MakeShift Challenge: Potable Water: “Most Creative” Winning Entry

by William Lidwell
August 08, 2005

The coconut solution is a nice demonstration of lateral thinking. Able to identify and leverage the natural filters surrounding the village, Crossen bypassed the time and complexity of purifying the water and solved the problem straight away. Simple and elegant. Congratulations, Jesse!

A great water purifier would have self-manufacturing, solar-powered nanotechnology and also be cheap. A coconut palm! The trees already use a combination of capillary action and semipermeable membranes to purify the local water, and they even package it in biodegradable bottles. The water inside a healthy young coconut (aged 6 to 9 months) is perfectly sterile and contains a mix of electrolytes and nutrients similar to that of a sports drink. As well as keeping the villagers hydrated, it will keep their muscles working in top form. Coconut water is said to have a mild laxative effect, but I doubt it’s enough to cause real inconvenience. Each coconut contains about 750ml of water, and each villager will require at least 2 liters of water per day, so each villager will need about 2.5 coconuts per day. This means the entire village will need about 75 coconuts per day, which is a good yearly yield for a single coconut palm.

With a small factor of safety for bad coconuts and dead trees, the village will need an orchard of about 400 palms to supply them with drinking water all year. Harvest will require a bamboo ladder, a cutting tool, and a bag or net for carrying. A small group should be able to harvest enough coconuts each morning to supply the village. There are several approaches to delivering the water to the villagers. One is to set up a central processing station to extract the water into barrels for storage and bottles for distribution. However, exposure to air can allow fermentation and contamination of the juice. Another approach would be to pierce the nuts at a central location and then carry them to wherever drinking water is needed. This takes advantage of the coconut’s natural packaging and minimizes opportunities for contaminating the juice between the nut and the drinker.

Young coconuts are normally opened by lopping off their tips with a machete, but a safer and more efficient method might be to use the hand drill to make two holes in the husk and insert a small grass or bamboo straw through one of them. The small holes will minimize spillage in transport, and whittled wooden stoppers can be used to cap a whole batch of nuts for carrying. The labor to harvest the nuts and extract the juice is all relatively easy and safe, and could be accomplished by the village’s children. Assuming it takes a minute to drill a coconut, all the drilling could be done in under 90 minutes a day.

Refinements to the process might include a small pit carved from wood or dug in the ground to hold the coconuts steady for drilling. A bike-powered drill would not provide much extra functionality for the increased complexity. A punch hammered through the husk might be even simpler than the drill, and simpler tools require less maintenance. Overall, this is a basic solution requiring only a few tools and some organization, and is unlikely to break down. If it does, all the components can be repaired or replaced by less efficient methods, e.g., the ladder with climbing or the drill with a machete, until the original tools are fixed.

> More analysis of winning Makeshift entries from Make: 02.