Portal: That natural refrigeration sounds good in case a person lives somewhere off the grid. I think on our farm before I was born they kept cans of milk in the spring-fed creek, the water was really cold but it was a good little walk from the house, at least it wouldn't spoil that way. I never thought of hanging a curtain in water and letting the air flow through to cool the house, that's almost like a water cooler if there is a good breeze.