uhhh... glass is silica. maybe it has some extremely small amount of other stuff, usually some other mineral added for colour, temperance etc. there's nothing for it to biodegrade into. it is natural as it stands. get some sand, melt it down and form it into what you want. like maybe a bottle for water.
plastic needs an oil rig, drilling, oil spills, burning fossil fuels, and if sitting long enough with something liquid in it may leach into what you're consuming. blech...
imho, anyone who pays more for water than they do for gas is retarded (usually as they complain about the price of gas). plain and simple.
water comes out of a tap and is filtered to put in a bottle.
gas has to be prospected, dug, drilled, super-structure erected, hundreds of people employed, brought out of the crust of the earth, transported to a refinery, refined, transported to a convenient location and pumped out of more infrastructure.
bottled water has to be one of the most incredible rip offs pushed on mankind. ever. more so than movie theatre popcorn.
here in canada you pay minimum $1.90/L of water. sometimes up to $3.40/L. gas is just under $1.00/L