Day One

We're all after water ... Ellen and Ian finding it, me and Mike B purifying it, Jonathan perhaps finding it with a Mars Rover.

Mike B and I decide to separate the tasks - I need to boil the water for at least ten minutes to kill all the bugs, and he will filter it. Of course, I could simply throw it on a fire in a tin but I'd probably lose too much by evaporation, get junk in it from the fire, and I wouldn’t be able to see when it began to boil anyway. The sun's so intense here - I must be able to use its energy to boil water.

Ellen and Jonathan boiled water in Series 2 in Cariacou, so I could just use a parabolic mirror. But they take a lot of time to make and they just focus the light onto one point. I decided to try a funnel-shaped mirror, so that the light is focused all along the length of a whole jar with water in it, so the heating effect is spread out more.

Given we have the tin foil, it's relatively straightforward to focus light. I managed to build a funnel, find some jars with decent seals and spray them black so they'll absorb energy well. I had a go at getting them hot in the sun too. Not quite sure they'll boil water though. Played around with a few different shapes of funnel, too.