Why Is The Price Of A Liter Of Water The Same As For Gas?

I overheard two shoppers (an elderly couple) asking each other this question at the supermarket today. To tell you the truth, I had never really thought about it before. Never even crossed my mind. But it's a very interesting question. Don't you think?
At the writing of this post, I can be anywhere in Montreal and be expected to pay between $1.00 to $1.50 Cdn for a liter of water which is actually more than the current price of under $1.00 for a liter of gas.

Why is bottled water so expensive? ..... some thoughts .....
I would like to hear what you think about this topic.
All comments are welcome.