"since Oct. 15, 2009, no company is allowed to manufacture, distribute, ship or sell any products that leach arsenic in concentrations greater than 5 parts per billion (ppb)" [1]
And bacteria growth is solved by following the manufacturer's directions. For example, Brita filters in use need to be kept in the fridge and changed every 2 or 3 months.
I assume this is true for 1) filters that are NSF certified and 2) wish to not display a prop 65 warning.
A majority of the water filters purchased on Amazon are not NSF certified and ship with a prop 65 warning. In fact, it's difficult to purchase water filter components that do not have a prop 65 warning.
The problem is that there's really not much to do. It's like when we had leaded gasoline. "What should I do about it?" Well you should go back in time and destroy the company that chose TEL over a more expensive but not lead based alternative, but nobody can do that.
What you do now is have the government punish the people who did this to us for money, and prevent this in the future. Some things can't be reversed or counteracted down the line.
Ymmv and you need to do your own research on specific chemicals of concern but I end up installing a reverse osmosis filter for tap water whoever I live now. It not 100% but from what I saw on the chemicals I was concerned about it did drastically reduce the issues.
I started doing this long ago when I lived in the Bay Area. So many super fund or near super fund sites that I was concerned about the water pollution.
A common household reverse osmosis filter would greatly reduce PFAS concentrations in drinking water in general. However, some PFAS may be small enough to slip through some RO filters, so it kind of depends.
Some plan for what to do in response would be…very helpful.