Do you drink bottled water? If so, take a look at this:
I quit buying bottled water a long time ago. Our local water supply is pretty decent and we have a filter on our refrigerator. I have no idea how much money we have saved but I do know our plastic recycling has dropped tremendously. We also quit buying pop which eliminated more plastic.
We have reusable bottles and I try to remember to take one with me whenever I go anywhere. I especially like the insulated Klean Kanteen because it keeps my water icy cold for hours. Now, that said, I will admit to the occasional purchase of bottled water on trips. Sometimes it's difficult to carry around enough reusable bottles, say, for a day of sightseeing. I do make a point of looking for a recycling bin or if I'm carrying a large enough purse, to take the empty bottles home with me.
As in most things, our goal doesn't have to be perfection. If you're a bottled water addict, start by looking for ways to reduce your consumption (not of water itself, of course!). If you don't like the taste of your tap water perhaps some type of filter would help. If it's more of a convenience thing, or that you like your water cold but no ice, get a couple of reusable bottles and keep them filled in the fridge. Set a goal to reduce the number of bottles you buy each week by a certain number. Oftentimes a gradual approach is more comfortable.
Finally, be sure to recycle any plastic bottles you do end up using. Our individual actions matter.