 150mm —
• 22mm × ¾" × 500mm —
• 22mm × ¾" × 900mm —

Connectors with Built-In Isolation Valve

These combine a flexible hose and an isolation valve in one fitting — the compression nut connects to the pipe, the valve body is mid-hose, and the tap tail fitting is at the other end. Useful when retrofitting taps to existing pipework that has no isolation valve, or for tight spaces where fitting a separate iso valve and hose would be awkward.

• 15mm × ½" × 300mm with Iso Valve — — more than the standard hose, gives you isolation for future maintenance without a separate valve fitting.
• 15mm × ¾" × 300mm with Iso Valve —

WRAS-Approved Connectors for Monoblock Taps

Modern monobloc basin mixers and kitchen mixer taps often have M10 threaded tap tails — a metric thread, finer than BSP, used by most European tap manufacturers. These require a specific WRAS-approved connector, not a standard BSP flexi hose.

• MasterFlow Mono Basin Flexible Tap Connector, WRAS, M10 × ½" — — WRAS approved, suitable for mains-pressure systems. If you're fitting a modern basin mixer from any major European brand (Grohe, Hansgrohe, Bristan, Crosswater, Hudson Reed), this is the connector for the job.

Decision Guide: Which Connector for Which Tap?

Installation Notes

• Always use PTFE tape on the BSP thread at the tap tail end. One or two turns clockwise is enough. Over-wrapping on a fine thread strips it.
• Do not overtighten. Flexible connectors have a rubber or nylon washer at the tap tail end — hand-tight plus a quarter turn with a basin wrench is sufficient. Over-tightening splits the washer.
• Check the olive. The compression end uses an olive — ensure it is seated squarely before tightening. A skewed olive will leak immediately or fail within weeks.
• Check for kinks. After fitting, route the hose without sharp bends. A kinked braided hose restricts flow and fatigues the inner tube.
• Replace, don't patch. Flexible connectors that show corrosion on the braiding, any weeping at the end fittings, or are over 10–15 years old should be replaced. They are inexpensive insurance against a significant under-sink leak.

The full range is in stock at our Acton trade counter — buy per unit or in quantities for a full bathroom fit.

APM Plumbing & Electrical | 24 Western Avenue, Acton, London W3 7TZ | 020 8702 8080 | apmi.uk