According to data from the National Consumer Water Information System (SINAC), water supply networks in the Sierra de Cádiz region exhibit the highest nitrate contamination indices in the province. Specifically, the networks of La Fábrica in Bornos and La Perdiz in Arcos show particularly elevated values.
In Bornos, the La Fábrica network, which supplies water to over 60% of the population, recorded 46 mg/l in 2024 analyses. Although a subsequent measurement in November 2025 indicated a slight reduction to 40 mg/l, this value remains significant. In contrast, other areas of Bornos, such as Coto de Bornos or Molino Ancho, reported much lower levels, at 18 and 16 mg/l respectively.
The current legal limit for nitrate presence in water is 50 mg/l, with results between 30 and 50 mg/l considered critical. However, various scientific studies suggest that this regulation may be insufficient to protect long-term health.
In Arcos, the La Perdiz network, serving about 200 inhabitants, showed 30 mg/l in 2024, a figure that rose to 32 mg/l in April 2025, which Ecologistas en Acción interprets as a potential “aggravation of the problem.” Other areas of Arcos also recorded high values in 2024, though below 19 mg/l, while Jédula stood out with 0 mg/l in 2026.
“"The origin of these elevated levels is, predictably, the contamination of groundwater by the intensive use of nitrogen fertilizers in agriculture, especially in irrigated areas."
Given this situation, Ama Natura–Ecologistas en Acción calls for reinforced controls on water supply and urges the Government to review Royal Decree 3/2023 on human consumption water, in order to reduce the maximum permitted nitrate limit. They argue that it is “inconsistent” for the drinking water threshold to double that allowed in river ecosystems, given the known health risks.
