Calculator
Estimate what your site pays in Dutch wastewater levy (zuiveringsheffing or verontreinigingsheffing) under the 2026 rules, compare it across water boards, and see what reducing your load would save. The form starts with the figures from the worked example further down this page, so replace them with your own. If you do not measure heavy metals, leave those fields empty.
Other substances (optional)
What if you cut your load?
How the zuiveringsheffing is calculated
Dutch companies pay zuiveringsheffing when they discharge wastewater to the municipal sewer, and verontreinigingsheffing when they discharge directly to surface water. Both are charged per pollution unit (vervuilingseenheid). One pollution unit for oxygen demand equals 54.8 kg of oxygen per year.
Your oxygen demand is calculated from your annual volume and the concentrations of organic carbon and nitrogen in your wastewater. Some other substances are counted separately. Under the water boards’ 2026 rules (as in Waterschap Rivierenland’s 2026 ordinance), 1 kg of chromium, copper, lead, nickel, silver or zinc is one pollution unit, as is 100 g of arsenic, cadmium or mercury and 20 kg of phosphorus. A tax-free allowance linked to your oxygen-demand units is deducted first, and for sites below 1,000 oxygen-demand units these substances are normally set to nil unless the water board shows otherwise. Boards decide which substances they levy, so check your board’s current belastingverordening.
The tariff depends on where you discharge. For the sewer and regional waters, each water board sets its own tariff, which is the same for both levies. For discharges to state waters (rijkswateren), the national tariff applies: EUR 37.28 per unit.
What changed in the zuiveringsheffing on 1 January 2026
The amended Waterschapswet and Waterwet replaced the analysis parameters used to measure your load:
- COD is replaced by TOC. TOC is converted to oxygen demand with a fixed factor: COD = 3 × TOC. The change removes hazardous reagents from laboratory analysis.
- Kjeldahl nitrogen is replaced by total nitrogen, with nitrite and nitrate deducted.
- Table companies (sites below 1,000 pollution units, assessed on their water intake) also use the factor of 3.
A factor of 3 matches the average COD to TOC ratio of household wastewater, which research found to be similar to the average for business wastewater. Individual sites can therefore move either way, depending on how their real ratio compares with 3.
Worked example
The figures below are hypothetical. A food processing site discharges 50,000 m³ a year to the sewer, with TOC of 650 mg/l, total nitrogen of 90 mg/l and nitrite plus nitrate of 10 mg/l.
- Oxygen demand: 50,000 × (3 × 650 + 4.57 × 80) / 1,000 = about 115,800 kg a year
- Pollution units: 115,800 / 54.8 = about 2,113
| Where the site is located | 2026 tariff per unit | Annual levy |
|---|---|---|
| Aa en Maas (cheapest water board) | EUR 66.72 | about EUR 141,000 |
| National average | EUR 86.77 | about EUR 183,300 |
| Delfland (most expensive water board) | EUR 115.33 | about EUR 243,700 |
| Direct discharge to state waters (Rijk tariff) | EUR 37.28 | about EUR 78,800 |
The same discharge costs about EUR 100,000 a year more in Delfland than in Aa en Maas. At the average tariff, cutting the organic and nitrogen load by 30% saves about EUR 55,000 a year, every year.
The TOC factor: a saving many sites have not checked
The standard factor of 3 is an average. If your wastewater’s measured COD to TOC ratio is below 2.5, you can apply for a correction, at your own cost and backed by measurement; if it is above 3.5, the authority can apply one. The correction is partial: under the 2026 ordinances, the applied factor becomes your measured ratio divided by 2.5 (or by 3.5) and multiplied by 3. A ratio between 2.5 and 3.5 changes nothing. Rijkswaterstaat advises taking 20 to 100 comparative samples over 24 months, depending on the type of wastewater.
In the worked example, a measured ratio of 2.0 gives an applied factor of 2.4 ((2.0 / 2.5) × 3). That lowers the levy at the average tariff from about EUR 183,300 to about EUR 152,500, a saving of roughly EUR 30,900 a year without changing the process. A measured ratio of 2.4 gives a factor of only 2.88 and saves about EUR 6,200. If you have historical COD and TOC data, compare them before commissioning a sampling campaign.
