The ornamental design for an evaporativecoolingsystemwatercontainer, as shown and described.
FIG. 1 is a top, front, and right side perspective view of an evaporative cooling system water container showing my new design, the broken-line disclosure being understood to represent portions of the article in which the claimed design is embodied, but which forms no part of the claimed design;
FIG. 2 is an enlarged top, front, and right side perspective view thereof;
FIG. 3 is an enlarged front elevational view thereof;
FIG. 4 is an enlarged right side elevational view thereof;
FIG. 5 is an enlarged left side elevational view thereof;