The world is well on its way to meeting the Millennium Development Goal to halve by 2015 the proportion of people who in 1990 had no sustainable access to safe drinking water (Nature 483, 128–129; 2012). But more resources are still needed to improve water quality in China, particularly in rural areas.

According to a report released last month by the World Health Organization (WHO) and the United Nations Children's Fund (UNICEF), China contributed an estimated 457 million people to the 2 billion who by 2010 had access to improved water sources.

However, these 'improved' sources (a piped supply or borehole, for example, as opposed to a stream or unprotected well) do not always supply safe water, as judged by China's national standards for water quality.

Although 85% of China's rural population (605 million people) had access to improved water sources in 2010, only around one-quarter of these sources would be considered safe by national standards (R. Zhang et al. J. Environ. Health 26, 3–5; 2009). By comparison with 1990 figures, this implies that only about 35 million people in rural China had gained access to safe water by 2010. For piped urban water, however, almost 91% of the water supply complied with chemical and microbial standards (J. Zhang et al. J. Shenyang Agric. Univ. 34, 460–463; 2003), so roughly 295 million urban Chinese gained access to safe water over the same period.

The total Chinese population with access to safe water is therefore 330 million at most. This is about 127 million fewer people than estimated by the WHO/UNICEF report, a figure that is roughly equivalent to the population of Japan.