Some drops just too rare?

[The Cid]

That would be because they drop from Nord Heavy Huscarls, rarely on wave 13 and/or 15, always wave 17 and 19.  I doubt you solo there often, if at all, and many groups fail to get that far as well.  In groups, there seems to be one or two Water of Hvergelmir drops a run, usually on wave 17. 

Keep in mind that this item is used in the very best craftables available.  I am pretty sure it is rare for a reason.

Last time I looked not a single water of H on auction hall, players are making wave 17 and 19 but not getting the drops?