Do we know for sure that casks of water were left for future castaways by the Norwich City crew? I thought that I had read this somewhere but I cannot recall where.
I have wondered about the 1940 report from Gallagher where he reports finding “corks with brass chains” thought to have come from a “small cask". These were found with the bones on Gardner. It is interesting that there were multiple chains and corks implying that there were multiple casks since you would probably not require multiple corks for a single cask.
See
Volume 15, 1999 pp. 42 – 50, Part 2.
This suggest that if maybe the bones were AE, then she must have found casks on the island since they were not probably packing casks of water on the Electra. I would venture to guess that if any water was carried by AE and FN this would have been in glass bottles or a perhaps a canteen of some sort. It also would seem that the quantity of water carried would be only for satisfying their thirst for the 20 hour trip and was not part of a "survival kit".