​​​HSY has one working ground water intake plant: Kuninkaanlähde in Tuusula.

The Kuninkaanlähde water intake plant is located in Tuusula, in the Huhtariihi area. Its distribution area mainly includes the city districts of Korso, Vallinoja and Vierumäki in Vantaa.

An average of 2,000 m3 of ground water is pumped from Kuninkaanlähde every day. The pH of ground water is adjusted to level 8.0 with lye. Before being pumped into the network, the water is disinfected with UV light and a small amount of chlorine is added to it in order to maintain its microbiological quality in the water supply network.​