Seltzer water in moderation is okay for your stomach and may help relieve gas buildup in your stomach.
The Seltzer water can also help relieve an upset stomach such as when you have the stomach flu and don't feel like eating anything.
The seltzer water can help to settle your stomach so that you feel better and it can also help with your digestion.
However if you drink too much seltzer water studies have shown that seltzer water when consumed in excess can leech good calcium from your bones.
That can make your bones brittle and weak so just watch how much seltzer water you drink and you'll be okay.
I would not drink any more than 2 bottles or cans of seltzer water per day and make sure to drink plain water and other healthy drinks.
If you can drink milk you should also because drinking milk helps build strong bones as well.