The main goal during diarrhea is replacing fluids and electrolytes. Mineral water can help increase fluid intake in mild cases, but it does not replace a proper oral rehydration solution. Some mineral waters are high in magnesium and may worsen diarrhea. Carbonation can also irritate the gut for some people. If diarrhea is severe, accompanied by fever or blood, or involves high-risk groups (children, older adults), medical evaluation and appropriate rehydration are essential. A safer approach is small sips and choosing options you tolerate well.