More than 2.6 billion people - over 40 per cent of the world's population - do not have basic sanitation, and more than one billion people still use unsafe sources of drinking water, warns a major report released today by WHO (the World Health Organization) and UNICEF.

Entitled Meeting the Millennium Development Goals drinking water and sanitation target - A mid-term assessment of progress, the report details the progress of individual countries, regions, and the world as a whole between the MDG baseline year of 1990 and the half-way mark of 2002. It makes two significant predictions on reaching the 2015 goals, based on progress to date:

- The global sanitation target will be missed by a staggering half a billion people - most of them in rural Africa and Asia - allowing waste and disease to spread, killing millions of children and leaving millions more on the brink of survival.

- The world is on track to meet the drinking water target, but population growth may outstrip improvements, with 800 million people still drinking unsafe water by 2015.

This severe human and economic toll could be prevented by closing the gap between urban and rural populations and by providing simple hygiene education, say UNICEF and WHO.

The agencies warned that a global trend towards urbanization is marginalising the rural poor and putting huge strain on basic services in cities. As a result, families living in rural villages and urban slums are being trapped in a cycle of ill-health and poverty. Children are always the first to suffer from the burden of disease caused by dirty water and poor hygiene, while the wider impact of unhygienic environments drags back economic progress and erodes good governance.

"Around the world millions of children are being born into a silent emergency of simple needs," says Carol Bellamy, UNICEF's Executive Director. "The growing disparity between the haves and the have nots in terms of access to basic services is killing around 4000 children every day and underlies many more of the 10 million child deaths each year. We have to act now to close this gap or the death toll will certainly rise."

"Water and sanitation are among the most important determinants of public health. They are amongst the top of WHO's list of components of primary health care. Wherever people achieve reliable access to safe drinking-water and adequate sanitation they have won a major battle against a wide range of diseases." says WHO Director-General Dr LEE Jong-wook.

Developing regions of the world, such as sub-Saharan Africa, are most at risk. But the report also highlights some worrying trends in the industrialised regions, where coverage figures for clean water and basic sanitation facilities are estimated to have decreased by 2 per cent between 1990 and 2002. In the former Soviet Union, only 83 per cent had access to adequate sanitation facilities. With economic and population pressures growing, these percentages could decrease.

The consequences of inaction today are severe, according to WHO and UNICEF. Diarrhoeal disease currently takes the lives of 1.8 million people each year - most of them children under five - with millions more left permanently debilitated. Over 40 billion work hours are lost in Africa to the need to fetch drinking water. And many children, particularly girls, are prevented from going to school for want of latrines, squandering their intellectual and economic potential.

Reversing this trend and moving towards universal coverage for water and sanitation will take more than money, said Bellamy and Lee. National policies based on the principle of "some for all" rather than "all for some" have been the key to improvements in many countries. And at the local level, resources have to be retargeted to include the poorest communities, with local government and the private sector co-operating to bring affordable solutions.

"To meet the 2015 targets, countries need to create the political will and resources to serve a billion new urban dwellers, and reduce by almost 1 billion the number of rural dwellers without access to adequate sanitation facilities - otherwise we risk leaving millions, if not billions, out of the development process," says Dr Lee.

WHO and UNICEF say the report, which is the first in a series looking at progress in water and sanitation coverage, should be a wake up call to all global leaders. Every country still has work to do to eliminate disparities in basic services and the data shows clearly how that can be done before the MGD deadline of 2015.

There are also very encouraging signs. Great gains in water and sanitation coverage have been made against considerable odds in many countries. This progress came as a direct result of political prioritisation and a drive to find locally effective solutions.

"This report is important because it proves that significant improvements are possible in a short space of time, even in the poorest countries." says Ms Bellamy. "By identifying trends now, and committing to course corrections, we have a real opportunity to ensure that by 2015 these basic essentials of life are available to all."