Why does my 10-month-old drink so much water?

A 10-month-old drinking lots of water can have several different causes. The most common reason is that transitioning to solid foods — especially salty or dry foods — makes babies thirsty. But sometimes it can signal something else.

Possible causes:

• Diet change: New solid foods (even unsalted homemade meals) increase water needs, especially dry crackers, bread, or high-salt store-bought foods.
• Heat and activity: Increased physical activity from crawling or first steps, plus warm weather, increases fluid loss.
• Dry mouth: A stuffy nose, fever, or mouth-breathing dries the mucous membranes, making your baby want more water.
• Medical conditions (less common): Excessive and uncontrollable water drinking (polydipsia) can sometimes signal diabetes or kidney issues. This is particularly concerning if your baby is also urinating much more frequently than normal, not gaining weight, or seems constantly fussy.

When to call the pediatrician:

• Your baby is drinking more than 500-600 ml (about 2-2.5 cups) per day and it's reducing their breast milk or formula intake.
• Alongside heavy water drinking: very frequent urination, constantly wet diapers, fussiness, weight loss, or poor weight gain.
• Water intake increases noticeably within days with no obvious cause (heat, new food).

General rule: A 10-month-old needs about 200-300 ml of water daily (a cup) with solid foods. More than this can strain the kidneys and reduce breast milk/formula intake, so it's not recommended.

Note: This information is not medical advice; please consult your doctor about medication and dosage.