Welcome to CO
Is the garage heated, air conditioned, and/or insulated? If it is, then Garage can work great, but otherwise you will want to put it in the basement. Summers here are generally in the 90's-110 range for temps, and winters can generally around 30's but can dip well below freezing from time to time, so garage would need insulation, and the same heat/cooling as the house, if you don't want to spend a fortune heating, and cooling the tank throughout the year.