Item:
This tiny water skin barely holds enough water to put out a candle, but it
should quench your thirst long enough in an emergency. It is sewn of soft
rat hides and not adorned with any sort of accoutrements. It is truly
for survival only.

A small hide water skin is a drink container, made of hide, and weighs 4 pounds 12 ounces.
When you look inside, you see:
It's less than full of a clear liquid.

When buying this item, the keywords hide, water, and skin do not work. Only "small" works.

When drinking from this item, the keywords hide and small work, but water and skin do not.

When looking at this item, all four keywords work.

It is sold by a wandering merchant I found southeast of Tir-Talath. Not sure its usual location.

Hopefully the item will be more intuitive NCR.