In a fight between our lifeline on the trip, a £250* Katadyn water filter, and a £0.10 concrete slab, the cheaper fellow won.

We spent a long time weighing up the merrits of the filter before we left, but as soon as we got to Sudan, it lept into action. Bottled water was no longer available, taps were an unheard of foreign luxury and the water we could get our hands on, normally from communal 40 litre stoneware jugs on the side of the road in towns, was cloudy and stagnant.
From the moment we had begun using it, bottled water, where it was available, became a more and more expensive luxuary. The filter became a regular fixture in the day. The flexibility it has offered us, especially now that we can bake bread, was invaluable – we could be away from shops for days at a time without worrying about food or water.
Despite only having one month of the trip left, a new core is on its way – the peace of mind the filter has allowed has paid for it many times over.
*bought at cost price by Epic Store.