it's not in the water compartment, but it's in the hose. Is there any way to clean it and drink from it safely? I've heard of some baking powder/vinegar solution but I don't know.

Bleach. Leave it soaking inside it overnight.

Are there any precautions to avoid mold?

Let it dry open in between uses. I use Camelbak's hanger and let it dry overnight. Also remove the mouth piece so the water in the line drains. Mold tend to grow worse in the line and it's not easy to clean. Bleach works in those cases. Just make sure you rinse it thoroughly so you don't get a bleach aftertaste.

I agree - bleach is the answer. To prevent it, keep it dry and open while it's stored. And as a precaution, you may want to consider soaking it in a bleach/water solution every month or so. Oh yeah - and water only. Anything with sugar will cause an explosion of wildlife.

I keep mine in the freezer between uses.

You can also use denture tablets. They're basically just bleach tablets that neutralize after ~15 minutes.

Nothing in it but water, keep it clean and aired out or full and cold, clean it with bleach every so often. Just like everyone else, that's what works for me.

+1 - I don't use mine for touring as I prefer bottles, but I do use one for MTBing and storing in the freezer is low maintenance. Trying to properly dry a bladder is a PITA!

I remember reading about this method in a mountain bike magazine several years ago. I gave it a try. It was so hard trying to get rid of the mint flavor in the water after several rinses. It's hard for me to recommend this method. It was just like drinking mint listerine. Personally, I think a little bit of bleach works better.

Camelback has a long wire brush designed to clean this tube. Some bleach , hot water & this brush

I used those tablets, but got unflavoured ones. They work fine. Freezing is simpler so I use that now.

one part bleach, one part water soak for a 2 hours and rinse thoroughly?

Oh goodness... Bleach is really powerful stuff. To remove mold, I personally use a teaspoon of bleach and fill up the rest of the bag with warm water. Let it soak for two hours. Again, rinse thoroughly. I'm glad you asked.

I haven't tried storing in the freezer, but sounds like a great idea if you're riding often. If you're not going to use it for a while, make sure you dry it using the methods described above.

okay, I'll do that tonight and store it in the freezer until I need it.

I got the long brush and the plastic hangers for my bladders. After each use, I remove the mouthpiece, drain as much water from the bladder as I can and hang the bladder using the hanger, letting the tub hang loose. I wash the mouthpiece with dish soap. The hanger prevents the sides of the bladder from sticking to each other and allows plenty of airflow. I keep the dry bladders on the hangers all the time. Once every few weeks I use some chlorine bleach to flush the bladders and the tubes. I never had any mold and the water always tastes fresh. I use about two-three tablespoons of bleach per bladder.

Just don't pour concentrated bleach directly to the bladder/tube, mix it with cold water first. Then pour the water into the bladder, make sure it goes into the tube and let it sit there for some time. 10-15 minutes should be plenty. Rinse it thoroughly with cold water. Warm water might increase the intensity and effectiveness of bleach, but since bleach can damage plastics I avoided doing that. So far, no problems using cold water. Rinse with cold water only though, more effective.

I used it once on a tour and I only flushed it with chlorine once in two weeks.

If you use unfiltered tap water you're more likely to get mold and bacteria so might have to flush it more often.

I'm not sure keeping in it the freezer is good for the plastic. I'd rather keep it dry and clean and flush with bleach periodically. Also, lots of bacteria will survive in the freezer. Bleach is more effective.

Too long. Bleach damages plastics if exposed for too long and there is no need, 10 minutes is enough to kill common bacteria and fungi that cause mold and odor.

good shake down. thanks.

Keeping in the freezer has the added bonus of ice water throughout the ride. I use mine 1-2 a week mountain biking or hiking, always keep in the freezer with some water, and no issues with the plastic in the 2-3 years I have had it.

Push a few dry patches through it with your rifle cleaning rod.

on the topic of taste, years ago I was given a camelback as a present, used it for x-c skiing a while (has its own problems, specifically freezing hose or mouthpiece, kinda a pain in the rear actually, even with homemade foam insulation put on...but I digress)

the main gripe I always had was teh plasticy taste, has that changed nowadays? This was many years ago and it kinda put me off using it. ended up just going back to nalgenes in insulated "tea cossies"

btw, this wasnt from mould or anything, just the seemingly natural rubber taste of the thing (yes I washed it many times well, but not to my taste (sic)

Bleach is bought in a plastic bottle. I do not think the concentrations normally used would be detrimental to the bladder, especially if it is only soaked infrequently. On a long tour, we soaked the bladders only once in four months of touring. Leaving it in the bladder longer than 10-15 minutes will eventually remove the dark mould deposits as well as sterilizing the bladder. I don't think they are removed if you only leave it in a short time. My experience anyway, others may beg to differ (as you do, perhaps you can provide evidence of damage or references to it occurring?).

My partner keeps her bladder in the freezer between uses, I let mine dry only. Both treatments seem to work.