Abstract: An insulating assembly is provided for animal waterers. The insulating assembly includes a large sheet of flexible, closed-cell foam material preferably at least as large as the largest top opening of an animal waterer with which the insulating assembly is to be used. The insulating sheet is cut to the shape of the opening of the waterer, but preferably slightly smaller so as to leave a gap between the edges of the sheet and the side walls of the waterer. An opening is cut in an intermediate portion of the insulating sheet through which water can enter from below the sheet for access to the animals when they push the insulating sheet down into the water with their noses. A plurality of weights are provided which are connected by lines to the sheet, preferably extending up through the sheet and washers thereabove and then being tied in knots. The lines are long enough so that the weights can rest on the bottom of the waterer when it contains water at the maximum level.