How Much Water Should You Drink During Pregnancy?
ACOG advises 8–12 cups (64–96 oz) of water a day in pregnancy. What that looks like in bottle sizes, and why some sources say 3 liters.
Add cucumbers, lemons, limes or a splash of fruit juice to flavor plain water without adding extra calories.
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The short answer: ACOG advises 8–12 cups (64–96 US fluid ounces) of water each day during pregnancy. Drink across the day instead of trying to catch up all at once. This is general guidance; your prenatal care team can help you adapt it to your health and activity.
What does 8–12 cups look like in a bottle?
ACOG uses an 8-fluid-ounce cup, so its range is about 1.9–2.8 liters of drinking water. Your bottle can make the arithmetic easier:
| Bottle or tumbler size | Cups per fill | Fills that equal 8–12 cups |
|---|---|---|
| 16 fl oz | 2 cups | 4–6 fills |
| 32 fl oz | 4 cups | 2–3 fills |
These are volume conversions, not a prescription to finish a certain number of bottles. Check the size marked on your container; a “cup” on a drinking glass may not be 8 fluid ounces. A 500 mL bottle holds a little over 2 US cups.
Why do some sources say 3 liters?
The National Academies' reference for pregnancy is 3.0 liters of total water per day. Total water includes water from plain drinking water, other beverages, and moisture in food. ACOG's 8–12 cups is phrased as water to drink. The two figures count different things, so do not add them together or treat 3 liters as an extra amount to drink on top of ACOG's range. In the National Academies' table for pregnancy, about 0.7 liters of the 3.0-liter total comes from food and about 2.3 liters comes from beverages, which include plain water.
For a simple routine, keep water available with meals and between them. ACOG suggests drinking throughout the day, rather than waiting until you feel thirsty. The U.S. Office of Disease Prevention and Health Promotion recommends plain water in place of sugary drinks. If you also drink coffee or tea, our caffeine guide explains why its amount needs a separate check. If constipation is why you are tracking fluids, our high-fiber foods guide covers the food side.
When should you ask for help?
If nausea or vomiting makes drinking difficult, tell your prenatal care team. The CDC lists being unable to drink for more than 8 hours, or vomiting so that fluids will not stay down, among urgent maternal warning signs. Seek medical care immediately for those symptoms. Ask your clinician how to adjust fluid intake if you have been given a personal fluid limit or have another condition that changes your needs.
Common questions
How much water should a pregnant woman drink a day in ounces or liters?
ACOG's 8–12 cups equals 64–96 US fluid ounces, or about 1.9–2.8 liters of water a day. In 500 mL bottles, that is roughly 4 to 6 bottles.
Does the amount change by trimester or with twins?
ACOG gives one range for pregnancy rather than a separate number for each trimester. If you are carrying twins, have a medical condition, or have been told to limit fluids, ask your prenatal care team for a personal target.
Sources and limits: ACOG's pregnancy nutrition FAQ, the National Academies' water reference, ODPHP's pregnancy nutrition tips, and CDC urgent warning signs. PregNut's food charts do not measure your daily water intake; this guide is educational and does not replace individualized prenatal care.