According to the World Water Assessment Program, half of the world’s population now lives in cities, up from less than 15% in 1900. The world’s metropolitan regions face distinct water management issues, but they also bring some opportunities.
Localized sources are not always able to provide high-volume water demand when millions of people reside in close proximity. In increasingly urbanizing areas, good management of regional watersheds to maintain a sufficient water supply can be difficult—both technically and politically.
Many urban centers around the world are developing at an alarming rate, and unrestrained expansion is generating slum communities devoid of water infrastructure. Untreated human waste is disposed of in open ditches, streams, and rivers where basic sanitation is unavailable. These waste products are a substantial health risk, and they significantly promote the development of waterborne and sanitation-related disorders such as diarrhea and parasite infections.
These responsibilities are borne mostly by the poor. There are over 180 million slum dwellers worldwide who do not have access to safe drinking water. Child mortality rates are several times greater in places with inadequate water and sanitation services than in those with sufficient water and sanitation services.
Local authority initiatives are frequently focused on creating community toilet facilities and establishing waste treatment infrastructure, as well as ensuring arrangements for clean water supply in underserved districts. Those who do not have access to clean water must continue to drink. They usually resort to contaminated water, which causes a slew of health issues, or pay fees to bottled, trucked, or other private water sellers—at prices that are several times higher than those of city inhabitants who benefit from piped-water infrastructure.
However, many metropolitan piped-water systems have their own set of issues. Water loss from aging or poorly maintained pipelines is common—more than 25% in Mexico City, for example—an intolerable waste of an often-scarce resource. Furthermore, if the pressures in these defective pipes are low enough, they may be polluted by sewage or other untreated water influx.
These dense populations present more than simply difficulties. They also give a chance to more efficiently supply clean, treated water to many millions of people who might otherwise be in hard-to-reach areas. Proper sanitation systems may also be easier to construct and maintain when the distances involved are not prohibitively long. For these reasons, urban inhabitants in most of the developing world are often more likely than rural counterparts to have access to clean water and appropriate sanitation facilities.