Here ya go, Guys! The engine in this 1931 west-looking photo is at the north end of the passenger platform, The foreground street is (present-day) US 231. So the tank was across the tracks from the depot, as Rick has portrayed it. Note there is not any Monon lettering on the tank, at least not in 1931.
And if you're going to have the water tank, don't forget the plug! See the second, 1946 photo, also of a northbound, arriving at the south end of the platform. If there was only one plug, I suspect the tank would have been adjacent to it, just out of sight to the right of this shot.