While attempting to make a 14x14x14 cube of water by breaking ice inside a cobblestone box, source blocks generated by ice broken more than 7 blocks above the bottom would 'flow' into the source blocks below, disappearing. When broken into 7x7 (5x5 internal) cobblestone squares (plan view) starting at 8 blocks above bottom (blocks 1-7 is 14x14 water, blocks 8-14 are 5x5 water contained in 7x7 cobblestone squares, the source blocks would still flow down into the source blocks below.
While attempting to make a 14x14x14 cube of water by breaking ice inside a cobblestone box, source blocks generated by ice broken more than 7 blocks above the bottom would 'flow' into the source blocks below, disappearing. When broken into 7x7 (5x5 internal) cobblestone squares (plan view) starting at 8 blocks above bottom (blocks 1-7 is 14x14 water, blocks 8-14 are 5x5 water contained in 7x7 cobblestone squares, the source blocks would still flow down into the source blocks below.