Milk supply directly related to fluid intake

My little girl is 2 months old and I’ve noticed my milk supply is directly related to the amount of fluids I drink! I’ve read a lot on low milk supply but I’ve never seen this mentioned so I thought I’d share! When I go to work I pump and some mornings I’ll drink a ton of water and those days I always have to pump exactly 2 hours after my last pump and I’ll be in the verge of being engorged. The days I’m busy and slack I’ll go 4 hours and my breasts will just be starting to get firm. Have I just missed this? Is the common knowledge? Hahah