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Preventing Mold in Hydration Systems

Red Mold growing inside a Platypus hydration bladder

Do you see that red stain on the inside of my platypus hydration bladder  in the picture below? That’s mold, like the stuff that grows on our bathroom shower curtain. I only noticed it on my last backpacking trip, and since getting home I’ve tried a few things to get rid of it.

First, I filled up the bladder with water, added 3 chlorine dioxide tablets  and let the bladder sit overnight. The next morning, the red stain was still there.

Next, I tried filling the bladder with boiling water at the suggestion of Red Yeti, a backpacking blogger buddy of mine. That worked a little better. There’s now about half as much red tide in the bladder than before, but it’s still there.

My wife, who finds this problem somewhat humorous says the mold is probably dead, but that the only way I can get it out of the bladder is by scrubbing the inner surface somehow. Unfortunately, that’s kind of difficult with a 3 L platypus since the opening is so small. So I bought a brand new 3 L replacement platy today.

You can avoid getting mold inside your hydration bladder like this by washing it out and drying it after every backpacking trip. When I get back from a trip, I’m usually pretty good about unpacking, drying or cleaning my gear, all except for my hydration bladders, since I often use them for day hikes during the week. I guess that has to change. From now on, I will to set aside a pair of bladders just for trips that I clean and dry when I get home.

In addition to red mold, you also need to be on the look out for black mold that can clog up your hydration valve if you use it for a long time.The best solution to prevent this is to also run boiling water through your tube and valve after each trip, disassemble them and let them dry out separately.


  1. I put a cap full of bleach and fill the bladder with hot water every once in a while. I generally try letting it sit overnight and then rinse it really well. Camelbak makes a cleaning kit that includes a tiny brush that goes inside their tube to clean out the black gunk the kit also includes one for inside the bladder but I don't know if it would fit inside the platypus.

  2. Thanks Rob. I'll have to look into getting the little brush for cleaning the bite vale.

  3. If you have a big enough freezer (you live in the USA – of course you have a big enough freezer!) you could try placing the platy in there between uses.

    It should, at the very least, mean you can get away with only boiling it every few uses (I'd guess – my small freezer's too full of food!)

  4. Great blog. I always enjoy the posts. For my bladder (the one that goes in the pack…) I use denture cleaning tablets. The cheaper store-brand ones work just as well as the expensive guys, and I even throw a couple in my tiny toolbox when I'm on the trail. I also rinse everything out well and store it in my freezer. This seems to keep them clean and fresh. The tabs work really well on Nalgenes too, since they can get manky in a hurry. For a liter bottle, 2 tabs to about a pint of hot tap water, put the lid on and let it work for an hour or so. Shake it around every so often to make sure the fizzy blue stuff gets everywhere. Then rinse with clear cold water and there you go.

    Hope to see you on the trail!

  5. This denture tablet tip is great. I'll definitely try that. I had another platypus go moldy on me last week and I need to find a way to stay ahead of the red tide this summer.

  6. A little hydrogen peroxide will work a lot faster.

  7. I've never cleaned mine. All I put in them is water and when I get home, I dry them out with an aquarium pump.

  8. I think this is the stuff – we get it on our vinyl shower curtains and in the grout in the damp basement shower sometimes…

  9. This is the solution I use now to prevent this mold and kill it off – efferdent! Works great.

    Haven't tried it on the shower curtain though. :-)

  10. If you still have the bladder.. try putting a few tablespoons of baking soda in there. Add hot water.. shake it to dissolve the baking soda.. let it sit for 24 hours.. then make a white vinegar and water solution (preferably hot water) and let that sit for 24 hours.. it worked wonders on my bladder.. when i used the vinegar solution it bubbled up so i decided to hold it for a minute with the cap off so the carbonation could escape.. afterwards.. i put the cap on.. shook it up.. took the cap off ti get rid of the remaining carbonation.. waited 24 hours.. then rinsed it 3 times with hot water.

  11. How do you get the ends off the hydration tube in order to clean it? I got the mouthpiece off, but the ‘L’ shaped pieces at the end prevent me from using the Platypus cleaning brush to clean the tube. I’m afraid to pull or twist too hard on the tubing!

  12. The clear plastic around the valve on my hydration bladder has a slight red tinge. Is this something I should worry about? There also seems to be a small brown spec in between the clear and gray plastic parts that I can’t reach with a brush. Any suggestions are greatly appreciated.

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