A general view of Mukuru Kwa Ruben, an informal settlement in Nairobi, Kenya
Soiled: tonnes of waste gets dumped into the streets and waterways of Kenya’s informal settlements © Siegfried Modola

On a muddy, rubbish-strewn walkway in Nairobi’s Mukuru kwa Ruben slum, Esther Munyiva is peering at a small, bulging, plastic bag on the ground. That, she points out, is a “flying toilet” after it has landed.

“Look, this is the way we were using toilets before. You can’t [pick it up] with your bare hand because it is full of waste. They throw [them] at night while you are fast asleep … we are used to it.”

The inability to deal with human waste has long been one of the most distressing aspects of living in the slums of Nairobi, where 200 informal settlements house an estimated two-thirds of the city’s 3.5m people. Every year 4m tonnes of waste from Kenya’s slums are dumped into waterways and the soil.

For those who choose not to use plastic bags, pit latrines offer little extra comfort. The raised loo blocks topped by corrugated metal sheeting, with pits dug out for the waste, regularly overflow during the rainy season. For the rest of the year, waste water and disease seep into the soil and the latrines are regularly so badly maintained that “flying toilets” hold more appeal.

“They give you the key, but the toilet is full, so there is nowhere to step. They don’t take care of the toilets, so people use paper and polythene at home and just throw it,” says one resident.

It is part of a much wider, global problem. The World Health Organisation says 2.5bn people lack adequate sanitation. This undermines development and spreads illness – an estimated 1.8m die every year from diarrhoeal diseases, accounting for the vast majority of deaths of children under five.

The scale of this problem first absorbed social entrepreneur David Auerbach during a spell in China. Later, he did an MBA at Massachusetts Institute of Technology and co-founded Sanergy in an attempt to solve it. The resulting idea sets out to turn human waste into gold.

By creating a network of low-cost franchised toilets, operated on a pay-per-use basis by resident micro-entrepreneurs throughout the slum, the Sanergy team can collect the waste and generate huge amounts of organic fertiliser with it, selling it to farmers at a profit.

“It is a market-based approach. It is all a function of the amount of waste we collect,” says Auerbach. So far, the company has sold 202 toilet blocks. That adds up to four tonnes of solid waste a day, but he says this could reach 10 tonnes a day by the end of the year.

He estimates the project – which is half-funded by grants and private capital – will break even once it has sold 1,000 blocks, but the idea is to create something that can scale up.

A simple design separates collected liquid and solid waste into two sealed plastic containers in the stall. Instead of flushing with water, residents pile on sawdust, saving 150,000 litres of water a year for each stall. Sanergy sells each prefabricated bright blue Fresh Life toilet block, painted with cheery yellow sunbursts, at cost price for Ks50,000 ($575) – a hefty sum given that it is more than half the average annual gross domestic product per capita.

Munyiva, who borrowed money from a local women’s microfinance organisation to buy one of Sanergy’s first stalls last year, says she has already repaid her debt in instalments. “The toilet is now mine,” she beams, saying she charges out usage at Ks3 a go for adults and Ks2 for children.

Mery Kioko, owner of several Fresh Life toilets
Flush with success: a Fresh Life operator © Siegfried Modola

“I love this business … it has brought me somewhere,” says the 55-year-old mother of six. She takes Ks350 a day. “You [don’t have to] sleep with hunger when you have this. I’m taken seriously. I want to buy another one.”

A production plant on the edge of the slum makes up to eight blocks a week with local cement, each one equipped with a starter pack that includes toilet roll, a solar lantern and a mop, plus training in bookkeeping and branding, which Sanergy believes is key to maintaining hygiene standards and encouraging customers to keep coming back.

Munyiva and other Fresh Life operators are required to keep the blocks spotless or risk having them bolted shut. At the same time, the company tries to tackle the stigma of the messy business.

“We throw a block party for the opening of the toilet, with a sound system, face painting for the kids, balloons. Fresh Life operators love it – it means a lot to be leaders in improving their community,” says Nicole Parisi-Smith, Sanergy communications manager.

Each day, the company’s “frontline team” removes the waste from the blocks and carts it out of the slum. It is piled into covered vats in an open-air yard and starts to decompose, turning into organic fertiliser within eight months to be sold to local farmers, who grow everything from vegetables to flowers.

The liquid waste, for now, is removed by truck and released into the sewage system, but the company is working on a way to recycle this waste too. Farmers are still testing quite how nutrient-rich and fertile the organic compost is. The key will be to generate enough waste and secure enough deals to sustain and grow the scheme.

But while profit is an important driver of the project, it is a necessary ingredient rather than the lure. “If we were in it to make money there is a ton of other things we could do,” says Auerbach. “We are in it to solve a massive social problem.”

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