Evaporative cooler operable in a range of mounting angles

A reservoir for an evaporative cooler, the reservoir having a width and a floor and including:

• a first end and a second end opposite the first end, the first end being configured to be closer to an edge of a roof when the reservoir is mounted to the roof and the second end being configured to be closer to an apex of the roof when the reservoir is mounted to the roof;
• an outer wall, the outer wall including a first wall portion, a second wall portion opposite the first wall portion, a third wall portion extending between the first and second wall portions, and a fourth wall portion opposite the third wall portion and extending between the first and second wall portions, the first wall having a height that is greater than a height of the second wall portion, the first wall portion being at the first end of the reservoir and the second wall portion being at the second end of the reservoir;
• a water collection basin, having a width that is less than the width of the reservoir and a length, the water collection basin extending along the first end of the reservoir;
• a float valve assembly including a float valve housing having a longitudinal axis, a float valve, a lift arm pivotably coupled with a pivot coupling at a first end of the lift arm to the float valve, and a float coupled to a second end of the lift arm, the pivot coupling being offset from the longitudinal axis of the float valve housing in a direction away from the second end of the lift arm;
• a pump;
• and
• a drain valve,
• the water collection basin lying along an axis of rotation of the reservoir relative to horizontal and that extends longitudinally across the floor of the reservoir in the water collection basin and along the length of the water collection basin, the pump, the float, and the drain valve being within the water collection basin and horizontally aligned along the axis of rotation of the reservoir.