The Netherlands Court of Audit has investigated the concentration of 15 harmful industrial substances in Dutch surface waters that are a risk to human health and the environment. As an EU member state, the Netherlands has undertaken to reduce the presence of these substances by 2027. The 15 substances investigated are among the most harmful of the 122 harmful substances named in the Water Framework Directive (WFD) that must be brought below the agreed standard by 2027. The investigation found that no progress had been made on most of the 15 substances in recent years.
Court of Audit investigates concentrations of harmful substances
Government reports on chemical water quality in the Netherlands give only limited insight into whether our water is actually becoming cleaner. They state whether European standards have been breached, but the standards change over time. That is why the Court of Audit not only looked at pollution breaches but also examined the surface water concentration of 15 of the 122 harmful substances named in the WFD. They include carcinogenic PAHs (polycyclic aromatic hydrocarbons), PFOS, heavy metals such as lead and mercury, and dioxins. Surface water pollution has several causes; besides industrial discharges, there is pollution from precipitation and pollution from water that flows into the country from abroad.
No decline in concentration of most harmful substances
Our investigation relied on data on the concentration of the 15 harmful substances at all 61 monitoring stations in Dutch national waters. The figure on the left below shows the number of monitoring stations where each of the substances did and did not comply with the standard in 2023/2024. |
Under the WFD, if one substance breaches the standard, the chemical quality of the surface water in question is inadequate. To meet EU standards, all the bars in the left-hand table should be completely green by 2027. It is unlikely that they will be.
The figure on the right shows the surface water concentration of the 15 harmful substances in the period 2012-2024, i.e. regardless of changing standards. It shows that the concentration of 1 substance has developed favourably in most places, the concentration of 3 substances has worsened and 9 substances have neither increased not decreased. For 2 substances, most places monitored too little to draw conclusions.
12 of the 15 substances do not yet comply with the standard everywhere. No progress at most monitoring stations
Number of monitoring stations with/without breaches in 2023 or 2024
Development at monitoring stations, 2012-2024
| Substance | Improvement | Insufficient monitoring | No improvement | Deterioration |
|---|---|---|---|---|
| benzo[a]pyrene | 8 | 12 | 31 | 10 |
| benzo[b]fluoranthene | 10 | 12 | 27 | 12 |
| benzo[ghi]perylene | 20 | 12 | 25 | 4 |
| benzo[k]fluoranthene | 18 | 13 | 27 | 3 |
| fluoranthene | 10 | 12 | 34 | 5 |
| mercury | 3 | 16 | 32 | 10 |
| lead | 17 | 18 | 22 | 4 |
| nickel | 11 | 18 | 32 | 0 |
| cadmium | 35 | 20 | 6 | 0 |
| PFOS | 12 | 26 | 21 | 2 |
| tributyltin (cation) | 15 | 13 | 32 | 1 |
| hexachlorobutadiene | 10 | 16 | 7 | 28 |
| trichlorobenzene | 0 | 22 | 2 | 37 |
| PBDE | 2 | 19 | 11 | 29 |
| dioxins | 0 | 61 | 0 | 0 |
Breaches at almost every national monitoring station
The Court of Audit measured the concentration of 15 substances at each of the 61 national monitoring stations in 2012-2024 in order to map out how many substances breached the WFD. Almost all monitoring stations had recorded at least one pollution breach. Here, too, EU undertakings require all monitoring stations to be green by 2027.
At least 1 pollution breach at nearly all monitoring stations and usually no progress
The number of pollution breaches per monitoring station is shown on the left. The number of industrial substances with declining concentrations in 2012-2024 is shown on the right.
The Court of Audit has developed an interactive map showing which harmful substances breach the standard at each monitoring station.
Social and economic damage, risk to drinking water
Natuur & Milieu estimated in 2025 that industrial pollution cost the Netherlands at least €7 billion a year. The Court’s Board member Barbara Joziasse said, “Our investigation found little progress in tackling harmful industrial substances in surface water. Surface water pollution can have consequences for human, animal and plant health and puts pressure on drinking water supplies. The cost of water treatment can run into billions and is increasing. Water withdrawal from the Meuse has had to be stopped several times in recent years because of the poor quality. In addition, if we do not meet the European standards we committed to in 2000 by 2027, there is a risk of fines from the European Commission or cuts in European funding.”
Limited insight into permits and discharges
The Minister of Infrastructure and Water Management is responsible for issuing permits for industrial discharges into national waters. Compliance with permit conditions is monitored by Rijkswaterstaat (RWS). Our investigation found, however, that the minister has little insight into what is being discharged by which companies. RWS does not have a central data system with an up-to-date record of the companies, permits, and permitted and actual discharges. As a result, it is not possible to paint a national picture of which companies discharge into national waters and whether the discharges are permitted.