Water intake during pregnancy is one of those areas where the recommendations are clear, the reasons are well-supported, and yet the question of how much still confuses a lot of expectant mothers. Add in growing concerns about water quality — lead, PFAS, nitrates — and there’s another layer to think about beyond just hitting a daily ounce target.

Here’s a straightforward guide to how many ounces of water to drink while pregnant, why it matters more than you might think, and what the research says about water quality choices during pregnancy.

How Much Water Should You Drink While Pregnant?

The most commonly cited recommendation comes from the American College of Obstetricians and Gynecologists (ACOG): 8–12 cups per day, or 64–96 ounces. The Institute of Medicine sets the target at about 2.3 liters (roughly 80 ounces) from beverages specifically, with additional water coming from food.

The range is intentional. A 120-pound woman doing light activity in a cool climate doesn’t have the same needs as a 180-pound woman working outdoors in July. Physical activity, ambient temperature, body size, and trimester all affect actual requirements. Third trimester typically demands more fluid than first trimester due to increased blood volume and amniotic fluid production.

A practical way to gauge hydration that’s more reliable than counting glasses: check your urine color. Well-hydrated urine is pale straw or light yellow. Dark yellow or amber means you need more water — and that’s a signal worth taking seriously during pregnancy.

Why Hydration Matters More During Pregnancy

Blood volume increases by roughly 50% during pregnancy to support fetal development and placental function. That extra blood requires sustained fluid intake to maintain. Amniotic fluid — which cushions and protects the fetus — is primarily water, replenished continuously by maternal circulation. Dehydration reduces amniotic fluid volume and can restrict fetal movement.

Beyond these direct effects, adequate hydration during pregnancy:

• Supports nutrient transport to the placenta
• Reduces constipation, which affects the majority of pregnant women
• Lowers UTI risk (UTIs are twice as common during pregnancy and carry real complication risks)
• May help reduce Braxton Hicks contraction frequency — dehydration is a known trigger

A 2021 study in the Journal of Nutritional Science found that chronic maternal dehydration negatively impacts birth weight, birth length, and head and chest circumference. The evidence for adequate hydration as a birth outcome factor is compelling.

Signs of Dehydration During Pregnancy

Knowing what to watch for matters, because thirst alone is a lagging indicator — by the time you feel thirsty, mild dehydration has often already set in.

Signs to pay attention to:

• Dark yellow or amber urine
• Noticeably reduced urination frequency
• Dry mouth, chapped lips, or sticky sensation in the mouth
• Headache or lightheadedness when standing up quickly
• Rapid heartbeat or palpitations
• Unusual fatigue unrelated to sleep quality
• Constipation

When to call your provider immediately: Braxton Hicks contractions that increase in frequency, or reduced fetal movement, can both be triggered or worsened by dehydration and warrant a same-day call to your OB or midwife.

Water Quality During Pregnancy: What the Research Says

How much water you drink is important. But what’s in that water is equally important during pregnancy — and this is an area where the science has gotten more urgent in recent years.

PFAS (per- and polyfluoroalkyl substances): A 2023 study published in the Journal of Exposure Science & Environmental Epidemiology found PFAS in 14 of 23 plasma samples from pregnant women — partly attributed to tap water exposure. Pregnant women absorb and retain PFAS at higher rates due to increased daily fluid intake and physiological changes. The EPA finalized the first national PFAS limits in 2024, setting 4 parts per trillion for PFOA and PFOS. Standard carbon pitcher filters remove some long-chain PFAS but fail on short-chain variants. Reverse osmosis removes >90–99% of PFAS compounds.

Lead: ACOG recommends that providers assess lead exposure risk for every pregnant patient — no small recommendation. Lead leaches from older pipes (pre-1986 homes carry the highest risk), and there is no safe blood lead level during pregnancy. RO systems remove >95% of dissolved lead. Simple carbon filters remove essentially none.

Nitrates: This is a newer concern gaining significant attention. A 2025 study analyzing 350,000 Iowa birth records found measurable harm to birth outcomes at just 0.1 mg/L of nitrates — one percent of the EPA’s current “safe” limit of 10 mg/L. Nitrates are linked to preterm birth, low birth weight, and neural tube defects. Risk is highest around week 30. Women in agricultural areas, or on well water, face the highest exposure risk. Reverse osmosis removes 83–92% of nitrates; standard filters remove essentially none.

Filtered vs. Tap Water During Pregnancy

For women on municipal water in a city with modern infrastructure and no known lead pipe issues, filtered tap is a reasonable choice — provided the filter is certified for the contaminants present. NSF/ANSI 53 certification covers lead removal; NSF/ANSI 58 covers RO systems including PFAS removal. Look for these certifications on any filter you buy during pregnancy, not just brand marketing claims.

For women on well water, in older homes (pre-1986), in agricultural regions with nitrate runoff, or in municipalities with known PFAS issues, a reverse osmosis system at the point of drinking water dispensing is the highest-confidence option available. It’s not alarmist to make this choice — it’s precautionary in the same way prenatal vitamins are precautionary.

If you’re not sure what’s in your water, a comprehensive water test is the right first step. Many states offer free or low-cost testing for pregnant women and households with young children, particularly for lead and nitrates.

Tips for Hitting Your Daily Water Goal

Knowing you need 80–96 ounces per day is different from actually drinking it. A few things that help:

• Keep a 32 oz bottle on your desk or counter; drink three of those and you’ve hit the floor of the recommendation
• If plain water tastes off (metallic taste is common in first trimester), adding cucumber, lemon, or mint can make it more appealing — and those additions don’t count against your water intake
• Sparkling water counts — but watch for added sodium in flavored sparkling waters
• Morning sickness makes drinking harder; small frequent sips are easier on a queasy stomach than full glasses
• Set calendar reminders for every 2 hours if you’re the kind of person who gets absorbed in work and forgets to drink

Clean water matters during pregnancy more than at almost any other time. AMPAC USA’s under-sink reverse osmosis systems remove lead, PFAS, nitrates, and hundreds of other contaminants from your tap water — giving you one less thing to worry about.