"They were threatening to evict me and all of a sudden I'm recognized by the state government and called to be an environmental educator. They want to organize regular visits to my house," said Bispo.

The slim 40-year-old said he built the house out of necessity after living most of his life with his parents in the giant Mare slum nearby. The foul-smelling channel and dirt-covered bayou near Guanabara Bay contrast with Rio's famous sandy beaches just a few miles (kms) away.

The house can be seen from Rio's Red Line thoroughfare on the way to the international airport, and motorists often slow down to take a look at or photograph the white squat structure. A red carpet covers a jetty where Bispo moors his dinghy, and an open platform serves as a parking spot for his rusty 1982 Chevrolet.

"I don't have money to repair it and kids were messing with it in the street, so it's safer here," he said.

Bispo, who earns a living by doing occasional repair and construction work, said he spent about US$170 to build the house, mainly on cement and roof material. The rest came from construction waste and furniture he found at dump sites.

Marilene Ramos, head of the Rio state superintendency for rivers and lakes, said the government at first feared Bispo's project would encourage others to build on the water and further clog the channel.

But Minc has come up with an idea. The floating home will be moored to a filtering barrier in the Cunha channel that removes garbage.

"His demonstrative project has synergy with our ecological barrier, which gets many visits, particularly from schools. It can be part of environmental education support," Ramos said.

Many of Rio's 600-plus slums have no running water, sewage or garbage removal service, which causes massive pollution around them, converting rivers in dirty, smelly streams that get clogged during heavy rains and cause flooding.

Bispo said the channel's stench doesn't bother him.

"I've spent 40 years living alongside this stream, so it's like working on a garbage truck -- you get used to it. Also the water only smells when you mess with it, if a boat passes or tide changes," Bispo said.