Why Baby Bottles Leak And How To Fix It! [Dr Browns, Avent, & More!]


If you enjoyed this article, please consider sharing it with others!

Unless you are exclusively breastfeeding, you and your baby are probably going to spend a lot of time with a bottle. The cost of bottles (and nipples, and cleaning brushes, and sterilization systems, and the list goes on) that you need to keep your baby fed can be intimidating, especially when you find out the bottles leak, wasting your precious breastmilk or expensive formula.

While baby bottles can leak because of a product defect or design flaw, it is most often caused by improper use. Proper assembly, feeding position, nipple size and age, and the temperature of the formula or milk should all be considered to fix issues with leaking.

Even “leak proof” bottles can develop leaks if they are old or used improperly. If you have a problem with your baby’s bottle leaking, keep reading for suggestions about what could be causing the bottle to leak, and suggestions for how to fix the leak on your specific bottle type.

Why are my baby bottles leaking?

There are several reasons that your baby bottle might be leaking. While some bottles have very specific designs and special constructions that might cause leakage, it is much more likely that you are putting the bottle together wrong or using it incorrectly.

Don’t worry, you aren’t alone.

New parents have a lot to worry about and when it comes to leaking bottles there are a couple of things that we’ll need to add to the list. Here are the most common reasons that your baby bottle will leak:

  • Nipple age or size
  • The temperature of the milk or formula
  • Proper assemblage
  • Feeding position

Since every bottle design is a little different, we’ll have to approach things a little differently for each one when it comes to assembly of the bottle. In general, however, the other items can be tackled in the same way.

I’ll provide my top choice for a natural and leak-resistant baby bottle, dive into how to stop your bottle from leaking, and then give you a rundown on most of the popular baby bottle brands to help you diagnose your particular issue!

Do all baby bottles leak – what about “zero leak” or “leak proof” baby bottles?

There are a variety of brands on the market that offer “zero leak” or “leak proof” baby bottles, but keep in mind that it is only true under ideal conditions.

There are any number of operator-error mistakes that can be made (especially with the more complex designs) when you are trying to get a bottle ready in the dark at 2 am or even at 10 am with a hungry baby crying at you.

As with any other bottle, it is also important to make sure that all pieces are being replaced as necessary. For instance, most nipples need to be replaced every two to three months, and many manufacturers recommend you replace the bottle itself every six months. In reality, most parents probably think that nipples will last as long as the bottle itself, causing problems in the long run.

The best natural and leak-resistant baby bottle choice

Before I get too deep into the weeds with diagnosing your bottle problems, I do want to give a quick recommendation based on my experience.

In my opinion, the best baby bottles are simple, made from stainless steel, and will last all the way up until it’s time to transition up to sippy cups (or longer!). One product that checks all of these boxes and also is virtually leak-free is the Pura stainless steel baby bottle and you can get a fantastic set that includes everything you need from birth until a year or more. It’s a very reasonable price considering what it comes with and you can check it out right here (along with all of the great reviews from other parents).

Here’s what it comes with:

  • (2) stainless steel bottles
  • (2) medium flow nipples
  • (2) fast flow nipples (with anti-colic tube)
  • (2) XL sippy cup spout nipples
  • (2) silicone travel covers
  • (2) silicone sealing discs
  • (2) removable silicone sleeves for the bottles

These are also all dishwasher-safe, shaped to fit into cup holders, and have a tapered for little hands! You can even pick up a standard water bottle attachment down the road for use once your baby is done with formula or breastmilk.

If you are just trying to find a solution for the bottle you already have, read on! If you are fed up with your current option, then don’t forget to check back here!

How do I stop my bottle from leaking?

No matter what type of bottle you are using, there are several things you can check if you are having leaking issues:

  • Age/condition of nipple – While manufacturers’ recommendations vary, it is a solid practice to replace your bottle nipples every two to three months, or when there is visible wear and tears from little teeth.
  • Size of the nipple – Bottle nipple sizes vary from those permitting only a slow flow of milk or formula to those allowing a fast flow. Typically, the older the child, the faster the flow. If your child is using a nipple size that allows the milk to drip out faster than he can drink it, you are likely to end up with a mess. Tears from little teeth can make this worse. A too-small nipple, meanwhile, will make your baby suck harder, which can lead to a seal breaking or air backing up into a vent and causing a leak in many brands.
  • The temperature of the milk or formula – Liquid that is too warm when the bottle is sealed will increase the air pressure inside the bottle and cause leaks or damage as it tries to find a way to relieve that pressure. A good rule of thumb is to always crack the seal and let out the extra pressure if you have warmed the bottle with the lid already on.
  • The tightness of assembled pieces – This one may seem obvious, but tightening the pieces too much is just as likely to cause a leak as not tightening them enough.
  • Feeding position – Babies feed best when they are sitting up and the bottle is held horizontally or at an angle. When the bottle is held mostly up-and-down, gravity is doing the work that your baby should be doing and the milk or formula drips out on its own. This constant drip can overwhelm your baby and lead to spills or leaks (or even choking, if the flow is too fast). This can also cause issues with gas!

