Add the water to a small pot on your stove, sprinkle the gelatin over the water and stir over a low heat until completely melted. About 1-2 Minutes.
Add the pumpkin puree, condensed milk and pumpkin pie spice to a medium mixing bowl and beat until well mixed, about 1 minute.
Set aside ½ cup of the whipped topping and spoon the rest into the pumpkin mixture and stir well until combined.
Stir in the gelatin mixture and stir again. Allow to cool somewhat - although it shouldn’t be all that hot, then pour the pumpkin pie filling into the store-bought crust.
Place into the refrigerator for 4 hours or more, until completely set.
Use the remaining ½ cup whipped topping to serve the pie with. Add a dollop (or pipe it) right when serving and dust with a little pumpkin pie spice.