Agricultural Wastewater Reuse Necessitates Treatment Investment

With increased wastewater reuse occurring on farms, effective wastewater treatment is paramount, researchers say.

A new study published in Environmental Research Letters put a spotlight on farmers who use urban wastewater to irrigate their fields. The findings highlight the need for policymakers to balance the benefits of water reuse with “the need to invest in wastewater treatment to protect public health,” according to the journal article.

The study revealed that “crops covering almost 36 million hectares — an area roughly the size of Germany — are irrigated with water from rivers and lakes used by cities within 40 km (25 miles) upstream to discharge sewage,” Reuters reported.

The study assessed health risks linked to irrigation. Situating farms near cities enables farmers to access nutrient-rich wastewater to irrigate their crops, but it also has consequences.

“According to the study, some 65 percent of all irrigated land areas are within 40 km downstream of urban areas. A significant amount of that land is in countries with very limited wastewater treatment, exposing 885 million urban consumers, farmers and food vendors to health risks,” BBC News reported.

Pay Drechsel of the International Water Management Institute, an author of the study, noted that the research registered a 50 percent uptick in land irrigated with untreated wastewater compared to previous studies.

"The previous figure was not based on science, so this new approach combines geographic information, and is the first scientific approach to get hold of the area that is irrigated with raw or diluted wastewater," Dreschsel said, per BBC News.

Anne Thebo of the University of California, Berkeley, an author of the study, stressed the importance of investment in wastewater infrastructure.

"As long as investment in wastewater treatment lags far behind population growth, large numbers of consumers eating raw produce will face heightened threats to food safety," she said, per Reuters.