Do Shower Filters Work? What They Remove, and What They Do Not
Short answer: some do, for chlorine. Good shower filters reduce chlorine, and a few are certified to NSF/ANSI 177 to prove it. In independent testing, the certified Weddell Duo took chlorine from 1.68 PPM to zero, while the popular eskiin showed no reduction at all. No shower filter softens water: none remove meaningful calcium and magnesium, so they will not fix hard water hair, skin or limescale. Most are also not certified for chloramine, which many US cities use.
What Shower Filters Remove
| Substance | Typical Shower Filter | NSF/ANSI 177 Certified Filter |
|---|---|---|
| Free chlorine | Often reduced, but unverified | Yes, the certified claim |
| Chloramine | Partial at best | Not covered by certification |
| Disinfection byproducts (THMs) | Varies; carbon block helps | Not covered by certification |
| Calcium and magnesium (hardness) | No | No |
| Limescale | No | No |
| Lead, PFAS, microplastics | Brand claims only | Not covered by certification |
NSF/ANSI 177 is the standard for shower filtration. When we checked NSF's official listing in October 2026, every shower filter on it was certified for the same thing: free available chlorine reduction. Among brands we cover, the Weddell Duo and the Jolie are on the list; Canopy, AquaBliss, eskiin and Sprite were not.
What Testing Shows
Water Filter Guru, an independent reviewer, has tested many shower filters by measuring water before and after. Their results show how wide the range is:
| Filter | Chlorine Before | Chlorine After | NSF/ANSI 177 |
|---|---|---|---|
| Weddell Duo | 1.68 PPM | 0 PPM | Certified |
| Jolie | Chlorine eliminated | Certified | |
| Canopy | Chlorine eliminated | Not listed | |
| eskiin | 1.68 PPM | 1.79 PPM | Not listed |
The lesson: "shower filter" is not one thing. Some remove all measurable chlorine; some do nothing. Certification or published independent testing is the best way to tell them apart. You can also test any shower filter at home with chlorine strips.
Filter Media Explained
- KDF-55 (copper-zinc): reduces chlorine through an oxidation-reduction reaction. Used in Jolie and Canopy. Independent testing has shown zinc can rise in filtered water from KDF media.
- Calcium sulfite: reacts with chlorine quickly, which suits fast-moving shower water. Used in Jolie, Canopy and AquaBliss.
- Activated carbon and carbon block: adsorb chlorine and some organic compounds. A dense carbon block, as in the Weddell Duo, gave the best results on disinfection byproducts in testing.
- Vitamin C (ascorbic acid): neutralizes chlorine and chloramine, but cartridges tend to be used up quickly.
- Redox media: a general term for media that work by oxidation-reduction, used in AquaBliss.
What Shower Filters Cannot Do
They cannot soften water. Removing calcium and magnesium requires ion exchange, the technology in a water softener, at a capacity no shower cartridge has. In Water Filter Guru's test of the Weddell Duo, hardness went from 128.19 to 125.59 PPM, essentially unchanged. If your hair feels coated or your shower glass is covered in white scale, a shower filter will not fix it.
For hard water minerals on hair, use a chelating shampoo. To stop minerals at the source, install a water softener. For limescale on fixtures, see how to remove limescale.
The Chloramine Problem
Many US utilities disinfect with chloramine, a combination of chlorine and ammonia, instead of chlorine. Chloramine is more stable, which is good for pipes but harder for fast-acting shower media to break down. NSF/ANSI 177 certification covers free chlorine, not chloramine, and in independent testing even the certified Weddell Duo did not reduce chloramine. Los Angeles, for example, uses chloramine (see our LA guide), while Chicago uses chlorine (see our Chicago guide). Check your utility's annual water quality report before buying a filter.
Do They Help Hair and Skin?
Many people find chlorinated water leaves skin tight and hair dry, and a filter that removes chlorine can make showers feel gentler. But the stronger research on skin is about hardness, not chlorine. Studies link hard water to higher eczema risk in children and to more soap residue left on skin, and a 336-child trial found that adding a water softener did not improve existing eczema beyond usual care. A shower filter does not touch hardness. See hard water and skin and hard water and hair for the evidence.
When a Shower Filter Is Worth It
- Worth it: your city uses chlorine, you notice a chlorine smell, and chlorine seems to bother your skin or hair. Choose a certified filter.
- Maybe: your city uses chloramine. Benefits will be smaller; manage expectations.
- Not worth it for: hard water hair, limescale, private well water without chlorine, or treating hair loss.
Ready to choose? See our best shower filters for hair and how often to change a shower filter.
How to Choose a Shower Filter That Works
- Check your water report for chlorine or chloramine, and test your hardness.
- Look up the filter on NSF's listing for NSF/ANSI 177. "Tested to" is not the same as certified.
- Look for published independent tests showing chlorine before and after.
- Count the ongoing cost: cartridges every 3 months versus every 5 to 6 months adds up.
- Test it yourself with chlorine strips after installing.
Frequently Asked Questions
Some do, for chlorine. Certified filters such as the Weddell Duo and Jolie reduced chlorine in independent testing, while some popular filters showed no reduction. No shower filter softens water.
No. Shower filters do not remove meaningful amounts of calcium and magnesium. Only an ion-exchange water softener removes hardness.
Not reliably. NSF/ANSI 177 certification covers free chlorine, and in independent testing the certified Weddell Duo did not reduce chloramine. Vitamin C media can neutralize chloramine but are used up quickly.
As of NSF's listing checked in October 2026, the Weddell Duo and the Jolie Filtered Showerhead are certified to NSF/ANSI 177 for free chlorine reduction among the brands we cover.
There is no evidence that shower filters treat hair loss. If shedding is a concern, see a dermatologist.
Yes. Compare chlorine test strip readings from the bath tap and from the shower through the filter. A working filter shows a clearly lower reading.
Vitamin C neutralizes both chlorine and chloramine, which helps in chloramine cities, but the cartridges tend to be used up quickly. Before buying one, check whether that exact product appears on NSF's NSF/ANSI 177 listing.
They can if chlorine is part of the cause, since certified filters reduce chlorine. But research links dry skin and eczema risk more strongly to water hardness, which shower filters do not change. A good moisturizer and lukewarm showers help too.
Possibly. A softener removes hardness, not chlorine. If your city uses chlorine and it bothers you, a certified shower filter adds chlorine reduction on top of softened water.
Last updated: October 2026. Sources: NSF/ANSI 177 listing; Water Filter Guru reviews of Weddell Duo, eskiin and Canopy vs Jolie.