PSA please avoid buying bottled water unless you have no other choice.
Depending on where do you live in the world, there's a decent chance bottled water is tap water but approximately 2000 times more expensive.
And even if it's spring water, it's still horribly overpriced and creates unnecessary plastic waste.
Almost certainly, your tap water is more than safe to drink.
If it's too hard or doesn't smell/taste too good (old plumbing…) you can get a water filter.
You can buy a decent water bottle for portability.
But bottled at stores water is a scam.