The canal at Tamatave is the biggest in Madagascar, moving through a stunning landscape of sweeping valleys into the ocean. But for Hamady Rassanirina and his family the waterway has been a source of misery.
Each of his three children has been acutely ill with stomach diseases from the pollution caused by industrial and domestic waste that has turned the water into a semi-opaque grey sludge. Sons and daughters of neighbours have faced the same predicament, some have died.
"Why is it that we are surrounded by the sea and we have so many rivers but we cannot have clean water?," he asked. "It is the same with all the minerals we are supposed to have. What is the good of having all these treasures underground when we have people dying because they are so poor?"
In Madagascar, as elsewhere in so many places in the Third World, poverty and poor sanitation often add up to death. Across the globe more than a billion people do not have access to clean water and the diseases they are exposed to take a heavy toll, especially among the very young.
The numbers of people affected are expected to rise internationally to three billion in the next two decades. Yet, say aid groups, most people in the affluent West are unaware of the seriousness of the problem so they are using UN World Water Day to launch a drive to raise awareness.
The End Water Poverty campaign organised by, among others, WaterAid, Tear Fund, and the Dutch group Simavi says: "The international effort on sanitation and water is in disarray, poverty is not being tackled. Governments must be told that it is morally and economically indefensible to preach poverty reduction but leave millions of people to live in squalor and disease."
Standing beside the fetid canal, Mr Rassanirina's 33-year-old wife Patricia said: "There are a thousand families living around here and we have diarrhoea and malaria here, many children are sick all the time. The nearest place we can go for treatment is the Lutheran Hospital and that is an hour's walk away."
The community along the Pangalanes canal will be helped by a project organised by WaterAid, the aim of which is to provide clean water at the traditional neighbourhood water pump, and give instructions in basic hygiene.
It is one of a number of similar projects with a number of international charities. Yet the $20m (£10m) being spent overall is $97m less than is needed to meet the Millenium Development Goals signed up to by the Malagasy government.
But Madagascar should not be one of the poorest countries in the world, with 72 per cent of the population below the poverty line. It has some of the richest untapped deposits of gemstones in the world - sapphires, rubies, garnets, amethysts and acquamarines. There are other minerals including titanium, aluminium and graphite. And there is offshore oil.
It is also one of the dozen most important countries for biodiversity on the planet, although decades of depredation has wiped out almost 90 per cent of rainforest and dozens of species of flora and fauna. Some of it is blamed on strip mining and the rest ontavy, the practice of slash and burn by the rural poor in which miles of verdant land are left exhausted and barren.
The unique fauna and flora attracts a rising stream of wealthy ecotourists from Europe and North America. Yet very little of their money trickles down to the dispossessed rural poor. At the village of Jirama, Juliette Vavey works 11 hours a day on a farm to provide for her eight children. She then has to walk 90 minutes to fetch water. " I am exhausted all the time," she said. "I worry about my children because they are sick so often. But I cannot spend more time with them because I have to work to get food."
Brother Edwin, a member of the Freres Montfort De Saint Gabriel (FSG) Order, at Tamatave, has helped to found a number of water projects in the area. "What has happened here is very sad," he said. "This is a vibrant country with huge potential. Yet you see so much hardship."
The actor and comedian Sean Hughes, who recently visited Madagascar with WaterAid said: "All we can hope to do is make the lives of the people here just a bit better but the international community must be made aware of what is at stake."