The main principle is keeping the mixture mildly acidic by using plenty of water. If the drink is too strong, it increases the risk of stomach and esophageal irritation and can stress tooth enamel. High-concentration mixes are not a good idea; a water-heavy dilution is safer. Also, avoid drinking it many times throughout the day, because repeated acid exposure is harder on enamel. If you have reflux, gastritis, or ulcers, be conservative or avoid vinegar water altogether. Safety is about dilution and frequency.