Mam Bottle Leaking: 6 Tips To Quickly Resolve the Problem

It can be extremely discouraging when you prepare your baby’s bottle, only to discover that it is leaking. This can happen even after filling it up and getting ready to use it.

Unlike many bottle styles, Mam baby bottles unscrew at the bottom to make it easier to clean individual parts, but many parents have found milk to leak from the base.

Leaks commonly occur in Mam bottles that are not assembled or used properly. Steps like ensuring the silicone valve is pushed firmly into the base, screwing the base gently onto the bottle, or letting the bottle cool after using boiling sterilizing methods can all help prevent the bottle from leaking.

The extra base part can make Mam bottles a little finicky to use, but once you know how best to assemble and treat these types of baby bottles, you’ll be able to get the most out of them.

Keep reading for our top tips on preventing leaks in Mam bottles plus how to warm and sterilize them.

Tips for Stopping Mam Bottle Leaks

Watching formula and especially newly expressed breast milk go to waste is heartbreaking.

Fortunately, we have some 6 mom tips to ensure your Mam bottles stay airtight during feeds and on the go:

1. Remove the Cap After Shaking the Bottle

After shaking the contents of the bottle, it helps to take the top cap off immediately afterward to release some of the air pressure; otherwise, it may leak out from the base.

2. Push the White Silicone Ring Firmly Into the Base

The white silicone ring/valve needs to be pushed properly into the bottom ring at the base of the bottle.

You can test if it is sealed by pushing around the center ring and raised edge of the valve. If it stays put, you’re good to go!

3. Let the Bottle Cool After Sterilizing in Microwave or Boiling

If sterilizing your bottles using very hot methods (using boiling water or in the microwave), it’s important to allow the bottle to completely cool before assembling the valve and screwing the pieces together.

This is because the resulting heat may have caused the parts to expand slightly, and the silicone valve may not seal in quite as well when hot compared with a neutral room temperature bottle.

4. Try To Use Lukewarm Water for Feeds

The same heat issue applies to the temperature of your feeds.

If you previously used water straight from the kettle to make up your formula, try waiting a little so the water will be hot but not boiling.

This helps limit pressure from the steam building up inside the bottle once you put the cap on.

5. Ensure Nipple Is Attached Properly to Bottle Ring

According to the manufacturer’s instructions, for the nipple to be sealed securely to the bottle, you should hear a “click” sound when the nipple teat has been inserted properly into the bottle screw ring.

6. Screw the Base Onto the Bottle Carefully

It’s possible you’re screwing the base cap onto the bottle too hastily. It needs to be screwed on tightly, but rushing to assemble it may be resulting in leaks.

As per the Mam bottle instructions, the assembled base needs to be screwed on “in a slow steady manner.”

Extra Tip: Also, check the screw threads in the base of the bottle and base cap for any water/residue because unless the screw lines are dry before assembling, it’s likely to leak.

How To Warm Mam Bottles

You can warm mam bottles in hot water by running the open bottle under hot running water (with the cap and nipple teat removed first) or placing the open bottle in a container of heated water for several minutes.

Mam bottles can also be warmed up in the microwave.

To do so, first remove the cap, bottle screw ring, and teat, and place the bottle in the microwave on full power for 20-30 seconds (or slightly longer if warming multiple bottles).

How To Sterilize Mam Bottles

According to Mam Baby product instructions, Mam bottles can be sterilized using one of three methods:

  • Steam sterilizing (using an electric plug-in steam system or in the microwave, according to the manufacturer’s instructions)
  • Sterilizing in boiling water for at least 5 minutes
  • Using a liquid sterilizing solution

Sterilizing using your microwave is a common option, which we’ll discuss below. (Don’t worry if you don’t have a microwave though, as we’ll cover how you can sterilize without one too!)

