Connect Caravan onboard 3/4 BSP water fitting to 3/4" BSP parallel (G3/4 / BSPP)
How to join 3/4" BSP onboard and G3/4, and what stops it leaking.
These connect directly. Caravan onboard 3/4 BSP water fitting mates with 3/4" BSP parallel (G3/4 / BSPP) without an adapter.
A caravan onboard 3/4 BSP mains inlet is the same 3/4 BSP parallel thread as a garden or appliance fitting, so a standard 3/4 BSP connector screws straight on and seals on its washer. This lets a van inlet take a normal garden hose fitting for filling.
Use the regulated Watermaster or Ultraflow hook-up for pressurised mains, not a bare garden hose. Unregulated mains pressure can exceed the 1.8 bar the onboard system is designed for.
Related connections
Sources: Caravan water supply fittings, BSP thread sizes, Leisureshopdirect · Whale Watermaster caravan mains water connector (fits Watermaster + Truma Ultraflow) · ISO 228-1 (G / BSPP parallel pipe threads) · BSP thread dimensions chart (ISO 228 / ISO 7), AmesWeb · Washing-machine / dishwasher inlet 3/4 BSP connector data