Maybe I'm missing something, or maybe it is a thing and my area is behind the times but why don't shops have vending machines that dispense water into reusable bottles?
ie. Instead of buying a plastic disposable bottle of Evian/Volvic/Whatever, you pay £X and use your own bottle, or pay £Y and you get a refillable bottle plus the drink?
We have a local vending machine for milk that works like this - why not have one for water?
I'm aware that there are places such as gyms where you can do this from a drinking fountain, but I was thinking more of supermarkets and petrol stations.