Hydro Flask vs Iron Flask: Which is Best?

Hydro Flask vs Iron Flask: Which is Best?

If you are thinking of a new flask for your outdoor adventures, our Hydro Flask vs Iron Flask comparison is going to help you decide.

For those long days out on mountain trails or camping in the great outdoors, having a high quality flask is important. Not only do they help keep water and other liquids cool on hot days but they also keep hot drinks warm during the cold months of the year.

Aside from retaining the temperature of their content, a good quality flask will last you a long time too. Even if dropped on rocky terrain or in water, choosing the right flask can mean you can use it for years down the line.

Instead of opting for a flask that isn’t going to get the job done, read through our Hydro Flask vs Iron Flask review. We’ll explore the features of these two great flasks, how they compare to each other, and ultimately which one you should choose.

Main Differences Between Hydro Flask vs Iron Flask

The main differences between the Hydro Flask and Iron Flask are:

  • Hydro Flask can be washed in a dishwasher, whereas Iron Flask should be washed by hand.
  • Hydro Flask only has one lid, whereas Iron Flask comes with three different lids.
  • Hydro Flask has quite a limited capacity range, whereas Iron Flask has more sizes available.
  • Hydro Flask has a leak-proof cap, whereas the Iron Flask does not.

Exploring Hydro Flask and Iron Flask Features

hydroflask vs ironflask

These two flasks have several things in common. Let’s have a look at the features that both Hydro Flasks and Iron Flasks have.

Keeping liquids cold

One of the key functions of a flask is to ensure that water or other drinks are kept cold.

This is vital when outdoors on hot days. No-one wants to be out hiking and have to sip warm water when the sun is beating down.

The Iron Flask can keep cold drinks at a low temperature for up to 24 hours. This is great if you are embarking on a long adventure or even camping overnight. Simply fill it up and go about your outdoor pursuits knowing you’ll have cold water all day long.

The Hydro Flask also keeps water and other liquids cold for a substantial period of time. It allows you to fill it up with cold water in the morning and it should still be cold later that day.

Similar to the Iron Flask, it should last 24 hours at a cool temperature. There have been some reports of inconsistencies with the length of time that the Hydro Flask keeps water and other liquids cold for, just something to be aware of.

Heat retention

Another main feature of both of these flasks is keeping hot liquids warm as they are well insulated.

This is important during the colder months of the year. While you may still need cool water to keep you hydrated, having warm drinks like coffee or tea when out hunting or hiking for example, can make the experience a lot more enjoyable.

The Iron Flask has the capability to keep your hot drinks warm for up to 12 hours. This is a pretty decent period of time. Really you can put some tea or coffee into the flask and it’ll stay warm for half a day.

The Hydro Flask also has the capability to keep liquids warm. According to some reports doesn’t seem to last as long as the Iron Flask although it does state 12 hours. That being said, it will keep liquids hot for a number of hours. Just perhaps not the 12 hours that you get with the Iron Flask. For shorter outdoor excursions it should work absolutely fine.

Stainless steel

hydro flask vs iron flask

Another feature that both of these flasks have is that they are made from stainless steel. This has several benefits.

One is that it adds to the overall durability of these flasks as the stainless steel construction is pretty sturdy. You can drop it and it shouldn’t suffer much impact as long as it isn’t from a particularly high height.

Another benefit so that they are both made with 18/8 pro-grade stainless steel so they ensure a pure taste and they are both easy to clean as well. That being said, the Hydro Flask is dishwasher safe whereas it is recommended that you only clean the Iron Flask by hand in warm, soapy water.

Both of these flasks are BPA free which means they are safer to use and also better for the environment. There has been a big push towards BPA products in recent years so it is nice to see both of these flasks removing this from their design.

Powder Coated

The outside of both the Hydro Flask and the Iron Flask are powder coated.

This means that they are more durable and any drops or impacts will be absorbed fairly well. Another advantage of the powder-coated design that these flasks come with is that they can be gripped easier. This is particularly useful if you are trail running or climbing for example and need to grab a drink quickly.