How To Sterilize Mam Bottles in Microwave

  1. Ensure each of the individual parts is cleaned in warm, soapy water before sterilizing to eliminate any residue (this includes the cap/lid, nipple, bottle body, base, silicone valve, and bottle screw ring/collar).
  2. Rebuild into the four main components, pushing the valve firmly into the base and ensuring that the nipple is pulled through the collar until flush.
  3. Measure out 20 ml of tap water (the lid should have a measure for this), and pour the water into the base.
  4. Stack the bottle components so that the nipple and collar sit in the base inside the body of the bottle with the lid placed on top, but DO NOT screw them together.
  5. Finally, pop the bottle in the microwave on full power for 3 minutes (for 500-1,000 watt models), allowing to cool for at least 10 minutes before use.

How Long To Sterilize Mam Bottles in Microwave

Three minutes should be sufficient for sterilizing your Mam bottle in most standard microwaves.

If yours is a higher-power model (1,500 watts and above), consider reducing the time accordingly by 30 seconds or up to a minute for very high-powered models.

Can You Sterilize More Than 1 Mam Bottle in Microwave?

Absolutely! According to the Mam Baby blog, you can sterilize up to six Mam bottles in the microwave at one time if you wish.

Just be sure to add an additional minute of sterilizing time for each extra bottle.

How Long To Sterilize 4 Mam Bottles in Microwave

It should take 6 minutes to sterilize four Mam bottles in a standard microwave since one bottle sterilizes in 3 minutes, and each additional bottle requires an extra minute.

How To Sterilize Mam Bottles Without Microwave

If you don’t have a microwave, it’s simple to sterilize your Mam bottles using the following methods:


  • Disassemble the bottle components, and place them in a large pot. Cover with water.
  • Bring the pot to a boil, and boil for 5 minutes.
  • Remove the components with clean tongs, and allow to cool.


Simply place each of the disassembled pieces in a plug-in steam system, and follow the instructions for sterilizing, cooling, and drying the components.

Liquid Sterilizing/Bleaching

If you’re unable to boil, steam, or sterilize your baby bottle pieces using a dishwasher, the CDC recommends using bleach.

  • Make up a bleach solution of 2 teaspoons of unscented bleach per gallon of water (16 cups) in a clean wash basin.
  • Submerge all components in the solution, making sure the water touches all parts and that there are no air bubbles in the bottles. Squeeze the solution through the nipple holes to ensure a thorough clean.
  • Leave the components to soak for 2 minutes.
  • Remove with clean hands or tongs, and place immediately onto a clean dish towel or paper towel in a dust/dirt-free area for air-drying.

DO NOT rinse off the components as this can risk the transferral of germs onto the pieces. Any bleach that remains will break down as it dries and will not harm your baby.


Another simple sterilizing hack is to place the bottle components on the top rack of your dishwasher and use the hottest setting.

Just make sure extra small parts can’t fall through the gaps in the rack by using a dishwasher basket!

Related Questions:

Do Mam Nipples Fit Dr. Brown Bottles?

Yes, the Slow Flow Level 1 Mam nipples (designed for newborns and older) are a good fit for the Dr. Brown wide-neck style of bottles.

Some customers have found that Mam nipples are better suited to babies with latching issues as they have a better fit compared with Dr. Brown nipples.

Do Mam Nipples Fit Avent Bottles?

Mam nipples can fit the Avent Classic bottles (made with the bottle adapter rings that screw inside), but Mam nipples may not be compatible with the Avent “Natural” bottles (made with softer, more flexible nipples).

You can refer to this baby bottle and nipple compatibility chart for further guidance.

Closing Thoughts

Leaking Mam bottles can be incredibly frustrating, but if you try the above tips (such as waiting for the bottles to cool before assembling, using lukewarm water for feeds, and screwing the base on steadily), you shouldn’t have problems with your bottles during feeds or while traveling.

To ensure your Mam bottles stay in good shape for longer, be sure to take care when warming or sterilizing them to prevent any cracks, warping, or any other wear and tear that could be quietly contributing to leaks.