Every once in a while some city water will have a organic contaminate. In Modesto CA in the early 2000s there was a giardia contaminate.
I have heard that all the medications that we use and goes threw us ends up in the tap water, and that is one reason so many people have hormonal issues. I have a little neice that was just born and she has a massive tumor on her brain that has to be opperated on, how the heck can that happen ? Its all a crap shoot I guess.
I am not so sure that city water is safe from minerals, If you have an ary sprinkler head and the water hits your car you will still get hard water stains. Hard water can effect dogs too, can cause kidney or bladder stones in dogs that have a high protien diet. Dogs that seem to be straining when they pee, or pee blood drops need to be checked for stones ( been there ). Apple cider Vinager in the water is one way to flush extra minerals out, and clense the body of contaminates.
So is tap water safe for dogs? I think it is. For puppies? Now, that is where I would err with caution if I did anything at all.
If travelling would you simply drink the unknown quality of the water at your destination or would it be better to purchase the water locally. If the bottled water is found to be contaminated you can sue the butt off the vendor.
The plastic can be recycled, or, as is more common here, just lob it out of the window when you have finished it?