Lister Bags? Looked like a duffle bag but had a liner that kept water from leaking out.
—”Lister Bags? “
We had those when I was in the Boy Scouts in, 1950s!
Everything we had was government surplus.
No liner! they were made from tightly woven cotton that would swell when wet and self-seal.
The idea was to maintain a thin film of water on the surface and provide some evaporative cooling.