This sounds like a science class, but stick with me. Tap water can be treated with chlorine or have a high mineral content. Bottled water can be acidic. If your water is too alkaline or too acidic, it can upset your stomach’s delicate balance.
Why Do You Feel Nauseous After Drinking Water? Causes & Fixes – Frizzlife
Think of it like a ricky beverage without the flavor. No sugar to mask the funky chemistry. Try a different brand or a filter. You might be reacting to the water’s personality, not the water itself.