Why Does My Hydro Flask Smell Bad? And How to Fix It

Hydro Flasks are extremely popular insulated stainless steel water bottles. They are great for outdoor adventures when you want a hot or cold drink ready to go whenever you need …

Hydro Flasks are extremely popular insulated stainless steel water bottles. They are great for outdoor adventures when you want a hot or cold drink ready to go whenever you need it.

No matter how often you use your Hydro Flask, there will likely come a point where you put it away without cleaning it properly or you simply forget to give it the attention it deserves after some heavy use.

It’s these types of things that can lead to some bad smells inside your Hydro Flask. On top of this (and sometimes worse than this), mold can actually form inside your Hydro Flask.

Mold can lead to some pretty serious health problems if ingested, so if it forms inside your insulated cup, it could quite easily make you sick.

In this article, we look at some reasons why your Hydro Flask might smell bad, including mold growing inside. Once we have established reasons why it might smell, we look at potential ways to fix it and to get your favorite cup back into top condition, ready for your next outdoor adventure.

Can a Hydro Flask Get Moldy?

Can a Hydro Flask Get Moldy?
Hydro Flask or any other type of water bottle can get moldy if not cleaned properly. It is important to regularly clean and dry the bottle to prevent mold growth.

Yes, your Hydro Flask can create conditions that mold likes.

Mold grows best in dark, damp places, so your Hydro Flask bottle makes for an environment where it can certainly thrive. Firstly, your cup will be used to hold drinks. If you are in a bit of a rush or don’t clean it out properly after use, there could still be some moisture left inside. If you add this to the fact that most of us will store our insulated cups in a cupboard or in our kit bags – you then have a dark, damp environment where mold can form.

What Can Happen if You Drink From a Moldy Hydro Flask?

Although most people assume all mold is bad – this isn’t actually true. There are more than 100,000 different types of mold, each one having different properties that can help or potentially harm you.

An example of a beneficial mold is the one used in the discovery of penicillin. This antibiotic has saved millions of lives since its introduction, and it couldn’t have been done without a specific type of mold (Penicillium). Other molds are used in foods such as blue cheese and are known to have some pretty useful health benefits.

However, there are also some very bad molds out there. They can cause vomiting, diarrhea, illness, and, in some cases, death.

Any mold that forms inside your Hydro Flask is highly unlikely to be good for you. While it may not kill you, it probably will make you quite uncomfortable for a day or two if you drink from your moldy Hydro Flask.

There are cases of people being sick for quite a long time that seem to be related to using an improperly cleaned insulated cup. If you use your Hydro Flask regularly, you could be consuming more mold each time you use it, which can continually make you sick.

How to Get Rid of Mold & Smells From Your Hydro Flask

why does my hydro flask smell bad
It is important to clean a hydro flask water bottle to prevent the buildup of bacteria, mold, and other microorganisms. These can cause unpleasant odors, flavors, and even health problems. Regular cleaning also helps to extend the life of the bottle.

Just because your Hydro Flask smells musty, it doesn’t necessarily mean that it is moldy. If you leave coffee in your cup for too long (or any drink with milk in it), it can cause your bottle to smell, and that probably won’t do anything for the flavor of your future drinks.

Whether your Hydro Flask is moldy or just smells bad, both are clear signs that it needs a deep clean.

Wash It Well

Sometimes, giving your Hydro Flask a thorough wash is enough to remove bad smells.

Washing your Hydro Flask bottle can be done by simply filling up a bowl with warm soapy water and, with the help of a bottle brush, giving your Hydro Flask a good clean.

Once you have cleaned your bottle with the bottle brush and water, dry it out and then leave it out to air for a while to make sure it is completely dry before putting it away.

Soak It in Vinegar

If you don’t think warm soapy water will be enough to remove the smell inside your Hydro Flask, then white vinegar might be your best option.

You just need to put a small amount of white vinegar inside your cup, put the lid on it, and then give it a good shake. If you shake vigorously enough, the vinegar will come into contact with all parts of the inside of your cup.

