Can You Put Bleach in a Hydro Flask?

There are many different ways to clean your Hydro Flask bottle when it gets dirty but can you put bleach in a Hydro Flask?

Does bleach clean a Hydro Flask like it does other surfaces or does it actually ruin and damage your Hydro Flask?

You should NOT put chlorine bases bleach in a Hydro Flask because it will cause your Hydro Flask to rust or cause other stains. It damages the protective layer of the stainless steel causing it to corrode. Hydrogen peroxide is safe to use a Hydro Flask though

While you might think it's a good idea to use bleach to get stains out of stainless steel bottles like Hydro Flasks DON'T DO IT as it will actually make even worse stains than the ones your are trying to get rid of.

It's better to wash your Hydro Flask in warm soapy water and to give it a good scrub with a bottle brush.

For a deeper clean use vinegar and a baking soda paste. Click here to learn how to clean a Hydro Flask properly.

Why Can't You Put Bleach In a Hydro Flask? Why Does Bleach Damage Stainless Steel?

If bleach is so good at cleaning things then why is it that bleach damages your Hydro Flask rather than cleans it? The answer comes down to chemisty.

Bleach damages Hydro Flasks because it creates chlorine. Chlorine attacks and destroys the protective chromium oxide layer and then goes over to attack, stain and rust the stainless steel metal underneath. This causes visual stains or even rust to show.

Bleach contains sodium hypochlorite. When poured into your Hydro Flask this reacts with the carbon dioxide that is naturally in the air and produces a chlorine gas.

Chlorine is a powerful oxidizer that will attack most metals. Hydro Flasks are made from stainless steel and chlorine can corrode this.

See, stainless steel is able to prevent rust and prevent itself getting marks because it has chromium in it. This chromium reacts with the oxygen in the air forming chromium oxide. This forms a protective layer over the steel so now more oxygen can get in and cause rust or damage to the steel.

The chlorine gas from bleach will attack the chromium oxide layer on the inside of your Hydro Flask. Once this protective layer has been compromised the chlorine then goes on to attack the metal itself and this causes damage and rust.

Below you can see an image from my article on if Hydro Flasks rust and how to clean them where someone's mum decided to soak bleach in their Hydro Flask for 2 days, causing rust to form.

Hydrogen Peroxide Is Safe To Use With Stainless Steel

Hydrogen peroxide is an oxygen based bleach (not a chlorine based bleach) and is safe to use with stainless steel.

It won't react with the protective chromium oxide layer of the stainless steel in the same way chlorine does.

Many beer manufacturers use hydrogen peroxide in their stainless steel equipment in order to clean it effectively.

It seems you can soak hydrogen peroxide in stainless steel for days without worrying about corrosion, rust or pits.

How To Get Bleach Stains Out Of Hydro Flasks

If you've accidentally put bleach in your Hydro Flask or tried to use bleach to clean it only to find out that it actually caused more harm than good then it can be possible to clean bleach stains out of a Hydro Flask if the stains aren't too bad.

To clean bleach stains from a Hydro Flask you need to scrub away the corrosion exposing fresh undamaged stainless steel underneath. Coca-cola combined with a magic eraser or abrasive cleaner like steel wool can remove bleach stains from a Hydro Flask.

However, the worse the stains are the more difficult they can be to clean.

The goal here is to scrub, polish or otherwise remove the corrosion from the stainless steel on the inside of your bottle.

Then rinse your bottle and leave to dry, allowing the stainless steel to naturally form the protective chromium oxide layer which will protect it from future damage.

Use Coca-Cola + Abrasive Cleaners To Clean a Hydro Flask

Coca-cola contains phosphoric acid which is good at dissolving rust. It's also acidic and carbonated which also aids in the process.

  • Fill up your Hydro Flask with Coca-cola (or any cola) and let it soak overnight
  • Use a Magic Eraser or fine 0000 steel wool to scrub the rust and polish it away
  • You can also add a baking soda paste to the scrubbing process to help
  • Once complete rinse thoroughly and leave to dry for some time
  • Repeat the process if needed.

The downside of using steel wool is that little bits of steel can break off and get stuck inside your Hydro Flask.

Steel wool is usually a lower grade of steel which is more likely to rust. This can cause issues down the line as these little flakes of steel can rust inside your Hydro Flask.

That's why I recommend magic erasers instead as they are made from a plastic foam, not metal, but are still micro-abrasive and good for removing corrosion from stainless steel. They are also great at polishing other surfaces too.

Get some Magic Erasers for cheap at Amazon

Dry Rice + Water + Shake

If you have a Standard Mouth Hydro Flask and can't fit your hand in there to clean it with a magic eraser or fine steel wool then you can try this method to clean bleach stains from your Hydro Flask.

It probably won't be as effective but it's worth a shot.

To make this process more effective fill your Hydro Flask up with Coca-cola and leave to soak overnight before emptying the coke, quickly rinsing your Hydro Flask and then following this process.

Put a bit of dry rice in your Hydro Flask and a little bit of water. Close the lid of your Hydro Flask and then shake vigorously.

Shake it like there is no tomorrow.

Shake it hard, shake it fast and shake it for at least a couple of minutes.

The impacts from the dry ice will act like a polish and start to scrape away and corrosion or rust on your Hydro Flask.

Once complete rinse out the rice and leave your Hydro Flask to dry.

Can You Use Bleach on a Hydro Flask Lid?

While the stainless steel in Hydro Flasks reacts poorly to bleach the lids of Hydro Flasks are made from plastic and the gaskets are from a type of rubber. So can you use bleach on a Hydro Flask lid?

The answer is yes, you can use bleach on a Hydro Flask lid as the plastic and rubber won't react poorly to the bleach.

Bleach can be an effective way to clean mold from the lid of your Hydro Flask if it hasn't been washed properly and mold has built up.

Just make sure to dilute your bleach with water. 1 tablespoon of bleach for a cup of water should do the trick. Don't use concentrated bleach to clean your Hydro Flask lids.

Alternatively you can use vinegar and baking soda to clean mold from your lids if you want to avoid harsh chemicals like bleach. Learn how to remove mold and bad smells from your Hydro Flask.