I live on a farm and catch rainwater. So (pesticides, solvents, pharmaceuticals, chlorine, flouride) aren't much concern to me. I'm more concerned with (grit, leaf litter debris, algae, bacteria). To that end I have two filters. The outer filter is 20nm pleated. The inner filter is 1nm dense mesh.

When I had my water tank cleaned and they refilled with chlorinated water, I swapped the inner filter for a 1nm carbon filter. But it's been swapped back now.

If I were to do it again, I don't think I would change it.