"'Mike'" wrote in
:

No way would I want to drink from my butt. Have you seen the wrigglies
in it? And the moss which comes off the roof?

I have tried filtering the water as it goes INTO the butt
........................... failed

Yes, I'm aware of the wrigglies etc. That's exactly what I'm concerned
about. I guess Jake's suggestion of filtering at the outlet is the answer.
I think one can make an effective filtration system out of sand and
charcoal, IIRC.

Al