Gnesta is planning a new intake at Lake Klämmingen, a waterworks, a raw-water pumping station and new pipes. The system is intended to combine surface water with the existing groundwater source as a reserve. The investment framework is SEK 447 million, but that is a maximum authorised amount rather than a final project cost.
What happened?
The municipality describes the scheme as one of its largest infrastructure investments. Surface water from Lake Klämmingen will form the basis of normal supply, while the present groundwater source can remain as a reserve. The plant is intended to use the sources together or separately and include reservoirs, backup power and several layers of technical protection.
Long-life elements such as buildings and process spaces will be sized for several decades. Pumps and other equipment will initially be installed for current needs with a margin. Capacity can therefore be added in stages without rebuilding the whole facility.
Location
Gnesta, Södermanlands län
Impact and significance
The need is not based solely on population growth. Groundwater availability varies with rainfall and recharge, and two dry years in succession can cause major problems. The present source also has elevated chloride levels, increasing corrosion risk in the pipe network and potentially contributing to leaks. The municipality therefore considers a new plant necessary even if population growth is slower than earlier forecasts.
Two independent sources provide more options during drought, contamination or technical disruption. When groundwater no longer carries the routine main supply, the aquifer can also recover and become a stronger reserve.
Background
During the 2025 water shortage, an emergency plant treated water from Lake Frösjön and infiltrated it through the ground to reinforce the aquifer. This was combined with lower network pressure, a watering ban, leak detection and reduced consumption. The emergency plant has only one treatment line, limited scope for expansion and no process for removing algal toxins. It is therefore an emergency reinforcement rather than the long-term main solution.
The planned plant will use raw water of more consistent quality and include treatment for algal toxins.
Latest update
The council's SEK 447 million investment framework covers permits, design work, the intake, waterworks, pumping station and pipes. It should not be read as money already spent or a guaranteed final price. The municipality refers readers to the project page for forthcoming schedules, decisions and answers to common questions.
Sources
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Reviewed: 2026-09-11. Independent editorial content. WUA Sverige is not affiliated with any political party.