As a breastfeeding mum, dd gets milk from my boobs and water from a valveless sippy cup. Milk and solid feeds are very separate for us, so she has water with her 'meals' and breastfeeds inbetween. It seems fine to me that at this young age they still have their milk (formula, cows, EBM, whatever) from a bottle, and water in a cup at mealtimes to wash the solids down!
Ax