With any water at or above the axle I would open the hub as some stage to check for any water damage as a precaution, during the floods I rode my bike several times through water up to 16" deep. Last week I gave the Norco a good service new drive train etc and a hub mini service, no water ingress so all was well. The axle entry I pack/syringe with white grease, not to be over looked is the brake rotor if fitted as some hubs don't have blind holes for the screws so they need sealing as well.
Generally with hubs you can get away with riding through deep water to an extent but isn't advisable without taking extra maintenance procedures, also the same applies to the mid drives like Bosch which also can suffer issues. None are designed for immersion but often it isn't under pressure or for long.