How Often Should You Wash Your Hydro Flask?

Hydro Flasks are great to keep your water cold all day long or to keep your coffee, tea or other drink hot for hours. How often should you wash your Hydro Flask and do you really need to wash it if it's only had water in it?

I own multiple Hydro Flasks. Some I use myself at walk or when going on a hike or to the beach, others my kids like to take to school as their water bottle for the day.

I've done a full write up on exactly how to clean a Hydro Flask properly which you can check out for tips but I wanted to talk about how often you should clean it.

Here are my guidelines for how often you should wash your Hydro Flask.

If used just for water you should rinse your Hydro Flask daily and give it a good wash about once per week or if it starts to smell. If you're using it for anything other than water wash daily to avoid stains or water wash immediately after use.

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Wash It Once Per Week If Used For Water

Most people use their Hydro Flasks for water only. If you're only using your Hydro Flask for water it doesn't need to be cleaned as often.

A daily rinse with hot water is usually enough to ensure you're not drinking water with harmful bacteria in it.

Most people advise washing your Hydro Flask properly in warm soapy water and with a bottle brush about once per week or if it starts to smell funky then that means it's time to give it a good wash.

If you think about it, people regularly use plastic water bottles for days or weeks at a time without washing them and they don't have any issues.

Wash It After Each Use If Used For Anything Other Than Water

If you're using your Hydro Flask to drink anything other than water – tea, coffee, smoothies, soda, lemon water etc – then you should wash your Hydro Flask daily or after each use.

Failure to wash it can lead to mold buildup, can cause stains on the inside of the bottle and can give your bottle a bad smell or even impart bad tastes into your future drinks.

To sooner you wash your Hydro Flask after drinks other than water the better as the longer it is left the more mold and harmful bacteria will build up.

We've all had the experience of leaving something in a bottle or container too long only to have disgusting mold grow in it and it let of a foul stench.

Semi-Regularly Wash The Rubber Gasket

A lot of people don't realise this but the rubber gasket on the lid of your Hydro Flask can build up a fair amount of mold under it if it's not removed and cleaned on a regular basis.

Hydro Flask don't really give instructions or guidelines of how often you need to wash it or how quickly mold builds up. I guess the answer is “it depends”.

If you're using your Hydro Flask for things like smoothies, soda or coffee I would imagine mold would build up much faster than if you're just drinking water from your Hydro Flask.

But even if you're only using cold water in your Hydro Flask mold still will build up in this area over time and you need to remove the rubber gasket and clean it.

Some people may want to do this weekly. I personally only use my Hydro Flasks for water and I try to do this once a month at least but a times it's been a few months between rubber gasket cleans. Click here for instructions on how to clean the rubber gasket.

What Happens If You Don't Wash Your Hydro Flask?

If you don't wash out your Hydro Flask then over time dangerous mold and bacteria will build up. This will lead to a bad odor that may stay in your Hydro Flask even after cleaning.

It can also lead to increased corrosion of the stainless steel as well as a bad taste hanging around in your Hydro Flask even after cleaning.

No one wants to be tasting their week old smoothie mold flavors when they are trying to have a refreshing drink of cold water. There are ways to remove bad smells and odors from your Hydro Flask that can help if you've left your bottle too long between cleans.

Also there is the potential for the lid to get stuck if you leave drinks in your Hydro Flask for too long. As the drink spoils gases are released, this builds up pressure in your Hydro Flask bottle and places an upward pressure on the lid. This can cause the lid to become stuck and hard to get off. Here's how to get off a stuck Hydro Flask lid.

Not washing your Hydro Flask can also potentially lead to the inside of your Hydro Flask starting to rust. Yes Hydro Flasks can rust.

How Often Do Other People Clean Their Hydro Flasks?

Rather than just rely on my own experiences with cleaning I wanted to do some research to find out how often other people are cleaning their Hydro Flasks.

So I searched places like Reddit and found threads of people talking about this exact subject. I've highlight some of their responses below and linked to the threads if you want to read more.

The general consensus seems to be wash your Hydro Flask approximately weekly or 2-3 times a week if only used for water or wash it when it gets smelly.

Below is an image of me washing the stains and dirt off my white Hydro Flask.

Here are some comments from Reddit threads here, here and here

  • “I also only put water in mine and I wash it weekly” – snzzheng
  • “I clean it every Sunday after a week of using it” – Buddymojo123
  • “I try to clean the straw and lid every couple of days. Should clean the compartment itself but I'm not sure how and I have not done that yet.” – Gottagetanediton
  • “Even if you’re only washing it weekly, you should at least be rinsing it out every night. Mine gets 2-3 washes a week if I’m using it all week.” – mhass24
  • “I only clean it once a week but I know people who clean theirs after every use. I only put water in mine though so it’s okay” – km5898
  • “I just rinse mine daily with hot water on the inside and shake it around while closing the lid..add some soap inside if its been a week or two and shake it with the hot water inside for about 10 seconds”

Can You Throw Your Hydro Flask In The Dishwasher?

While it would be great to just throw your Hydro Flasks in the dishwasher when they need a clean unfortunately Hydro Flasks are not dishwasher safe.

Placing your Hydro Flasks in the dishwasher can potentially compromise the vacuum seal ruining the insulation of the bottle. While some people do it without issue it technically voids your lifetime warranty so it's not advised.

Instead you should hand wash your Hydro Flask in warm soapy water and use a hard bottle brush to clean the insides. If you don't have a good bottle brush check out my list of the best Hydro Flask bottle brushes.

The lids however are top rack dishwasher safe so can be placed in the dishwasher. However, the dishwasher will not get out the mold that can accumulate under the rubber gasket. You need to clean this manually by removing the rubber gasket and wiping away the mold. Read more about how to clean mold from a Hydro Flask lid.

See the latest price of Hydro Flask bottles at
(or compare to the price of Hydro Flask bottles at Amazon)