This instructable shows you how to clean the mildew, mould and accumulated dirt from the plastic hose on your CamelBak or other hydration bladder with nothing but some paracord (and some optional sterilization tablets).

I discovered this neat trick an hour before setting off on a climbing holiday after finding that my CamelBak hose was disgustingly dirty.

Being loathe to spend £20 for a brush on a wire to clean the hose and without time to get one I looked around for something that could clean the hose.

Paracord was the answer! A loose knot in the end of a length of paracord, dropped through the hydration bladder's hose can be drawn through slowly and bring all the gunk with it.

Here's how I've done it ever since.

Step 1: You Will Need....

A dirty camelbak or other "hydration bladder" hose
Milton tablets or other baby bottle sterilisation tablets. You could also use mild soapy water though not too much or you may leave a bad taste. Definitely don't use bleach.
Paracord. About 10cm longer than the hose

Step 2: Soak

Add two Milton tablets to a clean basin full of water. Completely submerge the dirty hose and work all of the bubbles of air out of it. Soak for half an hour.

This softens up all the dried on gunk growing on the inside of the tube.

Don't pour the water away once the hose is soaked, save it for when you're finished cleaning the hose with the paracord then you can steralise the paracord before drying and storing it.

Step 3: Dry

Don't worry too much about this step. Once it's been soaking for a while, remove the tube from the basin and blow through it to remove most of the water. If it's still really wet inside the paracord won't slip down it so easily.

Step 4: Knot and Drop!

Tie a LOOSE knot in one end of your paracord. This is to stop it falling through the tube until we're ready. I have found a figure eight works well.

Drop the non-knotted end down through the hose until it comes out the other end. Make sure you have a neat end on the paracord or it won't make it all the way down the tube! If it gets stuck try holding the end of the paracord in the tube and pulling the length yet to be inserted. This straightens out the cord and helps it slip down. Sucking on the end also helps draw it through.

Move the knot up to the end of the tube and slowly tighten it until you can just push it inside the tube. It should be as a tight a fit as possible. I can feel the bulge of the knot being pulled through the tube when I run it through.

Step 5: Pull It Through

You're now ready for the cleaning to begin! If you have a longer piece of cord than me you could use a piece twice as long and tie the knot in the middle then pull it back and forth instead of re-threading each time.

Slowly draw the knot through the tube by pulling on the other end of the paracord. When it's almost all the way through hold it over the sink; if you've never done this before you'll likely have a lot of black gunk dropping out on your lap otherwise! Mine's cleaned regularly so I can't show you how gross it can get.

Wash off the knot and repeat until you're happy. If the knot wasn't touching all sides of the tube the first pass through you might be able to see stripes down the inside to show the difference between before and after cleaning.

Once clean, rinse and then it's ready to use.