Having no access to toilets has disastrous consequences for the spread of disease: some 6,000 children die every day from diarrhea caused by a lack of proper hygiene, according to international statistics.

"Excrement kills. It kills by the million" and is the leading cause of infection in the world, according to the Water Supply and Sanitation Collaborative Council, a Geneva-based organization promoting cooperation in water supply and sanitation.

One of the United Nations' Millennium Development Goals is to provide 1.75 billion people with access to their own toilets by 2015. That means 95,000 toilets will have to be installed per day if the goal is to be reached.

The biggest efforts will be required in India for 600 million people who live mostly in rural areas, in China for 400 million who live primarily in urban areas, and sub-Saharan Africa for 350 million people in both cities and the countryside.

But the issue of what kind of toilet to install is hotly debated.

Experts at the Stockholm Water Week conference this week explained that an ecological solution, where the urine is separated from the excrement and the materials are then recycled as fertilizer, is by far more preferable than flush toilets.

Flush toilets are considered convenient but they are seen as costly, more pollutant and they use too much water.

"Over a year, for each person some 400-500 litres of urine and 50 litres of faeces are flushed away with 15,000 litres of pure water," according to the Stockholm Environment Institute (SEI).

That is in addition to the 15,000 to 30,000 liters of water used every day for washing, laundry and cooking.

In wealthy western countries, used water is treated at the "end of the pipe" and pumped back into the waterways or the ground.

"Existing approaches to sanitation are not viable or affordable to the vast majority of people, neither do they offer people an approach towards a sustainable society," SEI said.

Ecological "dry" toilets are seen as a good alternative.

They have separate receptacles for liquids and solids and store them for later use as fertilizers. The excrement is dehydrated to create a compost, using for example ashes, sand or lime to help the decomposition process.

Such toilets already exist in northern Vietnam, in the Chinese province of Guangxi, in Guatemala, Mexico and Zimbabwe, but also in rich countries in Scandinavia, Germany and Switzerland.

But it is a challenge to get people to accept ecological toilets.

Firstly, they require more work than a flush toilet, with users throwing one of a number of materials on the discharge to speed the decomposition. The tanks also need to be emptied regularly. Others fear that an ecological toilet means a smelly toilet.

"Education is a big issue... A lot of people are hesitant," SEI expert Louise Dellstroem told AFP.

In Sweden, such toilets are commonly installed in summer homes and also in some urban areas where ecological projects are underway.

But for the most part in the western world, "it is difficult to recognize that the present system is not perfect," Swedish entrepreneur Bobby Bogdan Mrozowski said.

The head of his own company, BB Innovation and Co, Mrozowski has developed a system which collects the urine -- "the best fertilizer", he says -- but gets rid of the solids with a traditional flush, a system he markets in Scandinavia and a few other countries.

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