Water

For a thirsty world:
Mostly large companies make water purification systems (ie GE, DuPont, Seimens)

Clorox makes Brita.
Pur water filters is a private company...

Zenon donates a good deal to Tsunami and others ... It's a Canadian company
ZEN.to

Pall Corp also makes heavy donations of water filters, and is the largest public company I have found so far
PLL
Pall has a solid balance sheet and some growth....