Yep, I managed to kill my TD5 in a deep urban ford in Hall Green, Birmingham
www.wetroads.co.uk, a couple of years ago after some heavy rain.
The depth guage said 3ft but the water managed to flow over the bonnet right to left at about the height of the tax disc completely submerging the bonnet by a couple of inches and the water came about half way up the drivers window!!!
Luckilly the ford is not very long and the car chugged outa the otherside. but the engine died accompanied with it's little light on the dash
The air filter was bone dry, so no water had got into the engine!
It was the current flow of the river that killed it. The ECU is in the battery box over the wheelarch and the force of the water against the right side of the car/wheelarch filled the battery box and the ECU with mucky river water and cause the engine to chug to a halt. After the RAC man had sucked his teath and recovered me home. The ECU was left on the radiator in the house for three days before it fired back up!
The ECU had now been sealed with silione, but I wont wade my TD5 anymore even though its done many a trip down Strata Florida with water flowing over it's bonnet....Well... maybe once more for luck!!!