Shower filters and hard water: do they help hair and skin?
Do shower filters work? What hard water and chlorine do to hair and skin, what filters can and cannot remove, and simpler fixes like chelating shampoo.
Written by the Glowpedia team · not yet reviewed by our dermatologist
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Shower filters went viral with videos of brown, dirty-looking cartridges and suddenly shiny hair. Part of the problem is real. But much of the fix is simpler than a filter, and most filters do not do what people think they do.
Quick answer: Hard water contains calcium and magnesium that can leave a film on hair, making it feel dull, stiff and hard to lather. Chlorine can make hair and skin feel drier. Most shower filters reduce chlorine but remove little or no hardness. A chelating or clarifying shampoo used now and then is a simple fix for mineral buildup. Only a whole-house water softener truly softens water.
What is hard water?
Water becomes "hard" when it flows through soil and rock and picks up minerals, mainly calcium and magnesium. How hard your water is depends on where you live and where your water comes from.
Signs that your water is hard:
- White, chalky crust (scale) on taps, shower heads and kettles.
- Soap and shampoo that do not lather well.
- A filmy feeling on your hands after washing.
- Spots on glasses and dishes.
Hard water is not a health risk to drink. It is mostly a nuisance for pipes, appliances and, for some people, hair.
What does hard water do to hair?
Minerals in hard water can react with shampoo, sweat and hair products to form a film on the hair surface. Over time, this buildup may:
- Make hair feel coated, rough, stiff or "straw-like."
- Reduce shine and lather.
- Make color-treated hair look dull or brassy. Water with iron or copper can add orange or greenish tints, especially to light hair.
- Make curls look limp or frizzier.
What about breakage? The evidence is mixed. A small lab study found that soaking hair in hard water did not reduce its strength or elasticity compared with distilled water. Other lab work found that hardness minerals taken up into the hair fiber can make it stiffer. So hard water probably affects how hair feels and looks more than whether it breaks.
If your hair is already dry and damaged or bleached, mineral buildup may be more noticeable.
What does hard water do to skin?
The same mineral film can leave skin feeling tight and dry after a shower, especially if you use a soap-based cleanser. Hard water also makes it harder to rinse soap off completely.
People often ask whether hard water causes eczema. A large UK trial installed water softeners in the homes of children with moderate to severe eczema. It found no overall improvement in eczema severity compared with usual care alone. Researchers are still studying whether softened water might help prevent eczema in babies, but there is no clear answer yet. If you have eczema-prone skin, gentle cleansers and moisturizer matter far more than your water.
What does chlorine do?
Many cities add small amounts of chlorine or chloramine to tap water to kill germs and keep it safe to drink. This is an important public health measure.
At tap-water levels, chlorine can make hair and skin feel a little drier and may slightly fade hair color over time. The effect is much stronger for regular swimmers, because pool water contains far more chlorine.
What can shower filters actually do?
| Filter type | What it mainly reduces | What it does not remove |
|---|---|---|
| Vitamin C cartridge | Chlorine and chloramine | Calcium and magnesium |
| Copper-zinc media (often called KDF) | Chlorine, some metals | Most hardness |
| Activated carbon | Chlorine (works less well with hot, fast-flowing water) | Hardness |
| Whole-house ion-exchange softener | Calcium and magnesium (true softening) | Not a shower filter; installed on the main water line |
Vitamin C (ascorbic acid) is a well-known way to neutralize chlorine and chloramine in water. But a small shower cartridge has only seconds of contact with hot, fast-moving water, and independent testing of shower filters is limited.
A few things to keep in mind:
- "Softening" claims need proof. If a shower filter says it softens water, look for lab results showing less calcium and magnesium, not just chlorine.
- Brown cartridges are not proof. Discoloration can come from rust in old pipes, the filter material itself or harmless sediment.
- Cartridges need replacing. An old cartridge may stop working, and some can grow bacteria if left too long.