The powder-coated finish allows these flasks to be designed in a wide variety of colors too. The Iron Flask can be found in 18 different colors ranging from aquamarine to graphite to fire red. The Hydro Flask is also available in many colors (11 in total) which includes sunflower, olive, and watermelon among many others.

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Features unique to Hydro Flask

Hydro Flask

There are some differences between the Hydro Flask and the Iron Flask. One feature which is unique to the Hydro Flask is that it comes with a leak-proof cap.

That isn’t to say that the Iron Flask is going to leak everywhere every time you use it. It is just that the Hydro Flask comes with this unique leak-proof cap feature which will cut down on any potential spills and leakages from the bottle.

Another feature of the Hydro Flask is that it is certified dishwasher safe. So, you can easily clean it by putting it in the dishwasher rather than having to wash this flask by hand. A pretty good feature and one that will appeal to you is washing dishes isn’t your strong point.

Features unique to Iron Flask

Iron Flask

The Iron Flask has several unique features too. One is that you get three lids with the Iron Flask whereas with the Hydro Flask you only get one.

You can buy additional lids for the Hydro Flask but they come with a cost while with the Iron flask these are included with the bottle itself. With the Iron Flask you get a Carabiner Straw Lid which also comes with 2 Straws, Flip Lid, and a Stainless Steel Lid. So, really you have several options there for drinking out of this flask and they come with it as well.

Another feature of the Iron Flask range is that they offer their flasks in more sizes. With an Iron Flask, you have the option of 14oz, 18oz, 22oz, 32oz, 40oz, and 64oz capacity. This offers a more diverse range of sizes so you can choose one which is going to suit your needs and what you can carry when outdoors.

Comparing Hydro Flask and Iron Flask Pricing

One area where these two flasks do diverge quite a bit is with their pricing. The Iron Flask is the more affordable model and it is cheaper overall than the Hydro Flask. Both of these flasks come in different sizes although you’ll find a wider variety with the Iron Flask Range.

The Iron Flask comes in sizes:

  • 14oz
  • 18oz
  • 22oz
  • 32oz
  • 40oz
  • 64oz

The Hydro Flask comes in different sizes too but the capacity range isn’t as big. You’ll find it in:

  • 20oz
  • 32oz
  • 40oz
  • 64oz

If your budget is really tight then the Iron Flask is going to be the more affordable option and you also get a better range of sizes too. There isn’t a massive difference in the cost but it is large enough to be noticeable.

Pros and Cons

Hydro Flask Pros

  • Very durable flask made with stainless steel and a powder coating
  • Can keep water cool for up to 24 hours
  • Can keep liquids warm for 12 hours
  • Has a leak proof cap
  • Can clean in the dishwasher

Hydro Flask Cons

  • Pretty expensive flask and has limited size range
  • Doesn’t offer as much color variety as Iron Flask

Iron Flask Pros

  • Comes with three separate lids as standard
  • Available in wide range of sizes and colors
  • Durable and powder coated design
  • Will keep liquids cool for 24 hours and hot drinks warm for 12 hours
  • Very affordable flask and cheaper than the Hydro Flask

Iron Flask Cons

  • Need to hand wash this flask
  • Doesn’t have specific leak proof cap

Are there any alternatives?

YETI Rambler

YETI Rambler

The first alternative that you can consider to the Hydro Flask and Iron Flask range is the Yeti Rambler.

We have had a look at this water bottle previously. It comes with a range of great features which are designed to keep water and liquids cool and warm drinks hot. This includes a double-wall vacuum seal which keeps the contents insulated.

The 18/8 stainless steel construction makes this a very durable water bottle indeed and it comes with a very good grip as well. You should be able to hold onto this flask securely with just three fingers.

In terms of cost it is closer to the Hydro Flask than the Iron Flask. So, a little bit more expensive than some flasks on the market but it is a very good flask and water bottle that is tailor-made for outdoor adventures.

