Also if you want to drink something with a taste, always consider adding tap water to it. Most lemonades mix very well with tap water. Furthermore, not everything you drink requires carbonated water to taste good. Sirups that mix with water in a big ratio like 1 portion of sirup and 10 portions of water are nice too.

Carrying home 10kg of drinks every week seems like such a waste, I never understand people who do that.

Of course if tap water is contaminated because of a flood or some other accident it makes sense not to drink it. That said I think in many places tap water is usually cleaner than bottled water (some more so than others). I understand that I can't generalize, but I think everyone who hasn't should at least read up on the water quality of their region, ideally on official or trustworthy sources.

(edit: Note that I wrote the following paragraph without knowing tap water temperatures. Apparently it only holds true if your cold tap water is below 15°C.)

And since I'm already ranting: You don't need ice in your drinks! It doesn't make the drink tastier or more refreshing. It's just a waste of time and especially energy, and also a contamination risk. You also don't need tap water into the fridge. Just let your cold tap water run for a few second and it'll rinse out the stagnant water that warmed up to room temperature, replacing it with fresher, colder water. I guess in some place this might be more viable than in others. Always depends on the local availability of water and energy.