all you are removing with filtration is plant matter.
actual “contaminants” such as pesticides or heavy metals won’t filter out.
What scale are you doing this on?
Personal or retail?
Black/Grey/Legal market?
Try it! Filter to 2.5u, then filter 1/2 of that to 0.45u. how much weight did you lose to the 0.45u filter? can you taste the difference?
Ask a stranger…by which I usually mean send it out for 3rd party analysis…although if you’re doing this for fun not profit, you could just invite others to help with your Organoleptics .