How to clean your hydration bladder before your next hike or workout

Water bladder on your bike, water reservoir
Water bladder on your bike, water reservoir

When it comes to staying hydrated during outdoor activities, hydration reservoirs are a delightfully innovative piece of gear. These durable bags hold ample liquid and fit snugly into a pack so you can sip comfortably through a tube, hands-free. They can be a real game changer whether you’re hiking, biking, skiing or walking the dog.

But Jennifer Krupey, vice president of marketing at reservoir and bottle manufacturing brand HydraPak, knows there’s little worse (when it comes to hydration at least) than sucking water through your reservoir tube for the first time half a mile up a steep climb just to get a mouthful of funky, skunky liquid—that may also contain mold, mildew, bacteria and microorganisms—all thanks to the fact that you haven’t washed it since last season.

It’s understandable. Hydration reservoirs (also known as bladders), though extremely convenient, tend to have a few more parts, pieces, nooks and crannies than conventional water bottles, making them harder to clean. But washing—and drying—should happen at least as often as you clean other hydration gear. Here’s how to do it so water tastes fresh, your reservoir doesn’t get slimy, and you don’t end up drinking harmful bacteria.

How often to clean a hydration reservoir

First things first: if you don’t think your reservoir needs cleaned, you’re probably wrong. It doesn’t take long for reusable vessels to build up more bacteria than you’d find on your computer mouse or kitchen sink. So while ideally you should wash it after each use, Krupey says doing so at least once every six uses or so is acceptable, but only if all you put inside is water. If you’re adding other beverages like juice, electrolyte mixes, or recovery drinks to your bag, you should fully clean it after every use.

That’s because studies show that these ingredients provide a feast for bacteria that multiply more quickly. What’s more, ingredients like sugar don’t easily rinse away. They tend to build up in bite valves, hoses, and nooks and crannies, so simply running them under a faucet won’t do, Krupey explains. The only solution: clean with good ol’ soap and water.

How to wash a reservoir

Before you start cleaning, check the recommendations from the brand that made your bladder. Most publish dedicated step-by-step instructions or guidelines on their website. After all, every reservoir is different and requires different care. HydraPak reservoirs, for example, can be turned inside out for easy washing and drying and are dishwasher safe, but that’s not the case with many bladders.

No matter what type of reservoir you own, though, soap and water is always a good place to start.

1. Open the top and remove the hose from the body of the bladder. Skip this step and liquid could remain stuck in the hose, which could leak back into the bladder later.

2. Use simple dish soap and warm water and wipe down the inside of the bladder with a clean sponge or brush. Make sure you get in all the corners.

3. Rinse well and hang the bladder to dry.

If your reservoir has been sitting in storage for a while, the inside is getting slimy, or it has a weird odor, it may require a deeper clean to help get rid of mildew or off tastes. If that’s the case, wash it thoroughly as described above, then use a special cleaning tablet like those sold by most reservoir manufacturers, which when combined with water are designed to easily clean and sanitize with little effort.

But while you’ll find the recommendation to clean with bleach splattered across the web, Krupey doesn’t recommend doing so, nor does Osprey, another reservoir manufacturer. So skip it.

Another cleaning solution to ignore: freezing your reservoir in lieu of washing it. If your goal is to kill germs, studies show that while freezing can kill and slow the growth rate of some microbes and bacteria, it doesn’t kill everything. And as soon as your bladder thaws, what’s left will start to multiply. So stick with washing for the best clean.

At the very least, even if you don’t have time for a thorough washing, Krupey says, empty the reservoir when you get home and hang it to dry. Moisture breeds bacteria.

Get rid of funky flavors

Where freezing can come in handy is if you’ve washed and sanitized your reservoir and there are still some funky flavors lingering, which Krupey calls “flavor hangovers.” To get rid of them, add the juice of one lemon into a reservoir three-quarters full of water, seal it up, and stick it in the freezer.

Once it freezes, remove it and let it thaw, then drain and dry it. Funky flavors should be neutralized.

Don’t forget the hose

The hose and mouthpiece on your reservoir are trickier to clean, but important, since they’re excellent places for mold and bacteria to hide.

Krupey recommends using a tube brush, which is often part of a cleaning kit offered by most bladder manufacturers. Picture a wire cleaner with bristles on the end like you might use to scrub out the inside of a reusable straw, but much, much longer.

To use it, remove the hose from the bladder, open the bite valve or remove it completely if that’s an option, add a drop or two of soap onto the brush, and slide it through the wet tube several times. Rinse thoroughly and set it aside to dry.

If you don’t have a brush, you can also soak the tube in a bowl with the same tablet cleaner you used for the inside of the reservoir, Krupey advises. Just make sure the valve is open so water can flow through.

If the bite valve comes apart (check with the manufacturer to see if it should—there may be a silicone sheath and possibly a plastic post that plugs into the valve itself), disassemble it and scrub all the bits and pieces with soap and water.

Drying and storing your hydration bladder

Anyone who’s ever used a hydration bladder knows what a pain it can be to get the inside completely dry. But an easy way to promote quick drying is to hang the bladder upside down in a cool, dry place with the cap or hose stuck in the opening to prop it open to promote airflow. You can turn the bag inside out to expedite the process if your bag is designed to do so, but expect it to take a few days for every last drop of water to evaporate depending on the humidity levels where you live.

Another option is to purchase a tool like a BōnDry insert, a strip of material designed to slide into your reservoir and speed evaporation, not just absorption (which is all a paper towel will do), often drying it out in hours instead of days.

As for the hose, Krupey recommends spinning the detached hose around in a circle with the valve open—picture a cowgirl with a lasso—to whip out the moisture inside.

Do it all and you’ll have cleaner tasting water, less slime, and fewer funky smells—not to mention bacteria—lurking in your reservoir. Plus, it’ll last last much longer, Krupey says. And who doesn’t want cleaner water and no need to buy a new reservoir every year?