Is tap water safe to drink during pregnancy?

What does the evidence say about tap water during pregnancy?

1. NIEHS researchers studying maternal health note that pregnant women may be exposed to harmful chemicals through polluted air and water alongside consumer products and food, placing drinking water among the everyday exposure routes worth understanding rather than a standalone hazard. 1
2. A systematic review of 32 studies covering more than 6 million pregnancies found the overall evidence linking average levels of common drinking-water pollutants to birth defects uncertain, though trihalomethanes and arsenic showed a dose-response pattern at higher exposure levels. 2
3. A Danish nationwide cohort study found preterm birth risk rose alongside nitrate levels in drinking water, including within ranges currently allowed under regulatory limits, with about a 1% increase in preterm birth risk for every 10 mg/L rise in nitrate. 3
4. A survey of women of reproductive age found most had low confidence in practical water-safety steps, such as choosing an appropriate filter or knowing how to reduce lead exposure, pointing to a real knowledge gap rather than evidence that typical tap water needs special handling. 4
5. The same survey found nearly two-thirds of respondents never or rarely ran their tap for a minute or more before drinking or cooking with it, a simple step researchers highlight for flushing out lead that can accumulate in household plumbing overnight. 4

Is tap water safe in each trimester?

• First trimester. Nausea can make plain tap water harder to stomach right when hydration matters most for managing morning sickness. If the taste is the barrier rather than a safety concern, a pitcher filter or refrigerated water often solves it without switching entirely to bottled water.
• Second trimester. This is a reasonable window to actually pull up your water utility's annual quality report or, for a private well, schedule a nitrate and bacteria test, since neither is urgent but both are worth doing before the third trimester gets busier.
• Third trimester. No late-pregnancy restriction applies to water that already meets safety standards. If your home has lead service lines or pipes installed before 1986, running the tap before drinking or cooking stays worth doing right through delivery.