For many years, farmers in England and Wales have been using the sediment from wastewater treatment plants to enrich their fields and grasslands. The material is cheaper than artificial fertilizers and pesticides, making it an attractive alternative in times of rising costs. Millions of tonnes are spread over the countryside annually.
Significant amounts of chemical substances have been found in these residues, including heavy metals, microplastics, and so-called PFAS, known for their persistence. These substances do not naturally disappear from the environment but instead accumulate in the soil and can enter the food chain via crops.
A major problem is that the pollution is not limited to agricultural land. Through rain and leaching, the substances also reach surface water. Studies show that rivers and streams are increasingly burdened with these residues, further worsening existing water pollution.
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Doctors and environmental organizations warn that the consequences for public health can be serious. They point to links between long-term exposure to PFAS and health problems, including certain types of cancer. They also emphasize that current policy amounts to a large-scale experiment where the risks have not been sufficiently mapped.
British farmers defend their choice by pointing to the economic reality. For many agricultural businesses, cheap sewage sludge is the only affordable way to keep their land productive. They emphasize that its use is officially permitted and that they operate within existing regulations. At the same time, some farmers acknowledge that they depend on a system whose consequences will only become clear in the longer term.
The British government has now responded to the growing criticism. Plans have been announced to tighten the rules for using sewage sludge. This includes stricter controls on composition, more intensive monitoring of effects, and possibly banning certain harmful substances.