We disagree with aspects of Tao Tao and Kunlun Xin's plan for sustainably producing China's drinking water (Nature 511, 527–528; 2014).

In our view, the country should continue to improve its mains-water infrastructure: upgraded pipework is essential to its urbanization strategy (see X. Bai et al. Nature 509, 158–160; 2014).

Projects are already under way for recycling water and cleaning water sources. In Beijing, for example, recycled water is used in industrial processes, for replenishing rivers and lakes, and for irrigation and domestic purposes. And Yuanping city in Shanxi province now has a purification plant for industrial wastewater.

We question the feasibility of installing household water purifiers, a core feature of the authors' plan. Each would cost around 1,500 renminbi (US$244), which amounts to 645 billion renminbi for all the families in China — much more than is needed to upgrade pipes and water-treatment plants. Door-to-door recycling of filters could prove harder to manage than centralizing purification of household water in treatment plants. Also, filters in domestic purifiers could be a health risk if not changed frequently enough.

People's reluctance to switch from traditional ways or to use poor-quality water for tasks such as laundry could also undermine the success of the proposed plans.