What Is The Best Water To Use When Making Your Baby’s Formula?

A common question I often get from moms is – 

…what is the best water to mix with my baby’s formula? 

…does it even matter?

YES! 

The water you add to your baby’s formula needs to be safe. It needs to be free from bacteria and chemicals. 

So, I’m going over the common types of water moms add to their infant’s formula. Plus, I’ll share which type of water is best for mixing with baby formula. 

Let’s Talk About Distilled Water

What’s distilled water?

Distilled water has all minerals and nutrients removed. 

Some moms may question if this is good for their baby because don’t those minerals and nutrients provide benefits, but your baby’s formula already contains all the nutrients and minerals they need. 

Mixing your baby’s formula with water that has been supplemented with minerals or nutrients can cause your baby to consume excess minerals or nutrients. This can cause issues like an electrolyte imbalance.  

To Note: I wouldn’t recommend using distilled water as regular drinking for older infants (6 months+) because everything has been removed including fluoride. 

Let’s Talk About Bottled Water

Bottle water is a safe option for preparing your baby’s formula. Although it often contains a fluoride supplement which isn’t needed until your baby is 6 months of age. 

For babies less than 6 months of age chose low-fluoride bottled water that states it is: 

• Purified 
• Distilled 
• Deionized
• Demineralized
• Went through reverse osmosis

Bottled water can be a great, safe option to use periodically when on the go. 

What about nursery water or baby water? 

Nursery water is basically just purified bottled water that is marketed specifically for babies. Again this often has a fluoride supplement, which isn’t really needed until your baby is older.

Related: 15 + Baby-Led Weaning Breakfast Ideas & Recipes (By Age)

Let’s Talk About Tap Water

Tap water is the most common type of water that parents use to prepare baby formula. This is likely because it’s the cheapest and easiest. 

A few  important things to note when using tap water supply: 

• Make sure your tap water is coming from a safe source
• Add a home filtration system to your tap water if you don’t have one already
• It is the safest practice to boil your tap water before mixing with your baby’s formula

To Note: Home filtration systems don’t remove the fluoride that is added to your drinking water. See the “what about fluoride?” section below for more information on this! 

Related: 18 First Foods for Your Baby-Led Weaning Beginner

Let’s Talk About Well Water

I wouldn’t recommend using well water unless you absolutely have to. I also recommend you use well water with extreme caution. 

Well water can become easily contaminated by the dirt, plants, water, and fertilizers around it. When fertilizer is used in the soil around your well it causes the well water to be contaminated with nitrates which can be harmful to humans if we drink it. 

If you plan on using well water you need to have it tested for toxins frequently. Toxins that need to be tested for include:

• Nitrates
• Copper
• Mercury
• Bacteria
• Viruses
• Lead
• Aluminum
• Selenium
• Ammonia

You can call your local health department to have your water tested. 

Well water can’t be boiled in order to make it safe if it contains harmful chemicals. Nitrates and iron aren’t removed from the boiling process. 

What Is The Best Water To Use When Making Your Baby’s Formula?

Now that we’ve covered all the water sources that are commonly used, let’s talk about which ones are best!

For babies 0-6 months: I would recommend using distilled water. All harmful chemicals, minerals, and nutrients have been removed from the water. Therefore, you can assure your baby is getting what they need – in a safe amount – from their formula. 

For babies 6-12 months: The best water to use for mixing formula is still distilled water. I believe at this age you can be a bit more open to using bottled water or filtered tap water occasionally for preparing your baby’s formula. 

The American Academy For Pediatrics states the best water to use when preparing your baby’s formula is safe, clean water! They don’t specify what type just that it needs to come from a safe source. 

Related: When Do You Start Feeding Baby Food to Your Baby?

Do I Have To Boil The Water I Mix With My Baby’s Formula?

There are mixed recommendations when it comes to whether or not you need to boil the water you use to make your baby’s formula. 

The safest practice has always been to boil the water. This is to kill any bacteria or microorganisms in the water that may make your baby sick. 

The American Academy of Pediatrics just stresses that you provide safe water for your baby. No need for boiling or sterilization. 

Some tips for boiling water for your infant’s formula: 

• Never let it boil for more than a minute – this can increase the impurities in the water
• Boil water until it reaches 158°F or a rolling boil
• Make sure you allow the water to cool to around room temperature before mixing with the formula 
• Test the temperature of the bottle by splashing it on the inside of your wrist before you feed formula to your baby

Related: How to Start Introducing Solids to Your Baby

Your Baby and Fluoride

What is fluoride?

Fluoride is a naturally occurring mineral found in our drinking water. This mineral strengthens the enamel of our permanent teeth and helps to prevent cavities. 

Too much fluoride on your baby’s developing teeth can cause dental fluorosis. Dental fluorosis causes discoloration on your baby’s teeth. This usually appears as faint white lines or streaks. 

Learn more about fluorosis from the American Dental Association.

How do you avoid excess fluoride exposure to your infant?

• Avoid using fluoridated water for mixing your infant’s formula
• If your tap water is supplemented with fluoride use distilled bottled water a few times a day to decrease daily fluoride exposure
• Check with your water company to obtain the level of fluoride in your water – make sure it’s less than 0.7mg/L
• If you are combination feeding – breast milk and formula – using filtered tap water for a bottle or two a day should be fine 
• Always check with your child’s pediatrician if you are concerned about your child’s fluoride exposure

You can contact your public water system to determine if your water is supplemented with fluoride and the specific fluoride level.

Tips for Properly Preparing Infant Formula

Along with choosing a safe water source to mix with your baby’s formula, there are some other tips you should keep in mind to properly prepare their formula: 

• Add appropriate amount of water BEFORE powder formula – learn why here
• Boil the water before mixing if you need to
• Always make sure to mix formula in clean bottles
• Test the formula temperature on the inside of your wrist before offering it to your baby 
• Discard any used leftover formula within 1 hour of feeding 
• Discard any unused prepared formula within 24 hours 
• Mix the quantity of water and formula as recommended by the manufacturer or your pediatrician 
• Do not add water to ready-to-feed liquid formula
• Check the expiration date on your formula before offering to baby

Related: How Much Should Your Baby Eat? A Baby Feeding Schedule By Age

Note About International Formula: 

If you are purchasing formulas from the UK or other countries outside of the United States please make sure to read the preparation instructions. 

The UK uses a different size scoop therefore the directions to prepare are often different. They aren’t one scoop for every 2 ounces like typical US formulas. 

Key Points

If you’ve made it this far here are the key points to keep in mind: 

• Distilled water is the best kind of water to mix with your baby’s formula 
• Bottle water and filtered tap water are great options to use occasionally after your baby is 6 months of age
• Boiled water is not required by the American Academy of Pediatrics, but the safest practice to follow 
• Avoid exposure to fluoride until your baby is 6 months old
• Water BEFORE powder
• Make sure you prepare your infant’s formula according to the manufactures instructions or your pediatrician

Check out my free guide: Superfoods for Babies + Toddlers to help boost the nutritional value of your baby’s meals once they start solid foods!