Nedre Romerike waterworks (NRV) supplies the areas northeast of Oslo with water. The main town supplied is Lillestrøm. In this area the main raw water source is surface water and the river Glomma. Glomma, Norways longest river, is a recipient for wastewater from upstream towns so the water needs sophisticated treatment (see also wastewater treatment). Water purification in the NRV is achieved through a multi-phased process by flocculation with a SuperPulsator (combining flocculation and clarification functions) and a two-media filter (filtralite), a carbon filter, chlorination, as well as UV-filtration (see also UV tubes).
The waterworks are located in rock caverns north of Lillestrøm. The PPT by Lena Solli Sal gives an overview of the water treatment at NRV.