Not only are hidden street corners used as make-shift toilets, even walls of residential homes are hit.
If it is understandable to go behind a tree in a rural setting where it might be hard to find a toilet, in Libreville, an urban city of about half a million people, the habit is causing anguish among residents.
Eugenie Assoumou Mengue knows what it is like to live in a house which has walls that are regularly sprayed.
"We're suffering, it's hellish. People come and urinate here and we get the smells that make us really sick," she said, indicating an area on her walls where cement was flaking off.
Her efforts to fend off the unwelcomed visitors have come to nothing. "They insult me. I hope Regis can motivate them to stop," said Assoumou Mengue, who came outside to see Divassa spray-paint the slogan "Stop urinating!" on one of the walls.
Divassa, an artist, cinema set designer and rap artist, has teamed up with his partner "Blatino" to target areas in Libreville that are thick with filth, spraying slogans or full-fledged frescoes to get people to stop think twice.
"Graffiti is like a picture. If people see something beautiful on the wall, they won't come and pee against it," said Divassa. "Street art is something young people appreciate."
For Divassa, street art is a political act, a kind of rebellion that can serve to raise public awareness about not just the toilet issue, but also the general filth problem plaguing Libreville.
Besides the struggle to get people to use toilets, uncleared waste has also become a bugbear for Libreville's citizens and regularly hits the national headlines.
In nearly every neighbourhood in the city, piles of rubbish can be seen rising metres high up near bins that no one empties, stewing under suffocating heat and emitting putrid smells.
The rubbish "even holds up the traffic because it overflows onto the road and cars can't get past," said one shoe seller from his tiny shop.
"The town hall has to do something," he said. Each month he pays a cleanliness tax of 24,000 FCFA ($50) "without knowing what it's for."
Another shopkeeper who came to greet Regis said he was disgusted by the rubbish lining the streets outside his food store.
"We can't breathe anymore. The bins are never emptied and with heavy rainfall it overflows through the whole city and makes people sick."
Libreville's unpopular mayor Jean-Francois Ntoutoume Emane, who will not run again in the November elections, is facing widespread criticism and blamed for not honouring his engagements with the organisation responsible for collecting household waste.
Responding recently to questions from deputies and senators, the mayor acknowledged that the rubbish issue is a recurring one, but he refused to shoulder the blame.
Faced with political inaction, Divassa hopes that his street art around the city will help raise public awareness and help to turn the situation around.
"All this is the state's fault. But who is the state? The state is you and me. The state is us."