Although the U.S. has one of the safest water supplies in the world, there are some cities — like Flint, Michigan, and Jackson, Mississippi — that have routinely had water contamination problems.

Polluted water is unsafe for anyone to drink, but it can be especially harmful for expectant moms and young children — which is why some cities are issuing warnings to moms-to-be and parents of young kids to avoid water from the tap. When in doubt, ask your practitioner for advice. 

Here’s what expecting moms should know about where drinking water comes from, how it’s been treated and if it’s safe to drink.

What does "safe water" mean?

"Safe water" is tap water that won’t harm you if you drink it. Safe water contains low levels of contaminants like microorganisms and organic and inorganic chemicals.[1]

What are some common water contaminants?

In most cities and homes, the water that comes from the tap is both safe and drinkable. But rarely, that crystal clear water pouring from the tap contains contaminants that at high levels may cause problems for young children and pregnant women.

A few of the most common contaminants and why they’re especially problematic during pregnancy include:

Lead

One of the most serious toxic substances, lead can leach into tap water through corroded lead pipes, including those in your home or those that bring water to your neighborhood.

Homes built before 1986 are more likely to have lead pipes or lead soldering between the pipes&nbsp than newer homes, and pipe corrosion is more likely to occur when your water has high acidity or low mineral content. 

Lead exposure during pregnancy and childhood has been associated with various cognitive and attention-related behavioral problems later on.[2]

Microorganisms and bacteria

E. coli, Giardia and noroviruses can potentially infiltrate a city’s water supply or your neighborhood well water through sewage or animal waste contamination.

These can cause gastrointestinal illnesses, which can be more problematic for moms-to-be because their immune systems are suppressed.

Pesticides

The organic chemicals glyphosate or atrazine may get into the water from agricultural pesticides and runoff from crop production. Some evidence suggests drinking atrazine-contaminated water can affect a baby’s growth in utero.[3]

Industrial chemicals

These enter the water supply from factory and manufacturing plant runoff.

Disinfection byproducts

Chloroform is one example of this type of contaminant, which forms when chemical disinfectants react with naturally-occurring organic matter in water. Some small studies have found a link between disinfection byproducts in drinking water and an increased risk of birth defects, but most experts agree the evidence is too limited to be conclusive.

Nitrates and nitrites

These end up in the water supply through fertilizer, livestock manure and human sewage runoff. Some studies have linked high levels of nitrates with thyroid dysfunction in pregnant women, which may lead to complications, but more research is needed. 

Arsenic

This metal contaminant can enter the water supply from natural deposits in the earth or from industrial pollution. Elevated arsenic levels in private wells may come from agricultural pollution. High levels of arsenic during pregnancy have been linked to an increased risk of miscarriage, birth defects and preterm birth.

How to ensure you’re drinking safe water during pregnancy

About 90 percent of the water in the U.S. comes from public water systems, which are regulated and kept safe by the Environmental Protection Agency (EPA). 

The other 10 percent of water in the U.S. comes from private wells. Well water can also be safe, but you’ll have to do some occasional tests on your own to protect your water.[4]

Public water supply

The majority of the water we drink comes from public water systems, which means you don’t have to worry about its safety. Most cities’ water supply is tested frequently and considered safe to drink unless the local government notifies you otherwise. 

In the event of a natural disaster or chemical spill, pay attention to alerts and warnings about disruptions to the water supply, which could affect how safe it is to drink. 

If you haven’t heard any local warnings but want to be extra safe, you can contact your local water supplier, health department or the EPA. The EPA requires all community water systems to prepare an annual report called a Consumer Confidence Report (CCR),[5] so reach out to your water utility company if you’d like to receive a copy.

What should make you suspicious when it comes to your tap water? You may notice that the taste is off, your water smells funny, the color isn’t right or your pipes are deteriorating. 

If there’s a possibility that your water supply is compromised, you can arrange to have it tested. You can get a list of certified testing laboratories from your state or local drinking water authority. Talk to your practitioner if you have questions.

Private well water

If your water comes from a well, it’s a good idea to have it tested once every year or two, just to make sure it doesn’t have high levels of chemicals that could harm you or your developing baby.

Experts recommend testing more often if there are known problems with well water in your area, if there was any flooding or ground disturbance in your area, or if you notice a change in water taste, color or odor. Check in with your doctor to see whether that applies to you.[6]

How to ensure you’re drinking safe water during pregnancy

If testing reveals that your water is polluted, you can make a few changes to ensure the water you’re drinking is safe by following these tips:

Install a filter

Invest in a water filter designed to filter specific water contaminants. For example, if your water supply tests for unsafe levels of lead, buy a filtering system certified to reduce or eliminate lead — then use that filtered water for both drinking and cooking.

Buy bottled

Use bottled water for both cooking and drinking if your city’s water supply or your well water contains contaminants. 

Be aware, however, that not all bottled water is free of impurities. Some bottled water actually comes from the tap, so just check first.

Check the purity of the bottled water you’re purchasing by looking for the NSF certification on its label, which demonstrates that the bottler follows regulatory requirements and industry best practices and complies with the regulatory standard of quality.

Boil water before use

If the contamination in your water is bacterial, boiling water before using can kill microbes — but only if health officials have told the public that such steps are enough for your water. Boiling water isn’t effective, for instance, if your water contains lead, arsenic or nitrates.

Let it stand

If your water smells or tastes like chlorine (which is often used to disinfect water), let it stand uncovered for 24 hours or boil it to allow the chemical to evaporate.

Flush your pipes

If testing reveals that your city’s water supply is lead-free but you have lead pipes in your home, always flush your internal pipes by running the water until it becomes as cold as it will get before using any tap water for drinking or cooking. That’s because the more time water sits in your pipes, the more lead it may contain.

Flushing your pipes could take as little as five to 30 seconds if you’ve been using it recently (as with showering or toilet flushing) or it could take two minutes or longer. 

Remember to use only water from the cold water tap for drinking and cooking, since hot water is likely to contain higher levels of lead.

If your city’s water supply itself is lead-contaminated, flushing your pipes is not enough to make it safe. Only filtered or bottled water is okay for drinking or cooking. 

Even if the only lead is in your home’s pipes, filtered or bottled water is your best bet when you’re expecting — just to be extra sure there’s no chance your baby is exposed.

Some reassuring news about lead-contaminated water: Bathing and showering is normally safe for you and your children, even if the water contains high levels of lead. Just don’t drink it.

Another water hazard: BPA

In recent years there’s been increased awareness about possible health risks linked to bisphenol A (BPA), an industrial chemical used in hard plastics and in the lining of food and beverage containers, since it mimics estrogen.[7]

While the Food and Drug Administration (FDA) has banned BPA in the manufacture of baby bottles, sippy cups and infant formula cans, there is some concern about prenatal exposure.

If you want to avoid BPA during pregnancy, stick to BPA-free water bottles. Avoid those with the numbers 3, 6 or 7 on the bottom or use stainless steel or glass containers.