[z2]

>...plastic bottle

I'm even confused by this point--given that some of the water (e.g. San Pellegrino) often comes in glass bottles, can we even assume all bottles measured were plastic? It seems like it should be obvious or else it would be a useless study, but I fail to find a single assertion that all bottled water tested were indeed plastic bottles. That and S. Pellegrino has such a low max count compared with others...

[NegativeLatency]

The bottle may be glass for San Pellegrino, but the cap relies on plastic for a good seal, and you can bet that once the water comes out of the ground it goes through some plastic pipes on its way to the bottle.

[hiccuphippo]

There's probably plastic involved in the process of extracting/bottling the water.

[inimino]

Would you expect glass dust in a water sold in glass?

[dougmwne]

Honestly I would, in microscopic quantities.