Why is my one year old pooping so watery and yellow? he doesn't seem sick or anything he's been acting like he usually does.

Possible dietary: change. It is not uncommon for BM's to become loose if a toddler is drinking more than 4 oz of juice a dat, eating a lot of fresh fruit, or sometimes from lactose intolerance when switiching from formula to milk. I agree that most viral gastroenteritis is usually associated with vomiting or loss of appetite, but not always. Yellow/ green stools occur from rapid transit time from eating to BM