As for avoiding bags I have two wicker baskets like this https://www.amazon.de/-/en/gp/product/B009BMXLLI/ which means I can avoid shopping bags and they are actually quite convenient for carrying.
Tap water is luckily very drinkable in Germany (rumor has it that Coca-Cola company bottles it and sells it under their 'Bonaqua' brand).
However, there is so much out of our control with plastics that require regulation. Just think of the packaging.