Simpler fixes that work
Use a chelating shampoo
A chelating shampoo contains chelators, ingredients that grab onto metal minerals so they rinse away. Look for ingredients such as disodium EDTA, tetrasodium EDTA, phytic acid or sodium citrate, or labels like "hard water" or "chelating."
Use it once a week or every two weeks, depending on how your hair feels. One wash often makes a noticeable difference.
How to use it, step by step:
- Wet your hair thoroughly with warm water.
- Massage a small amount of chelating shampoo into the scalp and work it through the lengths.
- Leave it on for a minute or two, or as the label suggests, so it has time to bind the minerals.
- Rinse well. If your hair still feels coated, repeat once.
- Follow with conditioner or a mask on the mid-lengths and ends, leave it on for a few minutes, then rinse.
- Use a leave-in conditioner or a few drops of hair oil on the ends if your hair tends to be dry.
Go back to your usual gentle shampoo for the rest of the week.
Clarify now and then
A clarifying shampoo is a stronger cleanser that removes buildup from styling products, oils and dry shampoo. Some also contain chelators. Once or twice a month is plenty for most people.
Condition afterward
Chelating and clarifying shampoos can leave hair feeling dry. Always follow with a rich conditioner or mask. A leave-in conditioner helps keep the hair surface smooth.
Look after color-treated hair
If your hair is dyed or bleached, wait several days after coloring before using a chelating shampoo, as it can fade fresh color. A purple or silver shampoo can help tone down brassiness in blonde and grey hair. See color-treated hair.
Look after your skin
- Take shorter showers in warm, not hot, water.
- Use a gentle, soap-free body wash.
- Apply moisturizer while skin is still slightly damp.
Should you buy a shower filter?
It depends on what you want:
- If you mainly notice a chlorine smell or your hair or skin feels drier since moving, a vitamin C or carbon filter is a reasonable thing to try. Do not expect it to soften water.
- If your problem is mineral buildup (dull, coated, stiff hair), a chelating shampoo is usually simpler and more effective.
- If you have very hard water and want softer water for the whole home, a whole-house softener is the only real solution. Talk to a plumber about whether it suits your home.
What not to mix
- Chelating shampoo right after coloring. It can lift fresh color. Wait a few days.
- Chelating every wash. This can dry hair out. Once a week or less is enough for most people.
- Strong vinegar or lemon rinses. They can sting the scalp and dry the hair if used too often or undiluted.
How long until results?
A chelating wash usually shows a difference the same day. If a filter helps you, you will probably notice within a week or two. If nothing changes after a month, the filter is not solving your problem.
When to see a doctor
Hard water is unlikely to be the main cause of scalp or hair problems. See a doctor or dermatologist if:
- Your scalp is itchy, flaky, red or sore.
- Your hair is falling out or thinning.
- You have a rash or patches of dry, cracked skin that do not improve with moisturizer.
- Your skin stings or burns after showering.
FAQ
How do I know if my water is hard?
Check your local water supplier's report, or use a simple test strip. White scale on taps and shower heads is a strong clue.
Does a shower filter help hair loss?
There is no good evidence that shower filters reduce hair loss. Shedding and thinning have other causes that a doctor can check.
Does rinsing with bottled water help?
It can reduce mineral contact, but it is not practical for most people. A chelating shampoo is easier.
Is hard water bad for curly hair?
Mineral buildup can make curls look limp, dry and frizzy. Many people with curls find a monthly chelating wash helps.
Do I need a filter if I swim?
Pool chlorine is a bigger issue than tap water. Wet your hair with clean water before swimming, wear a cap and wash and condition afterward.
Sources
- Hardness of Water (US Geological Survey)
- Effects of Hard Water on Hair (PubMed Central, NIH)
- The structural implications of water hardness metal uptake by human hair (PubMed, NIH)
- A randomised controlled trial of ion-exchange water softeners for the treatment of eczema in children (PubMed, NIH)
- Randomized controlled pilot trial with ion-exchange water softeners to prevent eczema (SOFTER trial) (PubMed, NIH)