SlingShot is a compact water purifier designed by the American inventor Dean Kamen, best known for the Segway, and it is also the title of a 2014 documentary by Paul Lazarus about Kamen’s attempt to tackle the world’s shortage of safe drinking water. The machine is a vapor compression distiller: it boils water from heavily polluted sources and condenses the steam into clean water, using less electricity than a microwave oven. It works, but turning a working prototype into something that reaches millions of people has proved far harder than the engineering.
Who Dean Kamen is
Kamen, born in 1951 in Rockville Centre, New York, built his career on medical devices before he became famous for the self-balancing Segway. While still a student he developed one of the first portable drug infusion pumps, the AutoSyringe, which earned him a place in the National Inventors Hall of Fame in 2005. His company DEKA Research and Development has since worked on portable dialysis machines, the stair-climbing iBOT wheelchair and the “Luke” prosthetic arm, approved by the US Food and Drug Administration in 2014.
In 1989 he founded FIRST, a programme that runs robotics competitions for school students and which he has described as the invention he is proudest of. The water purifier grew out of the same habit of mind that runs through his work: find a large human problem and attack it with a single, carefully engineered machine.
How the SlingShot purifier works
Most water filters push water through a membrane or a cartridge that eventually clogs and needs replacing. SlingShot takes a different route. It heats incoming water until it turns to steam, leaving salts, microbes, metals and other contaminants behind, then condenses the steam back into liquid water. Distillation is an old technique; the clever part is efficiency. In a vapor compression distiller the steam is compressed, which raises its temperature, and that heat is passed back to the incoming water. Recycling the energy in this way means the machine needs only a fraction of the power that simple boiling would take.
Wikipedia’s account of the project gives the design goals as about 1,000 litres of clean water a day, enough for the cooking and hygiene needs of around 100 people, while using less than a kilowatt of electricity. Another reported figure is roughly 950 litres (250 US gallons) a day. Because it does not depend on filters, the device needs few consumables.
Power is the other half of the problem in places without a grid. Kamen paired the purifier with a Stirling engine generator that can produce about a kilowatt of electricity from almost anything that burns, including dried cow dung. In principle, a village could make both clean water and some electricity from local fuel.
Field trials and the Coca-Cola partnership
The machines were tested in real settings over several years. A generator trial in Bangladesh in 2005 ran for six months and powered about 70 energy-efficient light bulbs. In 2006, two purifiers ran for a month in a village in Honduras, and in 2011 tests in five towns in Ghana were reported to show the device was effective and durable.
Scaling up required a partner with a global distribution network. In 2010 Kamen teamed up with Coca-Cola, and in 2012 the company, DEKA, the aid organisation Africare and the Inter-American Development Bank announced plans to bring the purifiers to rural communities in Latin America and Africa. As part of the arrangement Kamen developed the Coca-Cola Freestyle drink dispenser. The purifiers were eventually placed inside Coca-Cola’s EKOCENTER kiosks, small community hubs offering water, power and shop services, but Wikipedia reports that only about 150 units were deployed.
Why the safe-water problem is bigger than a machine
The scale of need is enormous. The World Health Organization estimates that in 2022 about 2.2 billion people still lacked safely managed drinking water, at least 1.7 billion used a source contaminated with faeces, and around 505,000 people a year die from diarrhoeal disease linked to contaminated drinking water.
Purification is only one step between a water source and a household. Someone has to run the machine, pay for fuel, fix it when it breaks, test the water, store it safely and get it to people’s homes. Early hand-built SlingShot prototypes reportedly cost around US$100,000 each; Kamen hoped mass production could bring the price down to a few thousand dollars, which still puts it beyond the budget of many villages without outside funding. Simpler options such as chlorination, ceramic filters, protected wells and piped supplies often do more good per dollar, which is why water experts tend to talk about systems and services rather than single inventions.
None of this makes the SlingShot a failure as engineering. It shows that a brilliant device is only the beginning, and that maintenance, financing and local ownership decide whether technology changes lives.
The SlingShot documentary
Paul Lazarus’s film follows Kamen’s effort to use his vapor compression distiller against the world’s water crisis, combining his personal story with the long development of the purifier and the search for partners. It is broadly an admiring portrait of an inventor who is famously persistent and curious. It is weaker as a guide to outcomes: the film was made while the project was still full of promise, so it naturally focuses on ambitions rather than measured results.
Watch it as a story about invention and persistence, then look at what happened next. As of 2020, Wikipedia noted that the purifier did not seem to be in commercial production or wide use.
Myths and takeaways
Myth: one invention can end the water crisis. No single device can. The most successful water programmes combine technology with funding, training and maintenance that continue for years.
Myth: distilled water is unhealthy to drink. Distilled water lacks minerals, but for most people a normal diet supplies them. Where water is unsafe, clean water of any kind is the priority.
Takeaway: If you want to support safe water, look for organisations that report on how long their systems keep working, not just how many they install.
Sources: Wikipedia: Slingshot (water purification system); Wikipedia: Dean Kamen; World Health Organization: Drinking-water fact sheet. Documentary SlingShot (2014) directed by Paul Lazarus.
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