14,00,000,000 B.C.E. The first molecules of water form in space after an early star explodes in a supernova (try filming that, Michael Bay.)
4,000,000,000 B.C.E. Liquid water on planet Earth–IN YOUR FACE, NEPTUNE AND MARS!
2000 B.C.E. Egyptians boil water and use crude sand and charcoal filters like, you know, Egyptians.
400 B.C.E. Hippocrates designs a sleeve-like cloth filter. He uses his "water cure" to treat many diseases but sadly does not cure his baldness.
500-1500 A.D. Beer is the staple beverage of Europeans because the fermentation process naturally purifies water and they need more excuses to day-drink.
1627 Sir Francis Bacon attempts seawater filtration. The resulting product is salty and undrinkable, much like seawater.
1660s Anton van Leeuwenhoek uses a microsope to discover tiny, living organisms in the water–cholerae, salmonella, and maybe these little guys. (On a side note OH MY GOSH DELICIOUS SHRIMPJUICE!)
1800 John Snow (not that one) discovers chlorine as a disinfectant. Happily, people stop dying of cholera and typhoid.*
1804 Paisley, Scotland installs the first municipal water filter plant. SLAINTE!
2012 Concerns about pesticide chemicals, industrial sludge, chlorine byproducts, and lead continue to motivate consumers to use water filters in their homes. Lots of people read the Fridge Filters Blog and get happy and smarter.
*Sadly, waterborne illnesses are still a major concern in many parts of the developing world. Please visit http://thewaterproject.org/ to learn more.