Nairobi, Kenya - If you have ever attended a music festival, chances are you are familiar with the dreaded panic of looking for the nearest bathroom when nature calls. Now imagine that same panic, but this time being inside your own home.
However, instead of walking down your corridor to the bathroom, you have to walk a few blocks, perhaps in the dark, to the nearest toilet - a hole in the ground, reeking with stale urine and sometimes full of waste, shared by a dozen other families. This is the reality for many slum dwellers in Kenya.
Unsurprisingly, many residents don't bother with the walk. For privacy and expediency, they opt to relieve themselves using plastic bags and then throw them as far away as possible from their homes: a phenomenon known as the "flying toilets".
Landlords are reluctant to build more toilets to keep up with fast-expanding informal settlements, because in the space it takes to build a toilet they could build a room and earn more money, said Stella Kitonga, deputy project manager at Peepoople, an NGO that operates in Nairobi slums.
Concerned with community hygiene and the potential of "flying toilets" in the spread of diseases, Peepoople has come up with a novel approach to tackle the problem in Silanga, a village in Kibera, Kenya's biggest slum: a self-sanitising, biodegradable bag known as "Peepoo" that people can use in their homes.
Incredibly, Peepoos meet the World Health Organisation's requirement for hygiene and disease prevention, as each contain five grams of urea, which breaks down waste into ammonia and carbonate.
The bags have an inner and outer layer. The inner layer has a wide tube to keep hands clean when holding or closing. The outer layer then pulls up over the inner layer and ties into a knot to prevent flies and small animals from coming to contact with it. The odour can be contained for up to 24 hours.
For women living in the slums, there is an added element of security in using the Peepoo in the safety of their own homes.
"A number of rape cases have been reported when women had to go outside the home to look for sanitation facilities. But we have come to understand that since the Peepoo was introduced, there has been a reduction of rape crime in the Silanga village," says Mika Mitoko, project manager at Peepoople.
The bags, which are subsidised by donors, are sold for 3 Kenyan shillings ($0.03) each.
The bags' small size means they can also be carried to be used elsewhere. Users can opt to keep the waste and use it as garden fertiliser, or the bags can be dropped at a collection point for a reimbursement of 1 shilling ($0.01) per bag.
"I didn't have a regular job before the Peepoos were introduced, but I saw an opportunity when people did not want to drop off the bags themselves."
- Mama Lucy, entrepreneur
The reimbursement is intended to discourage people from dumping the bags, but it has had the unintended effect of creating jobs. For those reluctant to carry the waste and drop it off at the designated place, a collection service now exists.
Mama Lucy, a young mother of three, makes her living by collecting the used Peepoo bags from her network of neighbours and friends. She then pockets the reimbursement fees.
"I didn't have a regular job before the Peepoos were introduced, but I saw an opportunity when people did not want to drop off the bags themselves," she said, handing in a bucket of bags at the drop-off point.
"Now, I do two rounds a day to pick Peepoos from people's houses. On a good week I earn about a thousand shillings ($11)."
Originally a pilot project introduced in 2010, Peepoo is now at an official launch stage, ready to be implemented in other parts of Kibera.
However, the business of tackling slum waste is not just limited to NGOs. The private sector is also getting involved and turning a profit.
Sanergy, a company founded by MIT business school graduates whose name combines the words "santiation" and "energy", aims to build a dense network of low-cost sanitation centres named Fresh Life, and distribute them by franchising local entrepreneurs to run as small businesses.
Sanergy then collects the waste from the toilets and converts it to useful products such as biogas and organic fertiliser, which is sold to a number of co-operatives.
They have partnered up with KIVA, a microfinancing organisation that provides small loans to entrepreneurs who wish to purchase a Fresh Life toilet.
According to Sanergy co-founder David Auerback, the business model was simple enough: research showed a need and a willingness to pay "three to five Kenyan shillings ($0.03-0.05) to use sanitation facilities - so we came in at that price".
Fresh Life facility managers boost profit by selling additional products such as toilet paper and sanitary pads.
Auerback added that business is so profitable that many of the entrepreneurs running Fresh Life toilets are doubling down and purchasing another - proof, he says, that dealing in slum waste is a "viable business".
Follow Laila Ali on Twitter: @LailaInNairobi