Baby Gear Health & Safety

Why Do Dr Brown Bottles Leak? 6 Reasons & Solutions

Thanks to their vented design which is aimed to reduce colic, gas and spit-up, Dr Brown’s bottles are some of the most popular baby accessories out there.

If you are reading this you are probably more than aware of the benefits of these bottles, but there’s also a good chance you are experiencing issues with leakages.

Wasting expensive baby formula and dealing with unnecessary mess can be a big frustration to say the least, so you’re no doubt eager to get to the bottom of things.

There are various reasons as to why Dr Brown bottles leak, ranging from overfilling and incorrect closure, to changes in temperature and even misunderstanding the role of vent system.

Let’s check out in more detail some of the most common reasons why your bottle might be leaking, and more importantly, how to stop Dr Brown bottles leaking in the first place.

6 Reasons Why Dr Brown Bottles Leak (With Solutions)

1. The Collar Is Not On Properly

If you are using a Dr Brown bottle then it’s important to tighten the collar properly to avoid leaking.

Common sense tells us that if the collar isn’t closed tightly enough, then milk will escape and you’ll have a leakage on your hands.

But less intuitive is the fact that leakages may also happen if the collar is closed too tightly as well.

Either way, the vent seal will be broken and ineffective, resulting in the mess you’re currently experiencing.


Close the collar properly, which in practice means tight enough to prevent leaking, but don’t close it too tightly or apply too much pressure when screwing the collar closed.

2. The Vent Is Not Aligned Properly

One of the most common reasons for a leaky bottle is because the vent is not seated properly.

The ventilation system in a Dr Brown bottle consists of two parts that fit perfectly inside each other and then inside the bottle.

To prevent any leaks, it’s vital that parents align the two parts of the vent together, and then once doing so, the round “disc” should sit properly around the collar.


Take extra care when putting the two parts of the vent system together, and then once they are assembled properly without any gaps, ensure the unit sits flush on the neck of the bottle, before screwing the collar on.

3. You’ve Gone Over The Fill Line

One thing you certainly don’t want to do with your bottle is overfill it with breastmilk or formula.

Filling beyond the fill line can cause pressure to build up in the bottle, which in turn results in the vent system not working as intended.


This one’s easy to fix – just make sure you don’t fill up over the max fill line.

If you fill your bottle up to the top and then add in formula you may inadvertently be going over the line, so if you mix powdered formula and water in the bottle, make sure the total amount is still under the recommended maximum fill line.

4. Changes In Temperature

Have you ever experienced a leaking bottle after it’s been stored in a refrigerator or cooler bag?

The reason for this is because temperature changes can cause the liquid in the bottle to expand and contract, which can result in a leak.


Try to avoid any extreme temperatures by leaving a refrigerated bottle out to get to room temperature before feeding your little one.

On the reverse side, don’t let the contents of the bottle get too hot either.

5. The Nipple Flow Level Is Too Slow

According to the manufacturer, another reason why Dr Brown bottles leak can be down to the nipple flow level.

A nipple flow that is too slow will lead your baby to suck harder to get more milk out, which in turn can push air into the event, causing pressure to build up.

As you can imagine, this pressure isn’t a good thing because it can push liquid out of the collar, thereby causing leaking.


If you think the nipple flow is too slow for your child, you should increase the flow level up to the next available level – see age range below:

  • Preemie (0m+ Slowest Flow)
  • Level 1 (0m+ Slow Flow)
  • Level 2 (3m+ Medium Flow)
  • Level 3 (6m+ Medium-Fast Flow)
  • Level 4 (9m+ Fast Flow)
  • Y-Cut (9m+ Fast Flow / Thick Liquid)

Related: Deciding What Baby Gear You Really Need – The Complete Guide

6. Not Using The Travel Disc Or Storage Cap

Did you know that placing the bottle cap over the nipple of your Dr Brown bottle does not prevent liquid from coming out of the nipple when turned over.

That’s because the bottle is classified as an open system, meaning liquid is designed to drip out when the nipple is turned over.

Once you understand this, it’s easy to fix any leaking when you are away from home as follows.


For those times when you’re not out of the house for long – say a walk in the stroller – keep the vent system on, use the travel disc that should have come with your bottle, and ensure the bottle is kept upright.

For longer journeys or when the bottle cannot stay upright for whatever reason – say when flying with your baby – remove the vent, collar and nipple and then screw on a storage travel cap, like the example above.

Nick is a passionate dad who co-founded Rockinbaby to share his parenting journey with other new parents. He has a BSc and MBA, and works as a senior marketing professional. In his spare time Nick loves watching sports, staying fit and traveling. Learn more about Nick here.

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