Scientist Murendeni Mafumo and his water purification business Kusini Water wowed judges to win the annual Pitch&Polish startup competition in Joburg tonight.

Mafumo’s technology is a low cost membrane that can take rainwater or ground water and, using a process of osmosis, clean it ready for drinking. The system is entirely designed and built in South Africa, and a key ingredient of the system – whose top secret formula is currently awaiting a patent – is crushed macadamia nuts. Crushed nuts are used for the activated carbon filter which removes bad tastes and smells, before the water is pushed on to the nanotech membrane.

The pumps that push water through the membrane are solar powered, and similar systems have been trialled by MIT researchers in South America.

Mafumo says that his membrane is currently being tested in three different pilot programmes, including coffee shops which are using it to purify rainwater for drinking, a shopping mall which recycling waste water for irrigation and car washing and – in the most ambitious use – a low cost desalination plant in Namibia.

Mafumo is looking for more funding to further develop Kusini Water’s solution into a product that can be sold to rural municipalities.

By far South Africa’s most exuberant competition for entrepreneurs, Pitch&Polish, rounded off its 2016 tour of the country tonight in Joburg. Three finalists took to the stage in a Dragon’s Den-style pitch-off during which they were grilled about finances and the state of their businesses.

Pitch&Polish, which is put together by startup accelerator Raizcorp, is to help entrepreneurs develop their million rand requests for investors and condense the highlights of their business down to three minutes. The top prize is R60 000, but previous winners and runners-up, including TenderPoint from 2014, have walked away with far bigger sums in backing from the investors in the audience.

Adam is the Editorial Director at htxt media. He has been writing about technology for almost two full decades now. In a previous life, he was the editor of PC Format and Digital Camera Shopper in the UK, before going on to work as a freelance journalist for seven years. His work has appeared in or on Stuff, The Guardian, Linux Format, TechRadar, Wired.co.uk, PC Gamer, Green Futures, The Journalist, The Ecologist and The Review. Adam moved to South Africa in 2012 and loves 3D printers, MakerFairs and tech hubs. He hates seafood. None of his friends remember this when cooking.