Short answer: It depends on your local water supply. Most US tap water meets EPA standards, but "meets standards" does not mean "free of concerning contaminants." Babies are more vulnerable than adults to what’s in water — so the answer for your family depends on what’s actually coming out of your tap.
This is the question I get more than any other, and I completely understand the anxiety behind it. You’re mixing formula at 2 a.m. or filling a sippy cup for the first time, and you suddenly wonder: is this water actually safe for my baby?
I’m not going to scare you. The vast majority of municipal tap water in the United States is safe to drink. But "safe" and "optimally safe for a developing infant" are two different standards — and as a parent who has spent hundreds of hours reading water quality reports, I think you deserve the full picture.
Here’s what I’ve learned.
Why Babies Are More Vulnerable Than Adults
Before we talk about specific contaminants, it helps to understand why babies are in a different category than the rest of us when it comes to water safety.
- They drink more water per pound of body weight. A formula-fed newborn consumes roughly 150 mL of water per kilogram of body weight per day. For an adult, that equivalent would be like drinking several gallons daily. Any contaminant in water is proportionally more concentrated for a baby.
- Developing organs are more sensitive. A baby’s brain, kidneys, and immune system are still forming. Contaminants that an adult body can process and flush may interfere with critical developmental windows in an infant.
- Immature immune systems. Babies under 6 months have limited immune function. Their gut barrier is still developing, making them more susceptible to waterborne pathogens and chemical exposures.
- Formula-fed babies get nearly 100% of their water from tap. If you’re breastfeeding, your body does some filtering. If you’re formula feeding, every drop of water your baby drinks comes directly from whatever source you’re using to mix it.
This doesn’t mean tap water is dangerous for babies. It means we should pay closer attention to what’s in it.
The Contaminants That Matter Most for Babies
EPA regulations cover over 90 contaminants. Not all of them are equally relevant for infants. Here are the five I focus on.
1. Lead
The CDC and AAP are clear: there is no safe level of lead for children. Even low levels of lead exposure can cause developmental delays, learning difficulties, and behavioral problems. The EPA’s action level is 15 parts per billion (ppb), but health researchers say there is no threshold below which lead is harmless to a developing brain.
Here’s the important nuance: lead almost never comes from your water source. It comes from your pipes. If your home was built before 1986, you may have lead solder in your plumbing, and older homes may have lead service lines connecting to the water main. The water itself can be perfectly clean at the treatment plant and pick up lead on the way to your faucet.
2. Nitrates
Nitrates are especially dangerous for infants under 6 months. At high levels, nitrates interfere with the blood’s ability to carry oxygen, causing a condition called methemoglobinemia — also known as "blue baby syndrome." This is a medical emergency.
The EPA maximum contaminant level (MCL) for nitrates is 10 mg/L, and municipal water systems are required to stay below that limit. However, if you’re on well water, nobody is testing for you. Nitrate contamination is most common in agricultural areas where fertilizer runoff enters groundwater.
3. PFAS (Forever Chemicals)
PFAS are a group of thousands of synthetic chemicals that don’t break down in the environment or in your body. The EPA finalized its first-ever drinking water standards for PFAS in 2024, setting limits of 4 parts per trillion (ppt) for PFOA and PFOS — two of the most studied PFAS compounds.
Research has linked PFAS exposure to immune system effects in children, including reduced vaccine response. A 2022 National Academies report concluded that PFAS exposure is associated with decreased antibody response, thyroid dysfunction, and increased risk of certain cancers. PFAS have been detected in the water of most Americans, though concentrations vary widely by location.
4. Fluoride
This one is nuanced. Fluoride is intentionally added to about 73% of US public water supplies to prevent tooth decay, and the CDC calls community water fluoridation one of the ten great public health achievements of the 20th century.
However, the CDC also recommends that parents who mix formula with fluoridated water be aware of the risk of dental fluorosis — white spots or streaking on developing teeth. For babies who get nearly all their liquid from formula, the cumulative fluoride exposure can exceed recommended levels. The American Dental Association suggests using low-fluoride water (such as reverse-osmosis filtered water) for formula preparation if fluorosis is a concern.
To be clear: dental fluorosis is a cosmetic issue, not a safety emergency. But it’s worth knowing about, especially if you’re formula feeding exclusively.