After shaking, leave the vinegar to sit inside your Hydro Flask for up to half an hour. You then just need to thoroughly rinse it out with warm water and allow it to dry completely before putting it away again.

Use Bottle Bright Tablets

Using bottle bright tablets to clean your Hydro Flask is probably the easiest cleaning method.

It’s as simple as putting one of the tablets inside your cup, filling it with water, and then leaving it alone. After the required time has passed, you just empty the water out and let your Hydro Flask dry.

These tablets will cause lots of fizzing and bubbling inside your water bottle, and they do a great job of removing stains as well as getting rid of bad smells. They are made from ingredients such as hydrogen peroxide, baking soda, citric acid, and salt. If you prefer more natural cleaning methods, then bottle bright tablets might not be for you, but if you want a quick and easy way of getting smells out of your Hydro Flask, they could be exactly what you are looking for.

Dry Rice and Detergent/Vinegar

It can be difficult to get every bit of drink residue off the inside surfaces of your hydro flask with just a bottle brush. If you are struggling, put a handful of dry rice in your bottle before adding warm water and detergent or some white vinegar.

You then need to shake your bottle for a few minutes. The dry rice will rub against the inside surfaces and will do a good job of removing any built-up residue. The vinegar or detergent then helps to clean and get rid of the smell.

As always, you just need to give your Hydro Flask a good rinse afterward before letting it completely dry.

Step-By-Step Guide: How to Get Rid of Mold From Hydro Flasks

Hydro Flasks with mold inside will need to be properly cleaned to make sure all organic matter is completely removed before using them to drink from.

Step 1: Rinse Well

Before going any further, you will need to make sure any leftover drink or residue is removed from your Hydro Flask.

Thoroughly rinse it out with water a few times before moving on to the next step.

Step 2: Add a Bit of Vinegar and Shake (Then Leave for 30 Minutes)

Add some white vinegar to your rinsed Hydro Flask, and shake it vigorously for a couple of minutes before leaving it to sit for half an hour.

Step 3: Make a Baking Soda Paste and Use It to Brush Away Mold

Mix some baking soda with water in a bowl to make a paste, and use this, along with a bottle brush, to create a powder coat inside your flask and brush away any mold.

Scrub all inside surfaces of your bottle like this. You will probably get some fizzing when the baking soda interacts with the vinegar, but this is helpful in the cleaning process.

Step 4: Leave to Sit For 15 Minutes

Leave everything as it is to sit for 15 minutes.

Step 5: Rinse With Boiling Water

Rinse your Hydro Flask with hot water. Boiling water can be useful to help with disinfection and cleaning.

Step 6: Scrub Again

With a clean brush, scrub your bottle again to make sure all residue has been removed.

Step 7: Rinse Well

Rinse thoroughly and let your bottle dry.

Hydro Flask Bottle Cleaning FAQs

Can I Clean My Hydro Flask With Steel Wool?

Steel wool can cause scratches to both the interior and exterior of your Hydro Flask, so it is best to avoid using it to clean your bottle.

A bottle brush is likely to be your best option for abrasive power and ease of use.

Can I Put My Hydro Flask in the Dishwasher?

Hydro Flask says that Hydro Flasks should not be put in the dishwasher as it can cause discoloration to the bottle, but, more importantly, it can damage the vacuum insulation the bottle uses to keep your drinks hot or cold.

Some lids are dishwasher safe, but it’s always a good idea to read the care instructions for your specific bottle before deciding on the best cleaning method.

How Can I Prevent Smells and Mold?

Regular cleaning is the best way of preventing smells and mold in your Hydro Flask.

If you want your stainless steel water bottle to stay in top condition, washing your Hydro Flask bottle and your Hydro Flask lid regularly will go a long way in keeping your cup fresh and nice smelling.

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Rob Harvey is an experienced outdoor writer with a passion for using and writing about all the gear that makes camping, hiking and fishing fun. He's been a freelancer writer for more than five years and loves sharing his experiences with readers.
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