Tap water in the Netherlands: a network without chlorine

Tap water without disinfectant in the network must itself be low in nutrients. Smeets and colleagues describe the principle as starving rather than killing. The inspectorate calls it biological stability and, in its report for 2024, the most important success factor for chlorine-free supply. The price appears in the same table.

Aeromonas shows whether bacteria are multiplying in the pipe network. In 2024, 140 of 8,385 measurements were above the value, i.e. 1.67%. That is 52% of all non-compliances among the operational parameters, the highest single figure in the group. It is not assessed from a health perspective. The limit is 1,000 colony-forming units per 100 millilitres; Leiduin reported an average of 0, Scheveningen 1.

The Inspectie Leefomgeving en Transport (ILT), the Dutch supervisory authority for the environment and transport, inspects drinking water every year. Its report for 2024, dated 4 November 2025, lists 682,474 measurements and 1,081 deviations, i.e. 0.16%. This means that 99.84% of measurements met the standard.

Where the deviations occurred matters more than the rate. 88.71% concerned indicator parameters, i.e. substances with no direct effect on health. Escherichia coli was tested 61,442 times, with 20 non-compliances, and enterococci 13,782 times, with 15 non-compliances. For the chemical parameters, there were 37 cases out of 93,295 measurements. The limits are set out in the Drinkwaterbesluit; the framework law is the Drinkwaterwet. Both transpose the European Drinking Water Directive into national law. According to figures from the Vewin association, 10 suppliers delivered a combined 1.094 billion cubic metres in 2024.

On 21 December 2022, the Netherlands lowered the lead limit from 10 to 5 micrograms per litre. It applies at the point of delivery and at the tap. In Germany, under the Drinking Water Ordinance, 10 micrograms will continue to apply until 11 January 2028, and 5 thereafter. The Dutch rule therefore takes effect five years earlier.

In 2024, 1,679 lead measurements in the supply area were evaluated, and 28 were above 5 micrograms per litre. All 28 concerned the customers' domestic plumbing, or the repeat sample was unremarkable. About a third were in buildings dating from before 1960. Nickel and copper are included in the same programme and remained well below the limit. Cadzand reports 2.4 micrograms of nickel per litre against a limit of 20, the Weesperkarspel plant 1.5 micrograms of copper against 2,000. There are wide differences between the suppliers. Dunea reports 8.00%, PWN (the supplier for the whole of North Holland) 6.12%, Waternet 3.88% and Evides 0.67%. The sector as a whole stands at 1.67%. The inspectorate points out that, owing to changed sampling methods, 2024 cannot be compared with previous years.

The spread follows the building stock, not the water quality in the network. According to the inspectorate, lead pipes are found mainly in homes dating from before 1960. Where more samples come from old neighbourhoods, the rate rises. Dunea supplies The Hague and Leiden, two cities with old historic centres.

For legionella, 1,561 measurements in 2024 produced exactly 50 exceedances, i.e. 3.20%. That is the highest rate of all four parameter groups reported by the inspectorate. At the point of use, there were 49 exceedances. All 49 were attributable to the customers' domestic plumbing.

The fiftieth case came from the Vitens plant in Loosdrecht and could not be confirmed in the repeat sample. The limit is set out in Article 36 of the Drinkwaterbesluit and is 100 colony-forming units per litre. Among the 956 measurements in domestic plumbing systems, the rate is 5.13%.

The Dutch statistics show the same pattern as the Portuguese and Croatian ones. The network stays clean. Anomalies only show up beyond the water meter.

Amsterdam draws its raw water from the Lekkanaal near Nieuwegein and from the Bethunepolder near Maarssen. The canal water infiltrates for around 90 days in the dunes near Vogelenzang, while the polder water stands for 3 months on average in the Waterleidingplas near Loenderveen. Two plants treat it: Leiduin and Weesperkarspel.

In the first quarter of 2026, Waternet took 358 samples for Escherichia coli from both plants, all negative, plus 54 for enterococci. Lead was below 0.2 micrograms per litre, against a limit of 5. Hardness at Leiduin was 7.4 to 8.1 degrees of German hardness, with an average of 7.8.

The 7.8 degrees are the result of a decision. In 2015, Waternet reduced the hardness from 8.4 to 7.8 and stepped up softening at the plant. Since then, all customers have received the same water, whether in Amsterdam, Amstelveen, Diemen or Heemstede. Less limescale here also means less detergent.

4 figures show how widely hardness varies along the coast. Scheveningen measures 8.1 degrees of German hardness, Rotterdam 7.6, Kamperland and Domburg in Zeeland 8.9, Ouddorp 12.4. Dunea's scale classes everything below 8 as soft, up to 12 as medium and from 12 as fairly hard.

Dunea publishes quarterly values for Scheveningen, most recently for the second quarter of 2026. Chloride is at 60 milligrams per litre, sodium at 59.4, lead below 0.2 micrograms per litre. Escherichia coli, enterococci and Clostridium perfringens were each at zero.

