How to Clean Hydro Flask?

hydro flask

Whenever I go out, I always carry a water bottle with me.

Many people are becoming more eco-conscious and carrying them with them. Water is especially essential in the summer.

Recommended water bottle

I use the already famous Hydro Flask 18oz (532ml). It’s small enough that I never run out of water, and it’s not too big to carry around. I lost the one I bought myself when I first came to Hawaii, and my boyfriend gave it to me as a gift! They are sold everywhere in Hawaii and have become such a staple that I think everyone has one. They come in a wide variety of colors, lids, and shapes, and have a stylish image.

I used to use a MIZU bottle that I bought in Canada! I liked it a lot and the brand is also very cool! The vacuum structure of the bottle is great for keeping things cool and warm! I’m thinking of using this brand again when this one is no longer available.

If you don’t care about stylish looks or branding, Zojirushi is the best brand for cold and warm storage in my opinion. It keeps ice cold and does not melt at all. You can even bring boiling water to a snowy mountain and eat a cup of ramen. I have yet to find a product from overseas that has that level of cold and heat retention.

But then again, I often lose them when I misplace them.

How to remove dirt from the bottom of a water bottle

I’ve been using the Hydro Flask for over a year now, and it hasn’t gotten that dirty because I’ve been rinsing it out frequently, and I think it’s partly because the Hydro Flask has a large mouth and is flat inside, so it’s easy to wash.

However, my boyfriend’s bottle is under his control, and he says that he only fills it with water, and he doesn’t add water or rinse it properly, so one day I looked at it and saw red rust or black rust on the bottom where the sponge can’t reach. Black rust? Once I saw it, I didn’t want her to use it like that!

I put some detergent in it, shook it, and left it for a while, but I couldn’t get rid of this stubborn stain. But with the following method, as you can see in this picture, I was able to clean it off easily.

dirt from the bottom of a water bottle

Here is the method I tried

Add 1 tablespoon of baking soda and 100 ml of warm water, cover with a lid, shake lightly, and leave it on for 1 hour.

2. Roll up a piece of saran wrap, fill it with water, cover it, shake it lightly, and leave it for one hour.

3. Crush the rinsed eggshells into small pieces, add enough water to cover the eggshells by about 1 cm, cover with a lid, shake gently, and let sit for 1 hour. I wrapped the eggshells in plastic wrap and crushed them, and put only the eggshells in the bottle.

crush the rinsed eggshells


I couldn’t get the stains out with 1 and 2. The saran wrap cleaned the parts that touched it, but not the edges or the small parts.

With the 3 eggs, the whole thing came out amazingly clean and shiny. It doesn’t take much effort and I recommend it.

How to use baking soda and citric acid

The first one, baking soda, didn’t work very well.

If you want to use the baking soda and citric acid method, add 1 tablespoon of baking soda to 100ml of warm water, plus 1 tablespoon of citric acid, cover the water bottle, and shake gently.

Note: Baking soda is abrasive and will damage stainless steel. Avoid using it directly without dissolving it in hot water.

The rough, whitish stains are caused by calcium and other substances. Citric acid is said to work well for this stain.

Methods that work for red rust

Red rust is a stain caused by iron and other substances. Add about 1/10 of vinegar to hot water, cover the water bottle, and shake it gently.

A sponge that can wash the bottom of a water bottle

I happened to find a sponge that can wash the bottom of a water bottle so I bought one. You can also replace the sponge that holds it in place. I thought it would be a good idea to properly wash every corner with it daily and shine it up with an egg once in a while!


This can be used to wash every corner, and since it’s the well-known Gekiochi-Kun, it should clean up in one shot!

So, in summer, let’s drink more water, be careful of heatstroke, and drink clean water!