Buy More Water Filters?

Treehugger has a post on Brita's new ad campaign for water filters. Brita is not so subtle on the amout of oil that you are wasting when you drink bottled (instead of Brita-filtered) water:



Besides the obvious point that tap water uses even fewer resources that filtered water, my comment was this

I stopped using a water filter a couple of years ago (now on tap). One thing that bothered me was tossing all those brita/pur cartridges. Don't they also contribute plastic/waste? Does Brita address that issue?

We need filters made out of recycled diapers or somesuch :)

Does anyone know the "whatever footprint" of Brita or other filters/person/year?