UK trade guideControls & Valves 3 min readUpdated 9 July 2026

How to Replace a Service Valve (UK)

Fit a 15 mm or 22 mm mini service (isolation) valve. Chrome, ball or straight. Kitchen and basin isolators.

PeglerRelianceJG Speedfit

Types

  • Screwdriver-slot compression — cheapest, hidden under sink.
  • Ball valve lever — best flow, more visible.
  • JG Speedfit — plastic push-fit, fast install.

Fit

Isolate mains. Cut pipe. Deburr. Compression olive with copper flow direction. Full ¼-turn beyond hand-tight.

Frequently asked questions

Do service valves reduce flow?
Slightly for slot-type (up to 20 %). Ball valves — negligible.
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