Dr Brown’s bottles are leaking

Dr Brown bottles are some of the most popular baby bottles available because they have a venting system that mimics the flow of feeding directly from the breast and helps reduce burping, gas, spit-up, and colic.

The vacuum created by the vent also helps to preserve the nutrients found in milk and baby formula, allowing your baby to get the most out of each feeding. With the advancement in feeding technology, however, comes an increased complexity in the design of the nipple and more opportunity for something to go wrong, either with the elements of the bottle or in the assembly.

The Dr Brown website provides details directions on how to assemble the bottle properly when it is time to feed your baby:

  • Fill your bottle to the desired amount, being careful not to overfill.
  • Snap the nipple into the nipple collar and place loosely on the bottle.
  • Warm the bottle per warming instructions.
  • Snap the reservoir onto the insert.
  • Remove the nipple and collar and place the reservoir in the bottle.
  • Place the nipple and collar over the vent system and tighten snugly.

As with any bottle, you want to ensure that your baby is comfortable, with his head slightly higher than his chest when feeding. When using a bottle with the Dr Brown vent system, you want to hold the bottle at a 45-degree angle to keep the milk or formula from flooding the vent.

Leaking from the top

There are several reasons that your Dr Brown bottle might be leaking around the collar at the top, most of which are very easy to fix.

  1. Milk or formula was heated with the vent and nipple fully assembled – When the liquid and air in the bottle are heated, they expand and will be pushed out through the vent. Try heating your baby’s bottle before assembling the inner parts. Once the milk or formula is warm, completely assemble the nipple system as directed.
  2. Milk or formula was overheated – If the liquid in the bottle is steaming, it’s possible that the steam is condensing in the vent and leaking out from there. Only heat your baby’s food to body temperature, not hot enough to create steam.
  3. Shaking the powdered formula in the bottle – This will cause some of the formula to get trapped in the vent. Instead of shaking to mix the formula, try stirring it with a long spoon before assembling the system.
  4. The collar is too tight – If the top has been over-tightened, the pressure will build up and relieve itself by leaking. The collar should only be twisted enough to close, resist the urge to try and tighten it to fix a leak.

Leaking when feeding

The vent system in the Dr Brown bottle allows the milk or formula to flow in a way that mimics breastfeeding, but it’s also a more complicated system than the straightforward nipple you see in a standard bottle.

Holding the bottle at the incorrect angle (it should be around 45 degrees) can flood the vent, causing a leak. Another issue could be that the nipple is the wrong size – a hole that is too large can cause your baby to stop the flow out and cause a backup, which would also flood the vent. Alternatively, if the hole is too small, your baby may suck harder in order to get more food and break the seal, creating a leak. 

If you do get milk or formula in the vent, just hold the bottle upright and remove the nipple to release the built-up pressure, then put it back on as normal.

Leaking in diaper bag

If your Dr Brown bottle is leaking into your diaper bag and you have already confirmed that the top is tight, the problem is probably that the bottle is tilting or falling over in the bag and milk or formula is getting into the vent system.

In order to prevent this, insert the traveling disc that came with your bottle under the nipple and take it out when you are ready to feed your baby. You can also buy a travel cap (just make sure you get the right one for your specific bottle type) that goes on in place of the nipple. If you are in a pinch, store your bottle in a pocket in the bag and make sure it stays upright.

Comotomo baby bottles leaking

Comotomo bottles are popular because their shape and silicone construction closely mimics the contour and feel of a breast, and also because their construction is very simple and easy to clean and maintain. If your Comotomo bottle is leaking, it will probably be just as easy to fix.

If the leak is coming from where the top and bottom pieces meet, check the ring and ensure that the nipple has been popped into the ring completely and correctly and the ring has been screwed tightly onto the base. This is a common issue that is easily overlooked!

If the leak is coming from the vents on either side of the nipple, there is probably a little bit of residue clogging the vent. To clean it out, run hot water over the nipple and massage the vents to break up any clogs. After that, place the nipple in boiling water for five minutes; not only will this sterilize the nipple for your baby’s use, it will also help melt any remaining clumps and ensure that the vents are clear.

