Cities in Africa are creaking under the strain of tens of millions of extra residents. Unplanned urban settlements are growing at a pace that local authorities can barely keep track of, let alone provide services for.

The problem

We now have close to a billion people, around 1 in 7 of the world's population, living in these communities, usually without access to clean water, or sanitation. The result? A loss of dignity, lack of safety, particularly for women, frequent cholera outbreaks, widespread diarrhoeal disease and high child mortality.

We need to act fast, but this is a challenging problem to solve. Improving urban sanitation is particularly hard, and it’s not just about building toilets.

The challenges

Perhaps the biggest challenge is the absence of sewers. In the developed world, we can flush our toilets, removing waste without us worrying about it. Not so in urban slums, where sewers don't exist and are not likely to be built for decades to come without significant investment and political will. Without sewers, how do people get rid of the waste?

In Maputo, the capital of Mozambique, one of the world's poorest countries, 90 percent of residents do not have access to a sewer.

“Without sewers, how do people get rid of the waste?”

Take Teresa Nguila, 28, who lives in one of the poor “bairros” in Maputo. Her toilet was simply a hole lined with old car tires, and with sheets of corrugated iron for walls. "There was absolutely no privacy because it was situated right next to the street," she recalls. "The children always had to be accompanied because they were frightened that something could happen to them, for example that they would fall into the latrine."

This hole, which would flood every time it rained, spreading waste all over the compound, was shared between Teresa, her three children and five other families.

The solution

Teresa has recently become the proud user of a new sanitary block, which provides a safe, clean place for Teresa and her three children to go to the toilet in privacy. It is managed by the community, with each household paying a small fee to ensure it is properly maintained.

But the question remains: How does she get rid of the waste?

To help solve this problem, the private sector is playing a role. A number of entrepreneurs have set up businesses like ACADEC, which provide pit-emptying services in the narrow, unpaved alleys around Maputo’s city center, transporting waste to publicly managed treatment plants. Its not glamorous work, but it is crucial. And when the tank connected to Teresa's sanitation block fills up, she knows where to go to get it emptied.