Water pressure regulator

A water pressure regulator is a small brass or plastic reducer that drops mains water pressure down to a safe 40–50 psi (2.7–3.4 bar) for a motorhome. It protects internal PEX plumbing and fixtures from bursting under high mains pressure.

Without a regulator, US mains can hit 80–150 psi and burst a PEX fitting or pop a tap within days. Basic non-adjustable units cost $10–20; premium adjustable models with a gauge (Valterra A01-1124VP, Camco 40058) cost $40–80. Fit it at the campsite tap, not the RV inlet. Drain and store dry for winter.