Norrtälje customers normally supplied with Lake Mälaren water may receive groundwater during tests of two reserve plants on 22–24 September. The utility says quality is good, but the water is harder and may require more detergent and leave limescale. Changes arrive with a delay of several days.
What happened?
Norrvatten is testing plant operation and delivery capacity during Preparedness Week. Groundwater replaces all or part of supply from Görvälnverket for customers on the relevant system. Network travel means changes may not align exactly with test days, and not every municipal household uses Norrvatten.
Location
Norrtälje, Stockholms län
Impact and significance
Hardness affects dosing and limescale rather than making water unfit. Households may adjust detergent according to instructions and see deposits on porcelain, sinks or kettles. Some businesses and aquarium owners may need composition details from the utility's Q&A or customer service.
Background
The reserve plants are intended for loss of supply from Görvälnverket. Controlled testing checks plants, pipes and capacity before a crisis. Returning to normal may release rust and discolour water; the utility describes this as harmless and advises flushing cold taps until clear.
Latest update
The plants supply water on 22, 23 and 24 September, with customer effects potentially later. Live notices from the utilities take priority. Unexpected odour, persistent discoloration or other deviations should be reported. The test notice does not generally require residents to change normal water use.
Sources
Related analysis
Reviewed: 2026-09-20. Independent editorial content. WUA Sverige is not affiliated with any political party.