Breastfeeding & Water

Water. What's the deal with milk supply and water consumption? Does a breastfeeding mother have to drink extra fluids to maintain milk supply? Does the amount of water and fluids we drink affect our milk supply at all? Let's find out, you might be surprised!



We've covered the basics for lactation anatomy and physiology (aka the hardware and signals that control milk production) but how is milk made and where does it come from? 

Believe it or not, we make milk from components of our own blood!

In the milk making process, cells in our body extract bits of our blood like proteins, fats, carbohydrates and they go through a synthesis process which takes these bits and pieces of blood and combines them into something new, voila breastmilk (1, 2). Think of this as your body's own culinary process taking ingredients from your blood and creating the perfect meal for your baby, that changes constantly to adapt to whatever your baby's body needs.

Alright, we know we easily geek out about all things milk but you've got to admit, thats pretty awesome. 


Humans lose water throughout the day. We lose water when we pee, when we sweat, when we breathe, and yes, when we make milk (3). Our bodies are pretty good at signaling us to drink fluid when we need it to make up for the water we lose by communicating thirst. What this means is as long as we're drinking (and eating! remember, most foods are composed of some water as well) throughout the day when we are thirsty, we are compensating for water loss.  What this also means is that we generally don't have to force ourselves to drink excess water. Thirst is not always the best indicator however, so it is a good habit to also pay attention to other signs of hydration such as urine output. 


Ready for it? The answer is, no. Contrary to popular belief, there is no evidence to show that drinking more water/fluids affects milk supply (2). While water is essential to our health and helping our bodies function, we do not need to drink more fluid to make milk. Let's repeat that, we do not need to drink more fluid to make milk.

But why not?

When we are breastfeeding, making milk becomes one of the most essential responsibilities of our body. The hormones involved in lactation protect the water we need to make milk and if we drink less water its almost as if our body locks down the remaining water to be used for making milk which is why the rest of the body is affected by dehydration but not our ability to make milk.


If you don't consume enough fluids in a day you may feel some effects of mild dehydration. You may notice you're urine output decreasing (aka peeing less) or notice your urine darker in color, you may feel sluggish, dizzy, nauseous, and have a headache but with mild dehydration you won't see an impact on your milk production (2). 

It is important to make sure you're drinking enough water however, to avoid these unpleasant warning signs of dehydration and to prevent severe dehydration which can be dangerous for your health. Women should stay hydrated and drink to thirst but worrying about how much fluid you're drinking can be taken off your list. A good rule of thumb is drink a minimum of 8 glasses of water/day and drink when thirsty or if you notice signs of dehydration, whether you're breastfeeding or not (2).  This may be plenty of fluid for you or you may find you need to drink more to feel hydrated so adjust as necessary and always follow your body's cues. 

Some mamas, especially in those early weeks, will find they forget to drink water or don't notice their thirst signals (hello, sleep deprivation and competing, sleep, drink!?) and so you may find it helpful to have a designated water bottle or cup to keep track of your water. But remember, drinking water serves a primary purpose to help you and your body run properly and as long as you're not severely dehydrated (e.g. diarrhea, vomiting, fever) it should not impact your milk supply. 


  • Our bodies make milk from components like proteins, lactose, and fats in our BLOOD! 
  • Drinking water helps our bodies function properly and helps us feel good but do not dictate how much milk we make. 
  • Drinking extra water or fluids will not increase our milk supply (you do that by demand and supply!)
  • Aim to drink at least 8 glasses of water/day whether you're breastfeeding or not and following your body's signals! If you notice consistent signs of dehydration such as decreased urine output, headaches, dizziness, fatigue - making sure you're drinking enough water. 


(1) Riordan, J. (2010). The Biological Specificity of Breastmilk In Breastfeeding and Human Lactation (4th ed). Sudbury, MA: Jones & Bartlett Learning

(2) Lauwers, J. & Swisher, A. (2015). Counseling the Nursing Mother: A Lactation Consultants Guide. Burlington, MA: Jones & Bartlett Learning. 

(3) Popkin, B., D'Anci, K., & Rosenberg, I. (2010). Water, hydration, and health. Nutr Rev, 68(8), 439-458.