[gnorbury]

Maybe a dumb question, but have you checked the state of the plumbing? Flexible hoses are very susceptible to biological growth, and it can be extremely hard to clean out even with bleach.

The first season I had my boat it suffered from really cruddy tasting water. A quick investigation showed the cause to be the blackend & rather gungy "clear" pvc hoses rather than the stainless steel tanks.

Graham