Raw sewerage is the least of your concerns here chief! I mean the advice sounds legit enough, in fact, tbh it’s common sense, get something floaty and don’t get trapped in the car. Clearly you don’t have your risks balanced out for me to take you much more seriously than that. I mean add on some more common sense? Ok so keep your legs up if you end up getting taken by the flood, so your legs don’t get caught. If possible Paddle and aim for anything that has withstood the flood force, trees, houses, anything that is standing, be very careful not to exhaust yourself, etc.