Likewise, Mexico City is considered to have a high level of sanitation, even though it transports untreated wastewater, loaded with pathogens and toxic chemicals, to the Mezquital Valley to be used to irrigate crops.

The Third World Center for Water Management estimates that only about 10-12 percent of domestic and industrial wastewater generated in Latin America is properly treated. The situation is probably similar in developing countries in Asia and perhaps worse in Africa.

In 2011, a survey by the Central Pollution Control Board of India showed that only 160 of 8,000 towns had a sewerage system as well as a sewage-treatment plant. Most government-owned sewage plants are non-functional or closed most of the time, owing to bad management, poor maintenance, faulty design, lack of regular electricity supply, and absent, untrained or uncaring employees.

Similarly, China's Ministry of Housing and Urban-Rural Development said in 2012 that while 640 of 647 cities and about 73 percent of counties had wastewater-treatment facilities, 377 plants built in the course of one year did not meet national requirements, and that the average operating efficiency was less than 60 percent. The ministry also found that only 12 percent of the plants met the country's Grade 1A standards.

This does not reflect a dearth of knowledge, technology or expertise. Nor can it be blamed on a lack of investment. China spent $112.4 billion on water infrastructure in the 2006-2011 period, and India has channeled massive amounts of public funds toward cleaning up the Yamuna River. Yet both countries' water supplies remain highly polluted.

The world's water and sanitation challenges are by no means insurmountable. But dealing with them requires sustained political will, with governments building strong water institutions and ensuring that public funds are used as effectively as possible. At the same time, the public must recognize that it can have better water services if it is willing to contribute through taxes, tariffs and transfers.

For their part, the media must stress the benefits of functional water delivery and wastewater management systems - and hold politicians and bureaucrats accountable if they fail to fulfill their duties. And water professionals need to shift their focus from providing more water to providing safe water more sustainably.

Since failing to address the water challenge would, within a generation, bring about a global crisis of unprecedented proportions, such efforts could not be more urgent.

Asit K. Biswas is the founder and president of the Third World Center for Water Management in Mexico and distinguished visiting professor at the Lee Kuan Yew School for Public Policy in Singapore, and Peter Brabeck-Letmathe is chairman of Nestlé and the global public-private partnership 2030 Water Resources Group.

(China Daily 04/17/2014 page9)