I think the freezer just died.
But, let's look at what you are doing.
You are using 7 'big bottles' of water a day. How big is big? Quart size? Gallon size? 1/2 gallon?
Takes a lot of energy to freeze water - change it from a liquid to a solid. Doesn't take much energy to cool water - but a lot to freeze it.
So, if your freezer is going to convert 4 or sogallons of water every day all summer, it will have to do more work. This is not frozen water stored in a freezer as some recommend - it is something that needs to be frozen every day.
That does take energy, and does take work by your freezer. So you are using it up a tad faster.
Myself, I don't think you are 'burning it up.' Just using it. Obviously, you are using it a little harder with the water freezing chore.
I'd think the outdoor location is harder on it. But in your house, it will be dumping all the heat from those water jugs into your house.... That wouldn't be cool either...
You have a tool - the freezer. You are using it. Tools wear out as you use them. The water freezing will wear it out a little quicker. Just how it is.
My opinion.
--->Paul