Got some black deposits in the tube of your Camelbak? Dark stuff in the seams? Little black spots? You've got fungus, mold, and bacterial slime inside your hydration pack. Do you really want to drink that stuff? Didn't think so.

First, get the inside of the bladder clean. That's the easy part. You can use a baby-bottle brush. I've found what works best is a long-handled foam paint brush. The point of the foam gets into the seams nicely. Don't use soap, unless you want to taste soap for the next month. Just use plain water for your routine cleanings.

Scrub into the seams, and don't forget to clean inside the port where the hose attaches. (A persistent nasty taste can mean the plastic is degenerating and poisoning you. If an odd taste persists after soaking the bladder overnight in bicarbonate solution -- 1 teaspoon per pint -- buy a replacement.)

If you can't get a brush to a cruddy seam area, squeeze the bladder sideways so the seam touches a flat area. Trap the seam between thumb and finger as shown. Now squish back and forth, working down the seam. Not as good as a brush, but better than nothing.

From time to time, use effervescent denture-cleaning tablets in the hydration-pack bladder. This does a good job of cleaning and removing germ bio-membrane deposits. Put 2 or 3 slow-acting tablets (such as Efferdent) in the hydration pack with cold water. Flip the pack every 5 minutes for 20 minutes. Let some of the fizzy mixture flow down into the tube as you do so. Let the mixture sit in the pack overnight, then rinse it out and let it air dry.

For deeper cleaning of stubborn deposits, use a paste of sodium bicarbonate baking soda (add just enough water to make it squishy) as an abrasive to remove stubborn deposits. The bicarbonate also kills germs and removes unusual tastes such as that "stale plastic" flavor.

After cleaning a slimy "gross-out" hydration pack, sterilize the bladder. This slows down the regrowth of spores and germs. Put about 1/2 cup of water in the bladder and toss it in the microwave. Don't boil the water! Just heat it up, a bit at a time, until the bladder is too hot to touch. Take it out and let it sit flat, so the hot water contacts the entire inside of the bladder. Leave it until the water is cool.

But if you're cheap or only plan to clean the tube on rare occasions, here's a home-made tube cleaner: Get an old derailleur cable. (Clean it first with soap and water if it's greasy!) Slide the derailleur cable through the hose.

Slide the cable, with its paper towel coating, into the tube. (Don't pull on the tube yet.)

Once the knob is inside the tube, squish the tube with your fingers, just in front of the paper towel. Pull on the free end of the derailleur cable. The knob will compact the paper, expanding it so it tightly fills the tube. Now we're ready to clean!

Now put everything back together.