Water is the most vital necessity for all forms of life. However, it is increasingly becoming a scarce resource. Over the last century, the world's population has tripled, while the use of water increased sixfold. >> World Water Day 2011 . Photo:ILO/Crozet M.

Today, one in two people on the planet live in a city. Due to natural increase or to rural-to-urban migration, the urban population grows by 2 persons every second. Nearly 40% of the world's urban expansion is growing slums. Between 2005-2020 the world's slums are estimated to increase by 27 million people per year. >> World Water Day 2011 . Photo:ILO/Crozet M.

Cities are complicated to manage: different approaches are needed for different types of urban environments. But cities also provide the best opportunity to improve livelihoods and infrastructure development, including water and waste services. >> World Water Day 2011 . Photo:ILO/Voeten T.

827.6 million people live in slums often lacking adequate drinking water and sanitation facilities. Massive growth of cities brings along several challenges related to water quality issues and sanitation. Investments in infrastructure have not kept up with the rate of urbanization and while water and waste services show significant underinvestment. >> World Water Day 2011 . Photo:ILO/Crozet M.

Evidence shows that water resources will be significantly affected by climate change, both in quantity and quality, particularly through the impact of floods, droughts, or extreme events. The effect of climate change will also mean more complex operations, disrupted services and increased cost for water and wastewater services. In addition, climate change and disasters will result in increased migration to urban areas, increasing the demand on urban systems. >> World Water Day 2011 . Photo:ILO/Crozet M.

Piped water coverage is declining in many settings, only 27% of urban dwellers in the developing world have access to piped water and the poor people get the worst services, yet paying the highest water prices. >> World Water Day 2011 . Photo:ILO/Crozet M.

About a quarter of all urban dwellers, 794 million in total, do not have access to improved sanitation facilities. The situation in these urban areas leads to water related diseases such as diarrhoea, malaria and cholera epidemics. >> World Water Day 2011 . Photo:ILO/Crozet M.

90% of all waste water in developing countries is discharged untreated, polluting rivers, lakes and seas. Discharge of untreated wastewater shifts problems to downstream areas. Every year insufficient water and inadequate sanitation and hygiene contribute to the deaths of 1.5 million children and about 42,000 people die every week from diseases related to low water quality and inadequate sanitation. >> World Water Day 2011 . Photo:ILO/Deloche P.

Women and children carry most of the supply burden when access to water is not guaranteed. They are forced to spend a large portion of their day fetching water from sources that are often far away and contaminated. A lack of access to water can raise the value of children's time in non-schooling activities, as children are needed to undertake responsibility for water collection or to help cover the cost of purchasing water. >> World Water Day 2011 . Photo:ILO/Crozet M.

Many children in the developing world, in particular girls, are denied the right to an education because schools lack adequate toilet facilities. Of the 120 million school-age children not in school, the majority are girls. Schools with decent toilet facilities enable children, especially girls reaching puberty, to remain in the educational system. >> World Water Day 2011 . Photo:ILO/Crozet M.

Well-managed wastewater can minimize environmental and downstream pollution and lead to improved food security, health and economic development. Green jobs can be created through improving water-related infrastructure, the expansion of jobs in the sanitation sector, the provision of piped water, the construction of dams, promotion of recycling for agricultural purposes as well as irrigation systems and restoration of water sources such as rivers, lakes, mangrove and inland wetlands. >> World Water Day 2011 . Photo:ILO/Crozet M.

Water management and supply are critical to the well-being of citizens all over the world and reforms have to take into account the social dimensions of the issue. Since employers and workers are actively engaged in water supply, the ILO is working with governments to address these issues through worker and employer participation in water utility reforms which bring safe water to communities, generate employment, prevent child labour, and which are also environmentally-friendly. >> World Water Day 2011 . Photo:ILO/Crozet M.