Physical filtration at 0.5 micron, fine enough to remove cysts like
Cryptosporidium, which survive chlorination, and which are episodically
present in NYC municipal water. (Cysts are considered health – or even
life-threatening to those with weakened immune systems – people who are
HIV, pregnant, elderly, receiving chemotherapy, etc.) Reduces particulates
and general turbidity to virtually an undetectable level. New York
City water is typically close to the EPA’s maximum
contaminant level (mcl) for turbidity, due to a significant
count of particulates at the single-digit micron level.
Chemical filtration through activated carbon and other media
that remove chlorine and THMs (trihalomethanes, a byproduct of
the interaction of chlorine with organic material in the water), as well as
VOCs (volatile organic chemicals including MTBEs), metals and other
contaminants, including asbestos and copepods.