Really good post.
There are some really cool water treatment solutions about. Graphene never ceases to amaze. It would be interesting to see the lifespan of the mesh and the costs. Does an electrical charge get involved?
Reverse osmosis is usually needed to get to 'potable' grade and is expensive in terms of energy. Where these things get sexy is when they interact with other technologies such as bio-organic systems which fix and absorb the undesirable inclusions and then self-eliminate. Has been a great servant of mining, chemical production (esp paints and dyes) - they can even treat cyanide!