Well, this was a interesting test, my grandparents used to sink a waterproof container in the big horse trough to help keep things like milk and butter cold in the heat summer. Most folks if they had access would use a cold house with a spring in it, and would put the jars or buckets etc into the spring house. Others yet would use a combo of a well or a root cellar to help keep things cool, and of course in a number of places, they would in fact cut and haul ice that was stored for summer cooling.
Well, I don’t have a spring, or dug into the side of a hill root cellar, I do have a well and cystern that I could try and see how they would work in pinch but wanted to start with something that more folks have, I started with a 55 gallon water drum as this is the typical size you will for a rain barrel in most folks yards.
Now I found it alot! harder to sink the plastic bucket then I felt it should have been, even with a few heavy rocks in it to be “food” and the temp gage in plastic to read when it came up, I finally had to sink it from both inside and outside, I tied a string to it so I had something to help pull on because suddenly that barrel was deep to get to the bottom off.
I didn’t think to take a photo of the outside temp (don’t know why but please trust me it was 31C at the time outside)
Not bad, close to ten degree’s cooler then the outside air but not better then my cellar in the house itself, which typically runs 15 to 18 degree’s cooler then outside.. Will try this again in the cystern as it goes even deeper into the ground then the cellar does and see what its reading will be.. Its cooler then outside but not good enough by any means.
Now if my back drilled well was pumped into a single trough, it would make a huge difference to the overall temp, I think because the water that comes up twice day is ice cold, raither then the barrel which just sits in the shade.
If you were without power(in all ways) what are you planning on doing to keep your food on short term base in the heat of summer, I figure you either cool it, or simmer it..cool it takes alot less effort if you can figure out how to make it happen in your neck of the woods, this would be one of those times that living very close by a lake or creek would be a great asset indeed.
Just another Day on the Farm 
the biggest difference between a rain barrel and a watering trough is that in the heat the animals drank so much more that the tank was constantly being filled with water from the well that was so cold your teeth hurt. Our tank was rectangular and the end closest to the house was boarded off
so there was access from outside. that way the animals couldn’t get to the end and the foodstuffs
couldn’t float away as dad had made shelves etc to hold things .I remember it as being huge,it probably was15 to 20 feet long and I do remember you could pump your hundred strokes and the llevel hardly rose at all. My uncle Ralph had a flowing well and ran the water through a barrel half for the house and kept food in gallon jars. That worked well also as long as the lids were on tight.
Every one had a system as well as the cellar as they werenot that cold in the middle of summer.
Women really learned to cook just the amount needed and to fill the rest of the meal with fruit,eggs,bread and huge salads out of the garden. A roast on Sunday became ground meat pie the next night and all meat would keep one day if not two once cooked, on the coolside of the house.Love mom
I wish I had paid more attention, but I wasn’t even ten when my Great Aunt died. But, I do remember that she kept things COLD in the spring house, suspended in a bucket down the well. It always smelled like the sweet earth and damp cedar and was so wonderfully cool, even on the hottest of days. Thanks so much to you and your Mom – I hadn’t thought of this in years! xo D
Today? Well, the best we can do here is basement temperature: no cistern or well, ice house or root cellar; but everything is alot cooler down there and a fairly stable temperature year round.