The product of choice IMO to build fiberglass water tanks is WEST System. And the Gougeon Bros have done all KINDS of testing with their products, and are eager to share the results with potential customers. If their book is not available to you, I''d enourage you to call them (see product literature for a phone number) and discuss what they think.
I would expect WEST system epoxy to instill no foul taste to the water, but better that you hear it from them...
Jack