Your Shower Water: What's in It and Why It Affects Your Skin and Hair

Summary

The water that flows from your showerhead is not the same as the water you drink. Your drinking water is regulated, tested, and safe. But your shower water has a different story — it's heated, aerated, and transformed into a chemical cocktail of chlorine, chloramine, heavy metals, and in some areas, contaminants like PFAS. This article reviews what research says is in Swedish shower water and what it actually means for your daily health.

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Why Your Shower Water Is Not the Same as Tap Water

When water is heated and sprayed through a showerhead, several things happen that change its composition:

1. Temperature: At 38-42 degrees C, chlorine reacts faster with organic material and forms trihalomethanes (THMs) — a group of carcinogenic compounds that evaporate with steam and are inhaled directly into your lungs.

2. Aeration: The shower atomizes water into millions of tiny droplets, dramatically increasing the water surface area and thereby the volatilization of airborne chemicals.

3. Contact time: In a 10-minute shower, your skin and lungs are continuously exposed to chemicals in a form (steam and atomized water) that makes them more bioavailable than regular skin contact.

4. Materials: Hot water from the water heater can contain higher levels of metals like copper and nickel, especially if the pipe system is old.

Research from Environmental Health Perspectives showed that a 10-minute shower can contribute as much THM exposure as drinking 2 liters of chlorinated water per day. And it's a daily exposure.

What's in Swedish Shower Water?

Chlorine and Chloramine

Swedish municipalities use chlorine or chloramine as a secondary disinfectant to prevent bacterial growth in the pipe network. The levels are low (typically less than 0.05 mg/L at the tap) but when the water is heated:

• Chlorine reacts with organic material and forms THMs
• Chloramine is more stable and won't dissipate by running the tap
• Both are oxidizing agents that damage the skin's natural barrier

Heavy Metals

In older properties with copper or brass pipes, hot water can corrode the metal and leach copper, lead, and nickel into the water. In Stockholm and other older city districts, there are still properties with lead and copper pipes from the 1950s and 1960s.

What research says about heavy metal exposure through showering:

• Nickel is a common contact allergen
• Lead can be present in water after prolonged contact with lead-soldered pipes

PFAS: Forever Chemicals

PFAS are a group of synthetic chemicals that are extremely stable and don't break down in the environment or in the body.

PFAS have been discovered in groundwater and surface water near certain Swedish military facilities and industries. Several Swedish water supplies have identified PFAS contamination and are working with advanced water treatment techniques to remove it.

Important: PFAS in drinking water is primarily an issue for specific areas with known contamination. Most Swedish households don't need to worry about PFAS in their regular drinking water.

When PFAS-contaminated water is heated, these compounds can become concentrated in the steam and be inhaled. Your skin's absorption capacity is up to 64% higher at 40 degrees C compared to room temperature. This is why your lungs and skin are exposed to much higher doses of chemicals in the shower than during other contact with chlorinated water.

How Does Shower Water Affect Your Skin?

Your skin's outer layer — the stratum corneum — acts as a barrier that retains moisture, protects against external substances, and maintains a healthy microbiome.

The Effect of Chlorine on Skin

Chlorine penetrates this barrier and oxidizes the lipids that hold skin cells together. This causes the skin to lose its natural moisture and become dry, rough, and irritated. Over time, this can lead to chronic barrier damage and an increased risk of eczema.

It oxidizes melanin in hair, which can lead to discoloration and weakening of hair follicles. A study in the Journal of Investigative Dermatology showed that regular bathing in chlorinated water can significantly alter the skin's microbiome. Order a water analysis test to find out exactly what's in your drinking water.

Heavy Metal Exposure Through Showering

Heavy metals like copper can leave a greenish coating on hair and cause brittleness. The oxidative damage from chlorine can accelerate skin aging and worsen eczema and psoriasis.

PFAS and the Skin's Absorption Capacity

PFAS can be absorbed through the skin, especially at high temperatures. When PFAS-contaminated water is heated, these compounds can become concentrated in the steam and be inhaled.

Who Is Most Affected?

People with atopic dermatitis, eczema, or sensitive skin are at the highest risk for negative effects from shower water. Children and the elderly are also particularly vulnerable because their skin is thinner and more permeable. Regular showers in chlorinated water can lead to elevated levels of chlorine in the blood — even without visible symptoms.

The Solution: Shower Filters

What does a shower filter do?

A shower filter with calcium sulfite and activated carbon neutralizes chlorine and chloramine before they reach your skin. Nordisk Renhet's shower filters use a combination of calcium sulfite (CaSO3) and granular activated carbon (GAC) for optimal filtration. The filter replaces the harmful chemical reaction with a harmless salt precipitation.

Shower filters remove up to 99% of free chlorine and significantly reduce chloramine. Research shows that people who switch to filtered shower water experience softer skin and less itching within two weeks. A study showed that people with atopic dermatitis experienced 40% less itching after four weeks of using a shower filter.

How the filtration technology works

Shower filters with activated carbon are particularly effective against chlorine and chloramine. Do shower filters work against heavy metals? Standard filters are not designed for heavy metals — for that, you need a filter with KDF-55D media. Nordisk Renhet offers a shower filter with both calcium sulfite and KDF-55D for broader protection. Filters with activated carbon can also absorb certain PFAS compounds, but this depends on filter design and PFAS type.

Filter replacement is recommended every three to six months, depending on water hardness and usage.

Shower Water in Swedish Cities

Stockholm has one of Europe's most advanced water treatment systems with good water quality. Gothenburg and Malmö have somewhat higher levels of chlorine and chloramine due to older pipe networks. Uppsala and Linköping are in areas with very hard water, which requires regular filter maintenance. In older buildings with lead pipes, hot water may contain elevated levels of lead.

Water hardness varies greatly across Sweden — from very soft in Norrland to very hard in Skåne. Hard water can contain high levels of calcium and magnesium, which can negatively affect skin and hair.

Frequently Asked Questions

How often should I change the filter?
Every three to six months, depending on water hardness and usage.

Does hard water affect skin and hair?
Yes, hard water can leave calcium and magnesium deposits on skin and hair, which can lead to dry skin and dull hair.

Do shower filters work against chlorine?
Yes, calcium sulfite-based filters can neutralize up to 99% of free chlorine.

What are THMs?
Trihalomethanes (THMs) are carcinogenic compounds formed when chlorine reacts with organic material in water. They evaporate with steam and are inhaled in the shower.

Is there Swedish research on shower water?
Yes, the Swedish Food Agency and Swedish universities have published several studies on chlorinated by-products in drinking water.

Your shower water deserves the same attention as your drinking water. It's the water you shower in every day.