Quoting Rachel & Chris:" it is like 3/4 water and 1/4 milk"
Do you mean if you put some in a bottle and fridge it till later? Usually the fatty stuff separates from the watery foremilk so it looks as you describe. Maybe google image to find some pics and see if it's like what you're producing? (idk if there will be any, but worth a try)
If he has dirty and wet diapers and is growing then it's probably normal. Some women have a milk imbalance (i did) and it can make you produce a bit more watery milk than hindmilk, but it's ok and still better than formula.
Are you pumping?