Rotterdam gets its water from the Kralingen plant. In May 2026, Evides measured 9.5 milligrams of nitrate per litre there, against a limit of 50, and 1.9 micrograms of trihalomethanes. For Rotterdam, Evides lists 25 micrograms as the standard for trihalomethanes, the Drinkwaterbesluit value for water with disinfection. For Ouddorp, it lists 1 microgram, the signal value without disinfection. So the standard a supplier lists shows whether disinfection takes place at the plant.

Kamperland and Domburg get groundwater from the Huijbergen plant, Cadzand surface water from Braakman. The analyses for Amsterdam, The Hague and North Holland are carried out by a joint institute, Het Waterlaboratorium. Evides answers queries by postcode for the previous 12 months; the other three suppliers publish quarterly reports for each plant.

Texel, Zandvoort, Callantsoog and Den Helder are supplied by PWN. The supplier gives 7.9 degrees of German hardness for the whole of North Holland, as of December 2025. Behind the average, however, lies a range.

At the Bergen production site, hardness in the first quarter of 2026 fluctuated across 13 measurements between 8.0 and 12.9 degrees, with an average of 8.9. Chloride was between 74 and 113 milligrams per litre, against a limit of 150 as an annual average. Nitrate was 2.52 milligrams per litre; chlorate and chlorite remained below the limit of quantification. 90 samples for Escherichia coli were at zero.

However, PWN does not publish which plant supplies Texel. Anyone who needs the value for a specific address should ask the supplier.

Since 12 January 2026, a standard of 100 nanograms per litre has applied to the sum of 20 per- and polyfluoroalkyl substances (PFAS). The measured values are well below this: Amsterdam reports 11 to 18 nanograms, PWN's Bergen site 15 to 17, Rotterdam 12.

Alongside this, there is a stricter proposal. The Rijksinstituut voor Volksgezondheid en Milieu (RIVM), the Dutch National Institute for Public Health and the Environment, recommends 4.4 nanograms per litre in perfluorooctanoic acid equivalents. Perfluorooctanoic acid equivalents are a different metric from the sum of the 20 substances. Comparing the two figures directly is misleading. According to the RIVM, tap water from groundwater usually meets the guideline value of 4.4 nanograms, while tap water from surface water usually does not. Amsterdam, The Hague and Rotterdam use surface water.

Nevertheless, the RIVM continues to recommend drinking tap water. It says the amount of PFAS taken in through tap water alone is generally limited, so drinking tap water remains justifiable.

In 2024, Dutch suppliers issued 158 boil-water notices. 5 of them concerned supply areas with more than 10,000 connections. In the previous 5 years, large-scale boil-water notices had been issued twice in 2021 and once in 2023. The inspectorate describes the figure for 2024 as conspicuously high.

The 5 cases were spread across 3 suppliers: Waterleiding Maatschappij Limburg (WML) with one, Vitens with three, Brabant Water with one. All concerned groundwater plants. The suppliers suspect leaking treated-water reservoirs as the cause; Vitens also cites high groundwater levels after heavy rain. A boil-water notice means boiling for 3 minutes.

Travellers can draw a rule from this: at the start of your stay, check the supplier's service disruption notices. The companies publish them on their own websites.

Article 35 of the Drinkwaterbesluit lists who must carry out a Legionella risk analysis. The list includes buildings with a lodging function, i.e. hotels, as well as campsites, marinas and saunas. These are followed by bathing facilities with pools of 2 square metres or more and petrol stations with public showers. All are subject to supervision by the ILT.

One group is expressly exempt: recreatieverblijven, i.e. holiday homes and bungalows. A hotel room in Amsterdam therefore falls under the Legionella regime, while an individually rented holiday home on Texel does not. There, only the general duty of care applies. In Turkey, the same question mainly concerns hotel complexes.

The difference matters in practice, because bungalows are among the most common types of accommodation for trips to the Netherlands and often stand empty for days between two bookings.

If a home has stood empty for more than 7 days, Waternet gives a 3-step instruction. First, flush the toilet. Then open every hot and cold tap for at least 60 seconds, starting with the tap closest to the water meter. Finally, remember the outside tap.

A separate rule applies to the shower head. Hold it in a bucket of water that has already been flushed through and place a cloth over it before turning on the water. This keeps the spray mist in the bucket. The RIVM recommends flushing rarely used pipes once a week.

The instruction comes from the supplier, not from a filter manufacturer. It explains why bacteria grow in domestic plumbing in the first place.

In Amsterdam, tap water is also available free of charge on the street. Waternet keeps a list of its public water points as an open data file. On 1 August 2026, it contained 553 points, of which 445 were drinking water taps and 108 dog drinking bowls. Amsterdam accounts for 464 points, 387 of them for drinking.

The first public taps were built in 1903 as a substitute for missing household connections.