My son has been refusing milk for the past 3 days, he only drank a few ounces each day & prefers plain water. He is only 20 months!

Your baby is now almost 2 years old so it is perfectly normal if he does not want to drink too much milk.As long as he is drinking enough water during the day and eating other kinds of food it is alright. The concern only arises if he loses weight or it affects his health in any other way.