evidence: Until around 6 months, babies get all the hydration they need from breast milk or infant formula. After 6 months, babies can drink water alongside their regular milk feeds. [...] It is important to wait until a baby is 6 months before introducing water as they need all the nutrients in breast milk and formula. These sources also provide adequate hydration. Providing water before 6 months may mean a baby drinks less breast milk or formula and misses out on important nutrients.