Should You Be Using Mason Jars as Baby Bottles?

Is that old Mason jar hanging out in your cupboard really safe to pull out and start using as a baby bottle? Probably—but you’ll still want to inspect it carefully. “If it’s clean and been prepared appropriately and washed appropriately, there’s very little in the way of safety risk from reusing glass itself,” says Mark R. Corkins, a pediatric gastroenterologist and professor of pediatrics at the University of Tennessee Health Science Center. According to Corkins, the idea that we have to sterilize everything, including baby bottles, is antiquated. “They thought it all had to be sterile, and we found out it doesn’t have to be,” Corkins says.

CR’s director of food safety research and testing, James E. Rogers, PhD, says that running jars through a dishwasher cycle with hot drying would be good and that, after you begin using them as baby bottles, you should check for residual formula on the bottle. As long as older Mason jars are clean and do not have obvious chips and cracks, Rogers says they should be okay to use. 

Mason jar rings are another story. The metal rings on Mason jars can become notoriously rusty. Jaime Friedman, a pediatrician and director of marketing at Children’s Primary Care Medical Group, says she would not use a ring that is rusty. If your baby has colic or gastrointestinal issues that might benefit from a bottle system like Dr. Brown’s, which comes with bottle accessories designed to decrease burping, spit-up, and gas, Friedman says she wouldn’t recommend trying to make a bottle on your own using a Mason jar and would “stick to the original,” meaning a Dr. Brown’s bottle.

The biggest concern expressed about repurposing Mason jars as baby bottles actually has more to do with the bottle’s design than the safety of its glass. 

As the chair of the committee on nutrition at the American Academy of Pediatrics, Corkins says that a typical baby bottle has markings on the side, whereas some Mason jars may not have these measurement markings. “And basically, you’re supposed to mix so many scoops of powder with so many ounces of water, and the idea is that that makes it the appropriate concentration, you’re not getting too much water and not enough formula, and so you want to mix,” Corkins says. “Not enough formula is not good, and too much is not good because you need so much free water because water’s a nutrient as well. So that is the only concern I would even think about is: If you’re reusing a jar, does it have some sort of volume on the side that you could use?”

One way Corkins says you could get around this is by measuring your formula in a measuring cup and then adding it to the Mason jar bottle. Another option is to invest in new Mason jars designed specifically for baby bottle feeding that you can later repurpose, such as the jars sold by Mason Bottle. “Our branded jars are designed with feeding in mind,” says Kirstyn Velez, Mason Bottle’s director of acquisitions and automation. “The jars have accurate ½-ounce increments.”

Velez says that while any regular-mouth Mason jar accessory would fit to make a bottle, their products are designed specifically for that purpose and with health in mind.

Tony Lee, a spokesperson for Comotomo, says he has heard about parents using Comotomo nipples on Mason jars and how Comotomo replacement nipples perfectly (coincidentally) fit for this purpose, although he can’t comment specifically on the safety of Mason jar bottles.

This mostly positive praise for the ingenuity of repurposing Mason jars as baby bottles doesn’t come without some skepticism. Alan Greene, a pediatrician and founder of DrGreene.com, says that while he really appreciates the idea of reusing high-quality bottles for babies and reducing the amount of waste in landfills, he is unsure if Mason jars are the best option for this. 

“Many parents have no issues finding bottles specifically designed for babies, either as gifts or from friends,” Greene says. “Additionally, some parents may not already have Mason jars in their cupboards, and it can be expensive to purchase the necessary items to convert them for use by their baby.”

The amount of money you’ll save using Mason jars really will depend on whether you already have the appropriate size Mason jars at home—some parents on TikTok use a smaller 4-ounce jelly jar, for example—and how much you’re willing to spend on the accessories you need, including a silicone sleeve to prevent glass from dropping and shattering. 

Let’s say you’re starting from scratch and have to buy everything new:

• $23: a 16-pack of jelly jars from Amazon.
• If you want to buy all accessories from Mason Bottle, a three-pack of rings from Mason Bottle costs around $13.
• $7: a set of four plastic storage rings.
• $4: one plastic cap.
• $17.49: a four-pack of silicone sleeves (this is Mason Bottle’s sale price; the regular price is $36).
• $10: a two-pack of silicone nipples.

Because it’s common for babies ages 2 to 5 months to drink five to six bottles a day, I calculated the cost of buying enough accessories for six Mason jars, minus the silicone sleeves because you can repurpose those easily enough from bottle to bottle. The total price of using Mason jars in this case comes out to $106. Keep in mind that while you may be able to reuse the Mason jar accessories as your child grows, they will outgrow a 4-ounce Mason jar and you’ll have to buy another, larger set of jars at some point.

• $51: six 8-ounce glass Dr. Brown’s bottles, which come with all of the accessories needed to make a bottle but do not include silicone sleeves.
• $16: a three-pack of silicone sleeves designed to fit Dr. Brown’s bottle, bringing your total cost to $67.

Of course, with Dr. Brown’s you aren’t getting the benefit of repurposing the bottles once your baby has grown. 

Mason jar bottles are a clever, eco-friendly idea that allow you to repurpose what you may already have in your pantry, while cutting out waste. Will they save you a ton of money? Probably not. But as long as you’re following safety guidelines for keeping your glass jars clean and shatter-resistant, while also taking care to use clean accessories that are up to this task, you can feel good about jumping on board this trend.