I remember when I was on anti parasites herbs I also asked the same question at related forums. But in most cases the answer was - ONE THING AT TIME. Body needs to concentrate on doing one thing. If u try to kill two birds with one stone then it could be too hard for ur body to deal with it. Yes, this was an answer in most cases but also I was suggested that it is OK to start ur fast one week before ur Humaworm is over.
If u want to go for a Water Fast then better be just on water otherwise what's the point to call it a water fast? U decide :)