Philips Avent Natural bottles leaking

Philips Avent Natural bottles are great because the nipple design promotes a natural latch to help avoid nipple confusion, but the bottle system is not overly difficult to assemble or clean even if they may take a little getting used to.

If you check out the base of the nipple, you will see a couple of small notches. When assembling the top, make sure these notches line up with vents to ensure the bottle is functioning properly. The best way to get a good seal when putting the top together is to assemble it immediately after washing when the parts are still wet.

Bottles not venting

If your Philips Avent Natural bottle is leaking because it is not venting properly, it’s likely that the top is not sealed properly.

Obviously, you will have a leaking issue if the top is loose, but tightening it too much will cause the seal to break and leak as well. A good trick for getting it just right is to put the nipple and ring together, then snap the lid onto the top piece before putting it on the base of the bottle. Instead of twisting the ring onto the bottle, twist the cap. Once it starts to spin on its own, the top is correctly tightened.

Air bubbles

You may be concerned when you see bubbles developing in your baby’s milk or formula using the Philips Avent Natural bottle, but they are actually just a product of the design itself. The air you see in the bottle is actually there because the vent is working and the air is in the bottle rather than in your baby’s stomach making him gassy.

Playtex baby bottles leaking

Playtex currently has three different baby bottle designs.

One is a fairly classic bottle design with a simple vented nipple, but the other two are unlike either each other or anything else on the market.

The Playtex Nurser has a disposable drop-in that holds the milk or formula, and the exterior bottle is for the convenience and comfort of holding it while nursing. The biggest issues that you’ll have involve not placing the drop-in bag correctly so that the top can make a good deal.

The VentAire is fairly complicated and has several pieces (so more opportunity for leaks), with both the top and bottom being removable.

Drop-ins leaking

The Playtex Nurser basically contains a drop-in bag for the milk or formula with the traditional bottle exterior being there to make it easier to hold and feed from.

If your Nurser bottle is leaking, check to make sure that there are no kinks or creases in the lip of the drop-in that could be allowing liquid to seep out as your baby feeds.

How to use Playtex VentAire bottles

Playtex VentAire bottles are one of the more complicated bottle systems on the market, but are an excellent choice for your baby when assembled and used correctly. Once the bottle pieces have been washed, sterilized, and dried (that part is important because either slip from the water or expansion from the heat can lead to gaps and leaks), you are ready to assemble the bottle. Since Playtex recommends that the milk or formula be mixed before adding it to the bottle, this is not one you want to prepare in advance.

  1. Place the vent into the base. For most bottle types, this will be the blue piece; for older bottles, it may be clear.
  2. Screw the base onto the bottom of the bottle.
  3. Fill the bottle with prepared milk or formula.
  4. Pop your choice of nipple into the top ring.
  5. Screw onto the bottle.
  6. The angle of the bottle makes it easy to feed your baby sitting up, just ensure that the bottom of the bottle is always held higher than the straight portion while feeding.

Tommee Tippee Closer to Nature bottles leaking

Tommee Tippee Closer to Nature bottles are designed to mimic the feel of and movement of mom’s breast to encourage a natural latch. If your standard Closer to Nature bottle is leaking, check to make sure the nipple is fully snapped into the collar.

Anti-Colic bottle leaking

The Tommee Tippee Anti-Colic bottle has a venting system with a milk heat sensor and a star valve toward the bottom of the bottle. If you have both the Closer to Nature and Anti-Colic bottle types, be sure that you are not interchanging the nipples. The Closer to Nature nipples have a built-in air valve and will leak if used with the anti-colic vent system.

The milk sensor will indicate if the milk is too hot, cool, or just right. While this is great for knowing if the temperature is perfect for feeding your baby, it does double duty as an indicator of whether or not the milk or formula temperature is correct for putting the bottle together. If the liquid is too warm, it will cause steam to condense in the valve and leak out. Dip the sensor about an inch into the liquid for ten seconds to confirm the temperature; once it shows purple, you are ready to put the top on the bottle and feed your baby.

Star valve replacement

When you clean the bottle, make sure to remove the star valve from the venting tube, and do not use the cleaning brush on the valve. If the valve slit has closed up, rinse it in soapy water and pinch it gently between your finger to open it back up. Using the brush on the valve can damage it and cause leaks.

The company does not sell replacement star valves, but you can call customer service and they will send you a replacement.

If you enjoyed this article, please consider sharing it with others!

Josh

I'm the dad in charge of Natural Baby life. With 10 years of parenting experience across three children, I am constantly learning how to raise children more naturally. I'm passionate about doing whatever it takes to raise a happy and healthy baby! Find out more about me here.

Recent Content