Why? When I was growing up, bottled water hadn't been invented yet. We all drank city water if we lived in the city and well water if we didn't. We did just fine. My wife grew up on well water and both of us drank it for over twenty years until we retired and moved to a home (and marina) with city water.
I suspect bottle water has been promoted solely for the financial interests of the companies selling it. If you read the labels, much of the bottled water originates from a city water system somewhere. If nothing else, bottled water causes a lot of unnecessary plastic bottles to be produced, used once, and thrown out contributing to pollution and the filling up of landfill space.
First, as to the bottles. Nearly all the plastic bottles from bottled water are recyclable and a huge percentage of them are recycled plastic.
As to the water, when you were young the water quality was much different than today. I've read the water reports of the areas I've lived with the good and the bad. I also know my bottled water originates from city water but is then further treated.
If I only drank occasional water, I'd probably do differently, but water is what we drink almost exclusively. So taste and quality are both very important. We each average about 6 x 16 oz. bottles per day. We drink no tea, coffee, or soft drinks.
I don't know the water in your city, but do in mine and did in my previous home. As to water along the way, I don't know.
But that brings us to one more point. Let's assume the city water is excellent. That says nothing of the miles and miles of decaying pipes running underground to get it from the source to your home. It also doesn't speak to the quality of the pipes from there to your faucets in your home. And it most definitely does not speak to the delivery of the water to the marina locations or of the piping from the road to the marina, to the docks and to your boat. There are a tremendous number of places for the quality and safety to be broken down. The water at your home faucet or reaching your water tank in your boat is far different than the water produced by the city at their plant. It is also less safe, varying by degree in different circumstances. Bottled water doesn't start with safer water, but it does have a safer delivery method in most situations. Now, I'm only referring to bottled city water, not to spring water. Bottled spring water is decidedly less safe than bottled city water.
Most of you drink boiled water (coffee and tea) and factory processed water (soft drinks, beer, juice) for the majority of your water consumption. The average person only drinks a couple of glasses a day of plain water. We each drink 12 a day.
And we have out of curiosity done testing on our own. Part of this grew up out of observation living on the lake where many homes and businesses did not have enough land to have their septic tank and well adequately separated. We've seen some very bad water test results that clearly indicated contamination along the way. This had nothing to do with the quality of the city water.
I would drink water from our watermaker long before I would drink water from a marina. I've had control of it and it's treatment. I don't know anything about the marina water.
I'm not asking anyone to change what they're doing. But we are very comfortable with our choice and will stick with it.
