Some years ago I purchased a leather costrel from a chap in the England. This was before I had heard of the Reverend. Anyway, the water in this costrel takes on a nasty sharp taste after a while. Normally I drink a lot of water when on a historical trek, & if it rains or I find a water supply then I can refill my costrel. Even so, I would like to know how to get rid of this foul taste in the water, so I have contacted the Reverend & am waiting on a reply. Meanwhile, I thought you might be interested in checking out a post on the Reverend's blog.
http://leatherworkingreverend.wordpress.com/2011/04/03/when-good-pitches-turn-bad/
My Leather costrel.
Two 1730ad costrels.
A late 17th century costrel.