See also:

Driving through water
If driving through deep or standing water is unavoidable, proceed very slowly. Never drive through water that is higher than the bottom of the wheel rims (for cars) or the bottom of the hubs ...

Underbody
Flush the complete underside of your vehicle frequently. Keep body and door drain holes free from packed dirt. ...

Brake fluid
The fluid level will drop slowly as the brakes wear, and will rise when the brake components are replaced. Fluid levels between the MIN and MAX lines are within the normal operating range; ...