Composting toilets key to global sanitation, say scientists

NewScientist.com news service

Giving large sewer systems to communities in the developing world could be disastrous for them and their environments, sanitation scientists are telling the World Water Forum in Kyoto, Japan. Their advice flies in the face of United Nations targets to hook up more than a billion people to sewers in the next decade.

Government ministers and water experts are meeting to hammer out plans for meeting the UN target of halving the number of people in the world who lack clean drinking water and modern sanitation by 2015. Allowing for population growth, that means connecting 400,000 people every day for the next 12 years.

But scientists at the forum say installing conventional sewer systems that empty into rivers could create a public health disaster, rather than solving one. Instead, they want to recycle sewage from poor villages and shanty towns so it can fertilise fields.

"Conventional sewer systems are just not the right answer," said Bengt Johansson, of the Swedish International Development Agency. "They are very expensive; they pollute rivers; they use a lot of water for flushing that could be set aside for drinking; and they deprive farm soils of the nutrients in sewage."

The UN Environment Programme agrees. "Nobody planning these sewers is thinking about the pollution," said a spokesman.

Compost heap

The solution, say aid agency experts, is "ecological sanitation", or EcoSan. This involves composting sewage and is cheap, water efficient and non-polluting. "It is not a second best," said Johansson. "I have an EcoSan system in my summer house outside Stockholm. It works very well."

And Michael Rouse, formerly the UK's chief drinking water inspector, recently said that if Britain were planning sewage disposal from scratch today, "we wouldn't flush it away - we would collect the solids and compost it".

The Japan Toilet Association is displaying examples of EcoSan technology here. Some are toilets that store and compost the sewage. Some are community systems that separate urine, faeces and washing water and recycle them separately, irrigating and fertilising fields. Some even ferment sewage to make biogas for cooking.

But despite a host of innovative technologies for supplying water and handling sewage, the meeting is dominated by water industrialists pushing for extra investment in large infrastructure projects.

In addition to large sewage projects, they are pushing for a revival in the construction of large dams, which is certain to be controversial. Many such projects have been on hold since a World Bank moratorium imposed in the mid-1990s, but that moratorium was lifted in February.