Ever seen mold grow? I mean, really grow? It’s disgusting! It smells. It’s nasty to look at. It is bad for your health.
And, yes, mold easily can form in your hydration pack.
In an ideal world, you would drain out, clean, and air dry your bladders every time you put anything in them. However, reality strikes and we end up tossing them in the back seat or trunk instead of cleaning them out properly.
In truth, you do not need to clean it with soap and water every single time you use it, but washing it a few times each year and before you store it away for a while will go a long way to stop mold growth.
The way to keep this from happening is two-fold. The first is cleaning your bladder regularly, but the second, and often overlooked, step is to make sure it dries properly!
How to Clean a Hydration Pack Bladder Properly
There are several ways to clean your bladder, depending on the type of bladder and the amount of work vs money you want to spend.
The first is the good old fashioned scrubbing it out by hand. The second is to use the dishwasher (but this cannot be done on all bladders) The third is to use a bladder cleaning tablet.
Cleaning By Hand
If you cannot turn your bladder inside out (many are not designed to do this) then you will need to make sure you have some brushes that can get inside the bladder (they are not expensive)
If not you will need to use the cleaning tablets we go through later.
- Flush out your hose by holding it above your head and laying the house down and pinch it slightly.
- Add in some warm water and flush it out through your hose.
- Scrub the inside of the bladder as much as you can and then rinse it out thoroughly.
- Use the long piping in your cleaning kit to clean the inside of the tube.
- Half-fill the bladder with warm water and add in a teaspoon of white vinegar and baking soda. If it is really gunky you can also add in a bit of bleach too. Shake the bladder and then let it sit for 20-30 minutes. If you find it does not taste right, repeat this process and add lemon juice to your cleaning solution.
- Remove the mouthpiece and bite valve if your model comes apart. Place them in a bowl of warm soapy water and let them soak for 20-30 minutes too.
- Dump out your bladder and rinse it out well. Flush your hose through with clean water and also rinse the mouthpiece and bite valve.
How to Clean Your Hydration Bladder in a Dishwasher
Some bladders such as the Hydrapack shown here, are reversible and safe to put in the top shelf of your dishwasher. As you can imagine, this makes things much easier!
Literally all you need to do is disassemble your bladder, tube and mouthpiece, turn the bladder inside out and run it through with your dishes.
It does not get easier than this!
How to Clean Your Hydration Bladder With Cleaning Tablets
The easiest option, especially if you are not concerned too much about the mouthpiece and tube, is an effervescent cleaning tablet.
Simply half fill your reservoir with some hot water, add the tablet and let it its fizzing magic do all the work for you.
Depending on the tablet you use, leave it for about 30 minutes (follow the instructions for the tablets you use), then dump the water and flush it through with water and leave it to dry.
These tablets also work for waterbottles, although it seems the height of laziness as water bottles are so much easier to clean (or stick in the dishwasher!)
We really like the detergent-free tablets from Bottle Bright, although you can find ones with a detergent that require less time to clean your pack.
Drying
The steps for drying are the same for all.
- Turn your reservoir inside out (if possible) or hang it upside-down to air dry along with all the other parts. Make sure you put something inside the bladder to make sure the bladder will not stick itself together – I use a paper towel holder!
- You will want to make sure to put your bladder in the freezer when you are not using it to prevent any growth of mildew.
How To Get Rid of Mold in Hydration Packs
If you already have mold, then it is really a case of cleaning everything and making sure there are no nasty bacteria or such-like lurking.
- If you find you already have mold in your bladder, I would advise you to disassemble and scrub it first as directed above.
- Once you have done that, add 2 to 3 tablets of chlorine dioxide, fill the bladder and let it sit overnight.
- Dump the water and then rinse your bladder through with clean water.
- Air dry it as before
- Store it in a freezer to keep it free of mold and kill anything that remains
How To Prevent Mold from Growing in Hydration Bladders
Have 2 different bladders per pack. This may seem like overkill but if you’re able to fill/use/clean/dry one bladder and have another one ready to go then it’s easier to always have a mold-free pack. This is particularly helpful if you’re using a hydration pack daily or smaller hikes.
Wash and dry your bladder after each and every use.
Understanding Different Types of Mold
There are several different types of mold that you will typically see.
- Red Mold is not harmless but it’s not as dangerous as others, like black mold.
- Green Mold could be just about anything unwanted in the fungus department.
- Brown, Olive Green is usually found on plants in the outdoors and can be found on insulation and damp carpets indoors.
- Blue/Green/White is the color of mold that you’ll see on top of perishables that have gone bad in the fridge and bread. This was used to create penicillin years ago.

So, while any mold is bad news mold inside of a hydration pack, it’s not always going to be deadly. However, health risks are present if you don’t take the proper steps in disinfecting and cleaning your hydration bladder after each use.
Pro Tips for Fixing a Leaky Hiking Water Bladder
Unfortunately, if your actual bladder is leaking there is very little that can be done unless you’re super industrious and just don’t want to shell out for another reservoir. However, if you have leaking around connections such as the screw cap for the bladder or where the drinking tube meets the reservoir then try this simple but effective tip:
Use plumbers tape to wrap around the connection and that should help with a watertight seal. This is particularly helpful when temperature changes causes it to expand or contract a bit. (Remember, cold contracts and heat expands.)
Plumbers tape is cheap and easy to use! Boom….you’re welcome!

Matt Green, is an avid hiker and lover of the great outdoors. He is always planning his next big trip or hitting the trails for a solo hike.
He’s traveled extensively to many remote regions and has plenty of experience exploring various terrains, and stories to tell.