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 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 playtpus 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.
Popularity: 20% [?]
Related posts:


5 users commented in " Preventing Mold in Hydration Systems "
Follow-up comment rss or Leave a TrackbackI 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.
Thanks Rob. I’ll have to look into getting the little brush for cleaning the bite vale.
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!)
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!
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.
Leave A Reply