A pressure regulator includes a housing having an inlet cap with an inlet flow passage and an outlet cap with an outlet flow passage. A plunger is reciprocally mounted in the housing. A stationary regulator valve seat is disposed between the inlet flow passage and an inlet to the plunger. A drain check shuttle is disposed in the inlet cap and positioned downstream of the regulator valve seat to prevent water from draining out of the regulator when an inlet water pressure is below a predetermined threshold.