SENDESTAR Stainless Steel Water Bottle/Flask

SENDESTAR Stainless Steel Water Bottle

Another alternative that you can consider is the SENDESTAR Stainless Steel Water Bottle/Flask. It comes in a variety of sizes including 12oz, 24oz, 40oz, and 64oz.

One thing we do really like with these flasks is their design. They come in a number of lovely colors and they have a minimalist but trendy style to them. Perfect for looking good when in the great outdoors and they can double up nicely as an everyday flask too.

Its durability is assured with its 18/8 stainless steel construction and it keeps liquids cold for up to 24 hours and hot drinks warm for up to 12 hours. Ideal as a flask to use on shorter outdoor pursuits as well as longer camping trips. You get two lids with this flask too – a spout lid and a flat cap – so you are well prepared for both hot and cold drinks.

This is a very affordable flask and water bottle too. Overall, a really well-made flask that is perfect for hot and cold drinks and is set firmly in the affordable category too.


Question: Are Hydro and Iron Flasks BPA free?

Answer: Yes. Both the Hydro and Iron Flask are BPA free which means they are safe and better for the environment too. Both Hydro and Iron Flasks are made from stainless steel.

Question: How long will Hydro and Iron Flasks keep water cool for?

Answer: Both of these flasks advertise as being able to keep water and other liquids cool for up to 24 hours. They both achieve this very well even in hot and humid conditions. You may find slightly different performances when used in hot and cold climates.

Question: Can Hydro Flasks and Iron Flasks keep their contents warm?

Answer: Yes. They are both insulated. This means that not only do they keep liquid cold but they keep contents warm too. They can ensure liquids – like tea and coffee – retain their heat for up to 12 hours.

Question: Do I get a warranty with Hydro Flasks and Iron Flasks?

Answer: Yes. Both of these flasks have a warranty. The Iron Flasks come with a lifetime warranty and the Hydro Flasks also come with a lifetime warranty.

Question: Are Hydro and Iron Flasks available in different colors?

Answer: Yes. Both of these flasks have a wide variety of colors to choose from. The Iron Flask range has a wider variety of colors than the Hydro Flasks.

Question: Are these flasks easy to clean?

Answer: Yes. Their stainless steel construction means cleaning either the Hydro or the Iron Flask is really easy. You should note that the Hydro Flask can be put into the dishwasher whereas the Iron Flask instructions say that it should be washed by hand.

Our Verdict: Hydro Flask v Iron Flask – we recommend you opt for the Iron Flask

So, how do we separate the Hydro Flask range to the Iron Flasks?

Both are very good at what they do. They have many things in common such as keeping your water cold and ensuring your hot drinks stay warm for hours at a time. They also have similar construction with their stainless steel makeup, powder coating, and easy-grip design.

In the end, we have to go with the Iron Flask – but it is really close! There are a few different things that just stand out for us when we compare these two. The first is that the Iron Flask is a bit cheaper.

While we always say you shouldn’t skimp on the price (if you can) if it means paying slightly more for a superior product, but the difference in cost is one big plus point. When you weigh up all the features of the Iron Flask, it makes sense to consider the cost as you get a product of similar quality just for less money.

Another reason we are going with the Iron Flask is that it comes with three lids.

This is a big advantage. The Iron Flask has a Carabiner Straw Lid which also comes with 2 Straws, Flip Lid, and a Stainless Steel Lid. These are things that you can buy for the Hydro Flask however they come with the Iron Flask as standard. No point in paying extra for something you can get with the Iron Flask anyway.

Overall we really like both of these flasks but the Iron Flask edges it. It is cheaper to buy. Is of the same quality and comes with some really good extra’s. Ideal for long or short outdoor pursuits and it looks the part as well.

Further read:

David Borgogni

David is a strong advocate of outdoor-related activities and has many years experience backpacking and hiking around the world, including the Italian and Austrian Alps in Europe as well as central and southern Asia. Locally, he has also led many groups cycling through Vermont, Nova Scotia and Wisconsin. David constantly uses and tests the latest gear for the outdoors, which in turn allows him to help others make more informed buying decisions.