Some recent water pollution-related incidents have roused serious concerns across China. The latest one occurred in Lanzhou, Gansu province, on April 11: excessive levels of benzene were detected in the city's tap water. Local authorities later said crude oil leaking from a pipeline had contaminated tap water supplied to 2.4 million people in the city. Benzene levels in the water returned to normal only on April 14.
The Lanzhou case is just one example of the looming water crisis in China. In 2011, water in more than half of China's largest lakes and rivers was deemed unfit for human consumption.
Last year, the Ministry of Environmental Protection conceded that, "toxic and hazardous chemical pollution has caused many environmental disasters, cutting off drinking water supplies...leading to severe health and social problems'."
Worldwide, the water crisis is even more alarming, but it hasn't drawn enough attention. In 2012, the UN announced that the Millennium Development Goals' target of halving the number of people without sustainable access to safe drinking water had been achieved well ahead of schedule, with only 783 million people still lacking access to clean water.
But the Third World Center for Water Management estimates that at least 3 billion people worldwide still drink water of dubious quality. AquaFed, which represents private water companies, puts this figure at 3.4 billion - nearly half the world's population. This suggests that the UN's declaration of victory was premature.
India's situation is worrisome, with the state-run Central Pollution Control Board reporting last year that nearly half of the country's 445 rivers are too polluted in terms of biochemical oxygen demand (an indicator of the organic quality of water) and coliform bacteria to be consumed. If other pollutants - such as nitrates, fluorides, pesticides and heavy metals - were considered, the figure would be significantly higher.
Likewise, Pakistan's National Assembly was informed last year that 72 per cent of the samples collected from the country's water supply systems were unfit for human consumption, with 77 per cent of the groundwater in urban areas (and 86 per cent in rural areas) deemed hazardous.
In Nepal, the Department of Water Supply and Sewerage has said 85 per cent of its traditional water supply systems are seriously contaminated with bacteria, iron, manganese and ammonia.
And in Mexico, 90 per cent of the country's nearly 25,000 water utilities were operating in a state of bankruptcy in 2013.
The problem with international organisations' approach is that they conflate the vague notion of "improved water sources" with genuinely clean, safe drinking water. In the same way, they have diluted the goal of "improved sanitation" - the process of collecting, treating and safely discharging wastewater - by applying it to indoor toilets in people's homes.
This glosses over a major discrepancy between sanitation and adequate wastewater management.
While nearly 90 per cent of the households in the National Capital Region of India (Delhi and its adjoining areas) are said to have adequate sanitation, because they have indoor toilets, nearly all of the untreated wastewater from the NCR is discharged into the Yamuna River - a source of drinking water for cities downstream.
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 per cent 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 per cent 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 per cent. The ministry also found that only 12 per cent 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 recognise 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 fulfil 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.