An aluminum tank will be attacked by any chlorine in the water, plus
you 'really' need to install a magnesium removeable anode.

The chlorine attack will prevent you from chlore shock sanitization
and/or keeping a small concentration of chlorine to keep down the
growth of fungals and bacteria.

The BEST probable solution is to use aluminum (with baffles) and then
put an FDA/NSF approved 'lining epoxy' on the inside to render the tank
safe for chlorination, etc. Such lining epoxied can be applied with a
roller and brush (after sanding, etc. to make the aluminum 'bright').
Youll want: rated for POTABLE water and has the FDA/NSF
'certifications'; if you use 'common' epoxy you will get a high
concentration of 'leachables' in the water. This stuff is pretty
easy to 'roll-on'.
Do websearch for NSP-120 or go to the 'commercial' division of Interlux.
Such tank 'lining' in the marine and transportation industry is quite
common.
The advantage of lining a metal tank is that the tanki can have BAFFLES
which is impossible with a roto-molded 'plastic' tank.