Amsterdam's drinking water company needs about 15 to 19 million cubic metres a year of extra capacity between 2030 and 2050. Its named new sources add up to about 30 million, if every one is delivered in full.
Short of the 2030 need until 2031
Waternet's 2024 regional action plan puts regular production capacity at 95 million cubic metres a year, against a requirement of 107 million by 2030. Two measures due before 2030 add 5 million cubic metres a year from the Leiduin dunes and 5 million from a bulk supply from neighbouring utility PWN, 10 million in all against a stated need of 14 million. A new slow sand filter at Weesperkarspel, adding 6 million, is now expected in use in 2031.
The dunes were already near their limit
North Holland province raised the dune abstraction ceiling from 70 to 75 million cubic metres a year on 13 August 2025. A draft nature permit decision of April 2025 says demand growth and extra deliveries to PWN and Dunea had threatened to break the old ceiling. Waternet's operational reserve is 5%, with a target of 10% by 2050.
The sources after 2030 carry conditions
The options are a Weesperkarspel expansion of 8 million cubic metres a year in 2031 and 8 million more in 2040, about 6 million of brackish seepage from the Horstermeerpolder and about 8 million from the WAAG project from 2035. WAAG needs new river intakes, and Rijkswaterstaat has said it cannot guarantee enough water at any of them.
Demand is not falling fast enough
People in Waternet's area used 141 litres each a day in 2021, against a national target of 100 litres by 2035. The national saving plan says its goal will probably be missed with current measures.
How reliable Amsterdam's sources are, what drought and treatment residues mean for supply and which national decisions matter are set out in the report. The full report, Water Security and Supply Outlook in Amsterdam, is available for USD 249.