Can a shower head water softener help hair and skin?

The main standard for these products is NSF/ANSI 177, "Shower Filtration Systems - Aesthetic Effects." Plumbing & Mechanical magazine's overview says the standard "establishes minimum certification requirements for shower filters: material safety, structural integrity, minimum flow rate, FAC reduction and literature." FAC means free available chlorine. To pass, a system "must reduce the influent challenge of 2.0 mg/l chlorine by 50 percent." The list has no hardness test. So a filter can carry the certification and still say nothing about whether it removes calcium or magnesium.

The article adds that the standard "is not a health effects standard," and that a shower filter is "not intended as a drinking water treatment system." A claim about softer skin or better hair on a shower head box is not something this certification checks.

Penn State Extension describes softening this way: "A water softener, also called an ion exchange unit, will effectively accomplish" the reduction of calcium and magnesium. The resin "releases its sodium ions and readily trades them for the calcium and magnesium ions." When the resin is full, "the resin is spent and will no longer soften water" until it is regenerated with a salt solution.

That last point is the problem for a shower head cartridge. Most cartridges have no brine tank and no drain, so they generally cannot regenerate. They work until the resin is full, then they stop softening.

Here is a simple estimate. Penn State's table of water use lists bathing and showering at "25-60 gal/use." The City of Phoenix's 2025 report lists hardness of 10 to 17.6 grains per gallon. Multiply the two and one shower carries roughly 250 to 1,050 grains of hardness. The estimate is arithmetic, not a measurement, but it shows the scale.

Now compare a cartridge's rated capacity, which is printed on good ones in grains. If a cartridge were rated for 5,000 grains, it would be spent after about 5 to 20 showers at those hardness levels, depending on your water and shower length. Scale it up to a household. If four people each shower once a day, that is four showers, or about 1,000 to 4,200 grains of hardness a day at Phoenix levels. The same hypothetical 5,000-grain cartridge would be spent in one to five days. That is arithmetic on an assumed rating, not a test of any product. It shows why capacity is the number to look for.

Cartridges that list no grain capacity give you no way to know how long they last, which is a reason to be careful with them. Penn State's sample whole-house softener has a capacity of 20,000 grains per regeneration and then regenerates automatically, which is the difference between a plumbed-in system and a cartridge.

We did not find a trial of shower head softeners on hair or skin. The best evidence on softened water and skin is the whole-house kind, and it is not encouraging. A randomised trial in PLOS Medicine put ion-exchange softeners in the homes of 336 children with eczema. It found that "water softeners provided no additional benefit to usual care in this study population." Our page on whether soft water is better for your skin covers what that trial did and did not test.

Some people do notice a difference after softening because hard water leaves a film. Penn State says "hard water leaves scales on pots, soap films on skin, and detergent curds in the washing machine." A reduction in soap film is a plausible reason skin feels different. But that is an impression, and a small cartridge that is already full will not deliver it.

### Chlorine filters are a different product

Some shower filters are sold for chlorine, not hardness, and that is a separate question. The Plumbing & Mechanical article notes that "manufacturers of chlorine filters for showers say users can notice a difference after one use" and that "skin is left less dry." Those are manufacturer statements, and the article itself says the standard is "not a health effects standard." The certification also comes with a caution: the system "has not been evaluated for free available chlorine reduction performance in the presence of chloramines," and buyers should "contact your local water utility to determine if chloramines are used in treating your water." So a chlorine filter is a chlorine product. It is not a softener, whatever the box calls it.

### Scale on the shower head itself

A shower head does get scale in hard water. Battelle's accelerated tests for the Water Quality Research Foundation found that low-flow showerheads on unsoftened water "clogged after an average of 3,203 gallons of water flow through them," while the ones on softened water "made it through the testing without any problems." That was whole-house softened water, and the test sped up scaling, but it points the same way. The place to deal with scale is upstream of the fixtures.

Start with the facts about your water, then choose a fix that matches.

1. 1Find out if hardness is your problem. Phoenix's range is well above the point where scale shows. Our page on how hard Phoenix water is explains the number, and a test strip tells you yours.
2. 2Read the label and the manual. NSF/ANSI 177 requires the owner's manual to give the rated capacity, rated service flow rate, maximum working pressure and maximum operating temperature. If a shower head product lists a rated grain capacity and how to recharge it, you can judge it. If it lists only chlorine reduction, it is a chlorine filter.
3. 3Consider the whole house. A properly sized softener treats every fixture. Our page on the benefits of a whole-house softener separates the proven benefits from the unproven ones, and choosing the right size softener covers sizing.
4. 4Do not use a shower filter for drinking water. Shower filters are "not intended as a drinking water treatment system." For drinking water, see water softener versus reverse osmosis.
5. 5Ask a plumber to look at the fixtures. If a shower head is crusted or the flow has dropped, a plumber can check whether scale is the cause and what to do about it, and can tell you whether the hardness in your house justifies treatment at the main.

HQ Plumbing & Air is licensed and insured, and can test your water hardness and tell you whether a softener would help. We offer free estimates and upfront pricing.