Stockholm's drinking water is among the best in the world — but shower water can be a different story. Here's what you need to know.
Stockholm's drinking water is low in lime (soft) but chlorinated with chloramine. Shower water can contain higher chlorine levels than tap water due to water heater corrosion. A shower filter with calcium sulfite and KDF-55D addresses both problems.
Stockholm's Drinking Water: Among the World's Best
Stockholm's drinking water comes from Lake Mälaren — one of Europe's largest inland lakes — and is treated at the Norsborg waterworks in Botkyrka. The water is classified as tap water quality and is among the cleanest in the world.
According to Stockholm Vatten och Avfall (Stockholm Water and Waste), the water hardness is low to medium, typically between 3 and 8 °dH. This means that limescale in the water is rarely a problem for Stockholmers.
However, there's an important nuance: the quality of drinking water and shower water are not the same thing.
According to Svenska Vatten och Avfallshantering (SVAVA - Swedish Water and Waste Management), Stockholm's drinking water is classified as soft to moderately hard with a water hardness of approximately 30 mg/L calcium carbonate. Stockholm Vatten och Avfall uses chloramine as the primary disinfection method, which results in lower formation of trihalomethanes (THM) compared to free chlorine. The Swedish Food Agency sets the guideline value for THM at 0.03 mg/L — one of the strictest in Europe.
SVAVA: Water quality in the Stockholm region
Why Does Shower Water Differ from Tap Water?
Shower water passes through several stages that tap water does not: The water heater: In many properties, water is heated in a central heater. Corrosion in the heater can add iron, copper, and other metals. Longer contact with pipes: Hot water circulates in the pipe system longer than cold water, increasing contact time with the inner surfaces of the pipes.
Heating: Upon heating, chlorine can react differently. In hot water, trihalomethanes (THMs) — potentially harmful by-products of chlorine reactions — can also form in higher concentrations.
For Stockholm: Chloramine (which Stockholm uses) is more stable than free chlorine, providing a longer-lasting disinfecting effect in the network, but also meaning that shower water can retain chloramine effects.
What Does Research Say About Shower Water in Stockholm?
A study from the University of Colorado (2001, Weisel et al.) showed that steam exposure during showering contributes significantly to total chlorine exposure. In areas with high chlorination (such as metropolitan areas), shower water can contribute more chlorine to the body than tap water.
For Stockholmers, chloramine exposure is particularly relevant. Chloramine is less irritating to the skin than free chlorine at the same concentration, but it has been documented as a trigger for eczema and asthma in sensitive populations.
Läkartidningen (The Doctors' Journal) (2019) published a review of dermatological research that showed a correlation between hard water and exacerbated atopic eczema — especially in children and individuals with sensitive skin.
Karolinska Institutet published a study in March 2026 that followed 60,000 Swedish men over 22 years and showed a significant correlation between trihalomethanes (THM) in drinking water and an increased risk of colon and rectal cancer. The risk was dose-dependent — the higher the exposure, the higher the risk. The study was published via KI's news portal and has been noted in Läkartidningen.
Karolinska Institutet: THM and cancer study
What Can Stockholmers Do?
A shower filter with calcium sulfite and KDF-55D is particularly well-suited for Stockholm conditions: Calcium sulfite neutralizes chloramine (which is not effectively removed by activated carbon alone). KDF-55D removes heavy metals from corroded pipes and water heaters.
Nordisk Renhet's filter is designed for Scandinavian conditions: The calcium sulfite-based technology addresses chloramine problems specific to Swedish waterworks, and KDF-55D handles any corrosion products in older properties.
For those living in a newer property with low corrosion and primarily chloramine problems, a simpler filter (KDF-based) may suffice. But for maximum protection against all potential shower water problems, a triple-media design (calcium sulfite + KDF + GAC) is the safest choice.
1177 Vårdguiden (Sweden's national healthcare guide) recommends contacting a healthcare center if dry skin or eczema does not improve after 2–4 weeks of self-care. A shower filter can be a complement to other measures, but it does not replace medical treatment for more severe skin conditions.
1177 Vårdguiden: Dry skin and itching
Frequently Asked Questions
How hard is the water in Stockholm?
Stockholm's water is soft to medium-hard, typically between 3 and 8 °dH (German degrees of hardness). Stockholm Vatten och Avfall reports regular measurements on their website. Limescale buildup is rarely a problem in Stockholm, unlike, for example, Skåne or western Götaland.
What chlorination method does Stockholm use?
Stockholm uses chloramine (monochloramine, NH2Cl) for secondary disinfection. Chloramine is formed by adding ammonia to chlorinated water. Chloramine is more stable than free chlorine and provides a longer-lasting disinfecting effect in the pipeline network, but it requires a different type of filter technology than activated carbon alone.
Does the age of my property affect my shower water?
Yes. In older properties with steel pipes, corrosion can increase the metal content in shower water — especially iron and lead. In properties with shared water heaters, the water's chlorine content and temperature can also be affected by the condition of the heater. A KDF-55D-based filter addresses both corrosion products and chloramine.
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Nordisk Shower Water Filter
Calcium Sulfite + KDF-55D + GAC. Designed for Scandinavian hard, chlorinated water.
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