Between 2015 and 2021, phosphate concentrations in rivers fell in 11 of the 16 European countries with sufficient data. In Spain they rose. This is one of the findings of a study by the Research Institute of Water and Environmental Engineering (IIAMA) of the Universitat Politècnica de València, led by researchers María Pachés Giner and Remedios Martínez and published in Environmental Science and Pollution Research.

The team has built an indicator of human pressure on rivers, HPRE (Human Pressure on River Ecosystems), from Eurostat data. It combines two parameters: biochemical oxygen demand, which reflects organic pollution, and phosphates, which indicate nutrient input and the risk of eutrophication. Beyond describing each country’s current state, it calculates how fast each one is improving and whether that pace is enough to reach sustainable levels by 2030.

Organic pollution fell in 14 of the 18 countries analysed, but only Slovenia is moving at the required pace. Spain and Bulgaria come out worst: in Spain the organic load has fallen but remains high, and phosphates increased. The team itself notes that HPRE is a diagnostic tool and that a full ecological assessment also needs biological and hydromorphological indicators.

According to the researchers, the improvement seen in many countries is driven, among other factors, by progress in sewerage and wastewater treatment and by limits on nutrient discharges. They call for tighter control of urban, industrial and agricultural discharges. On the urban side, phosphorus is removed in treatment plants through tertiary treatment (nitrogen and phosphorus removal), and the new Directive (EU) 2024/3019 concerning urban wastewater treatment requires it on this timetable:

  • Each Member State must publish its list of areas sensitive to eutrophication no later than 31 December 2027.
  • Treatment plants of 150,000 population equivalent or more that do not yet have tertiary treatment must add it in stages (30% by 2033 and 70% by 2036). And all of them, including those that already have it, must meet the Directive’s limits no later than 31 December 2039: 0.5 mg/l total phosphorus or a minimum 90% reduction, plus a nitrogen limit.
  • Agglomerations of 10,000 population equivalent or more discharging into sensitive areas must also comply in stages, from 20% by 2033 to all of them by 2045, a deadline Member States may extend by up to eight years in certain cases. For plants below 150,000 population equivalent, the phosphorus limit, where it applies, is 0.7 mg/l or an 87.5% reduction.

In Spain, where phosphates rose over the period studied, that timetable sets much of the work ahead for treatment plants over the next two decades. Wastewater treatment is one of North Line’s areas of work.

Sources: TecnoAqua, 29 September 2026. Original paper: “Evaluating river water quality in Europe: a novel methodology for tracking human impact and sustainable development goals alignment”, Environmental Science and Pollution Research, 2026, doi:10.1007/s11356-026-38063-6. Directive (EU) 2024/3019 of 27 November 2024, Article 7 and Annex I. Image: TecnoAqua.