Waternet expects drinking water demand in its supply area to rise from about 95 million m3 in 2024 to about 107 million m3 in 2035. Its two published capacity projects add about 11 million m3 a year, and the larger of them is not due in use until 2031.
Two projects, two timetables
The first is at the Amsterdam Water Supply Dunes. A permit granted in 2025 allows Waternet to raise production at Leiduin from 70 billion liters to 75 billion liters a year. No works start date or cost has been published.
The second is a new slow sand filter building at Weesperkarspel, adding up to 6 billion liters a year. Waternet's project page plans construction from 2027 and use from 2031. A November 2024 procurement notice put the works contract at an estimated €54 million, and a June 2026 notice sought €4 million of prefab concrete for twelve new filter beds.
Why the gap matters
Waternet says its current sources can produce enough drinking water until 2030, after which there may be too little without action. The forecast assumes population growth of about 165,000 people. On July 1, 2025, a hot day, more than 14 million liters of tap water had been used by 8 a.m.
Beyond 2035
The longer view is larger. Waternet's Weesperkarspel page forecasts 122 million m3 a year by 2050, 27 million m3 above today's 95 million m3. Its director has named water saving, alternative sources and other water qualities for business customers as options, but no project or volume has been set.
How the second phase of Waternet's split, its tariffs after the one-off 2026 cut and its post-split borrowing will affect this program are among the questions the report answers. The full report, Water Utility of the Future: Waternet, is available for USD 499. For a free overview, read the Waternet Utility Snapshot.