In this lesson we learn what the gold standard is to ensure that your water is drinkable no matter where you sourced if from. Should you find yourself in an environment where you can't boil water we also cover the best way to purify water to remove as much bacteria, protozoa and viruses as is possible. Remember that water boils at different temperatures depending on the elevation.

You'll need the following items for the practical:

• An empty plastic bottle - 2L or larger is great.

• A knife.

• Some river water.

• A container that can be placed on the fire.

• Any fire making materials to keep a fire going - you get to cheat here and use some fire starters.

• A filtering cloth like a buff or even a handkerchief.

• Some cooled down charcoal, sand, stones, and foliage from the environment.

• A cup to filter in to.

Don't forget your survival game face!