Every March 22nd is designated as World Water Day, with the goal of “focusing attention on the importance of freshwater and advocating for the sustainable management of freshwater resources.” This year’s theme is “Water for Cities: Responding to the Urban Challenge,” in recognition of the fact that half the world’s population now lives in an urban area. Nearly 40% of this urban expansion occurs in slums, where the infrastructure is insufficient for delivering clean water to residents and properly handling sewage.

I addressed the sanitation aspect of urban growth a few months ago in “From the Broad Street Pump to Flying Toilets: Cities’ Need for Sanitation,” so today I’ll add a few items on the issue of clean water for urbanites. Here are a few facts and figures from the UN-Water Decade Programme on Advocacy and Communication:

• Between 1998 and 2008, 1052 million urban dwellers gained access to improved drinking water … However, the urban population in that period grew by 1089 million people and thus undermined the progress.
• 27% of the urban dwellers in the developing world do not have access to piped water at home.
• The urban poor pay up to 50 times more for a litre of water than their richer neighbours, since they often have to buy their water from private vendors.
• Contaminated drinking water results in cholera epidemics, faecal-oral diseases such as diarrhoea, and outbreaks of malaria.

One of the problems is water leakage:

• Leakage – loss – rates of 50% are not uncommon in urban distribution systems.
• Some 250 to 500 million m³ of drinking water gets lost in many mega cities each year.
• Saving this amount could provide an additional 10 to 20 million people with drinking water in each mega city.

Climate change is making an already challenging task even more difficult – and urgent. Drought and saltwater intrusion threaten the overall availability of water, while flooding can disrupt and contaminate water supplies in affected communities.

This UN media brief includes examples of how several cities – from Accra, Ghana, to Zaragoza, Spain – are addressing their water challenges. Approaches include improving water access, minimizing leakage, and managing demand.