2026 tariffs for all 21 water boards
| Water board | 2026 tariff per pollution unit |
|---|---|
| Aa en Maas | EUR 66.72 |
| Amstel, Gooi en Vecht | EUR 92.79 |
| Brabantse Delta | EUR 83.55 |
| De Dommel | EUR 78.48 |
| De Stichtse Rijnlanden | EUR 78.48 |
| Delfland | EUR 115.33 |
| Drents Overijsselse Delta | EUR 84.69 |
| Hollands Noorderkwartier | EUR 89.00 |
| Hollandse Delta | EUR 94.21 |
| Hunze en Aa's | EUR 85.37 |
| Limburg | EUR 102.23 |
| Noorderzijlvest | EUR 106.27 |
| Rijn en IJssel | EUR 73.34 |
| Rijnland | EUR 95.87 |
| Rivierenland | EUR 76.28 |
| Scheldestromen | EUR 91.12 |
| Schieland en de Krimpenerwaard | EUR 79.34 |
| Vallei en Veluwe | EUR 86.00 |
| Vechtstromen | EUR 81.08 |
| Wetterskip Fryslân | EUR 77.44 |
| Zuiderzeeland | EUR 84.50 |
| Average of all 21 water boards | EUR 86.77 |
| Rijk, discharges to state waters | EUR 37.28 |
Each water board charges the same tariff for zuiveringsheffing and verontreinigingsheffing. The figures come from Statistics Netherlands (CBS), which compiles them from the water boards’ 2026 budgets, and match the tariffs the boards publish themselves. If your assessment shows a different tariff, choose “Enter a tariff” in the calculator and use the figure on your assessment.
Ways to reduce your levy
- Check your factor. Compare COD and TOC data to see whether a lower conversion factor is worth pursuing.
- Segregate streams. Keep clean cooling water, rainwater and rinses out of the process stream, so they are not mixed into a concentrated discharge.
- Reduce the load at source. Product losses, cleaning practices and changeovers often account for a large share of organic load.
- Pretreat on site. Biological or physico-chemical pretreatment can remove most of the organic load before discharge. Our guide to industrial wastewater treatment plant cost shows how to weigh the investment against the levy.
- Reuse water. Reuse lowers your intake and discharge volume, although a reuse system produces a concentrate that still needs a route.
Want to know what your site could save?
We review your levy assessment, your COD and TOC data and your reduction options, independently of any equipment supplier.
Frequently asked questions
What is the difference between zuiveringsheffing and verontreinigingsheffing?
Zuiveringsheffing applies to discharges to the municipal sewer, which the water board treats. Verontreinigingsheffing applies to direct discharges to surface water. Water boards charge the same tariff for both; discharges to state waters pay the national tariff.
How much is one pollution unit in 2026?
It depends on your water board. In 2026 tariffs range from EUR 66.72 (Aa en Maas) to EUR 115.33 (Delfland), with an average of EUR 86.77. Discharges to state waters pay EUR 37.28.
Does salt in our wastewater count towards the levy?
It depends on your water board. The rules allow a board to levy chloride and sulphate at 650 kg per pollution unit, but ordinances such as Waterschap Rivierenland’s 2026 ordinance exclude them. Check your board’s ordinance, and remember that salts still matter for your discharge permit.
We are a table company. Does this calculator apply?
Table companies, below 1,000 pollution units, are usually assessed on water intake multiplied by a coefficient rather than on measurement. The calculator flags results below 1,000 units so you can check which method your water board uses.
Is the calculator result what we will pay?
No. It is an estimate using the 2026 method and published tariffs. Your assessment depends on your water board’s measurement, sampling and any corrections it applies.
Sources
- Informatiepunt Leefomgeving: Belangrijkste elementen verontreinigingsheffing and Wijziging van de Waterschapswet en de Waterwet
- Staatsblad 2026, 142: Besluit omrekenfactor TOC
- Waterschap Rivierenland: Verordening zuiveringsheffing 2026
- Statistics Netherlands (CBS): Waterschappen; tarieven heffingen, 2026, cross-checked against the 2026 tariff pages of Delfland, Rijnland, Vechtstromen, De Stichtse Rijnlanden, De Dommel and Aa en Maas, Brabantse Delta and Rivierenland
- VEMW: Waterprijzen voor zakelijk gebruikers blijven stijgen, January 2026
Written by the Brine Consulting advisory team. The Brine Consulting advisory practice includes Osis G. Kalache, P.Eng., a senior wastewater process engineer with more than 17 years in industrial wastewater treatment and process optimization, and Cesar J.M. Chu Ortega, a water-tech strategist with expertise in water reuse, zero liquid discharge and industrial wastewater treatment. Meet our experts.
Brine Consulting estimate. Results are not a tax assessment and do not replace the assessment by your water board or Rijkswaterstaat.