5. Disinfection Byproducts
Chlorine keeps our water safe from bacteria — and that’s genuinely important. But when chlorine reacts with natural organic matter in water, it creates byproducts called trihalomethanes (THMs) and haloacetic acids (HAAs). These are regulated by the EPA, but the limits are based on lifetime exposure for adults, not on developing infants.
Some studies have suggested associations between high disinfection byproduct exposure during pregnancy and adverse birth outcomes, though the research is not conclusive. If your water has a strong chlorine smell, that’s not necessarily a safety concern — it just means the disinfection is working — but you may want to filter it for formula use.
Does Your Water Have These Contaminants?
Here’s the thing: whether tap water is safe for your baby depends entirely on what’s in your tap water. And that varies dramatically from one ZIP code to the next.
There are three ways to find out.
1. Use Our Free Water Quality Tool
I built a free water quality checker that pulls EPA data for your ZIP code and tells you what contaminants have been detected in your local water supply. It takes about 30 seconds and will give you a clear picture of what you’re dealing with.
2. Read Your Consumer Confidence Report (CCR)
Every municipal water system is required by the EPA to publish an annual Consumer Confidence Report. This document lists every contaminant that was detected in your water, the levels found, and whether those levels exceed EPA limits. Your water utility should mail this to you or post it on their website. You can also find it through the EPA’s CCR search tool.
3. Test Your Water at Home
Your CCR tells you what’s in the water leaving the treatment plant. It does not tell you what’s in the water at your faucet — and that distinction matters, especially for lead. The only way to know what’s actually in the water your baby is drinking is to test it at the tap.
I recommend Tap Score ($150–$200), which is a certified lab test you can do at home. You collect a sample, mail it in, and get a detailed report with results for lead, nitrates, PFAS, and dozens of other contaminants. It’s especially important if you have older pipes or are on well water.
What Contaminants Does a Standard Brita Handle?
I bring this up because a lot of parents assume their Brita pitcher is solving the problem. Let me be direct about what a standard pitcher filter does and doesn’t handle when it comes to infant-relevant contaminants.
A standard Brita makes your water taste better, but it does not remove the contaminants that matter most for babies. If lead, nitrates, PFAS, or fluoride are in your water, they’re passing right through. Read my full Brita breakdown here.
What to Do If You’re Concerned
If you’ve checked your water and found contaminants above the levels you’re comfortable with — or if you simply want the peace of mind that comes with thorough filtration — here’s what I recommend.
For Formula Preparation
Use filtered water. Specifically, use a filter that is certified to remove the contaminants you’re concerned about. For most parents, that means a filter that handles lead, PFAS, nitrates, and ideally fluoride. Reverse osmosis is the only technology that reliably removes all four.
What NOT to Use
- Standard Brita (white filter) — does not remove lead, PFAS, nitrates, or fluoride
- Unfiltered tap water from homes with pre-1986 plumbing — lead risk
- Untested well water — unknown nitrate and bacterial levels
- Boiled water as a substitute for filtration — boiling concentrates lead, nitrates, and PFAS
When to Use Bottled Water
Bottled water is not my top recommendation for everyday use (it’s expensive, creates plastic waste, and is not always better than filtered tap). But there are situations where it makes sense:
- Emergency situations — natural disasters, water main breaks, infrastructure failures
- Boil advisories — when your water utility says the water is not safe
- Well water that hasn’t been tested — until you get test results back
- Travel — when you don’t know the local water quality
If you do use bottled water for formula, look for purified or distilled water. Spring water is not regulated to the same standard and can contain minerals in variable amounts.
The Bottom Line
Tap water is generally safe for most families in the United States. The EPA regulates public water systems, and the vast majority of municipal water meets federal standards.
But “generally safe” and “optimally safe” are different things when it comes to babies. Your infant drinks more water per pound than you do, has developing organs and an immature immune system, and — if formula-fed — gets virtually all of their water from your tap.
My recommendation is simple: check your water, then decide. Use our free water quality tool to see what’s in your local supply. If anything looks concerning, invest in a filter that actually removes the contaminants that matter. If your water is clean, use it confidently and stop worrying.
Either way, you’ll be making a decision based on data instead of fear. And that’s what thoughtful parenting looks like.