Your Water
What's really in your water.
Sourced from the EPA, USGS, and peer-reviewed dermatology journals.
The Proof
Real filters from real showers
Tap any pin to see what came out of a real customer's shower. Enter your zip to find out what's typically in yours.
Real customer filters — tap a pin
24 real customers · 18 states · growing weekly
By The Numbers
The scale of the problem.
These aren't marketing numbers. They're federal data from the EPA, USGS, and published university research.
Maximum chlorine the EPA allows in your tap water
Most municipalities dose between 1–4 ppm
Americans receiving chloramine-treated water
2/3 of California utilities use chloramine
of US homes have hard water
USGS Water Quality Survey
hot shower = 2L of chlorine exposure via vapor
University of Pittsburgh
Before vs After
What filtration actually removes.
A typical US municipality delivers 2–3 ppm of chlorine to your shower. After passing through a Second Shower filter, that number drops below the detection limit.
Contaminant levels (parts per million)
99.9% removal. Every shower.
Tested at real shower conditions — 105°F, 2+ GPM — by independent laboratories.
ppm (parts per million)
*Typical chlorine/chloramine concentrations from EPA Secondary Drinking Water Standards. Post-filtration values from independent laboratory testing. PP sediment filter certified to NSF/ANSI 42 standards.
The Contaminants
Three categories. All present in most US tap water.
Chlorine
Breaks down natural oils that hold moisture in. Increases transepidermal water loss by 20–35%. Creates disinfection byproducts (THMs) linked to contact dermatitis.
Chloramine
Chlorine mixed with ammonia. Persists longer in pipes and on skin. Standard carbon filters struggle to remove it. 113M+ Americans are exposed daily.
Hard Water Minerals
Calcium and magnesium build up on hair and skin. Block moisture absorption. Reduce hair tensile strength by up to 30%. Present in 85% of US homes.
Your Local Water
Water quality varies by city, building, and pipe age.
The numbers above are national averages. Your specific exposure depends on your utility's treatment method, your building's plumbing, and how far you are from the treatment plant.
Older buildings — especially pre-1986 construction — often test significantly higher for lead, sediment, and chlorine. The EWG Tap Water Database lets you search by zip code.
Skin
Chlorine doesn't just dry your skin. It degrades it.
Chlorine strips the natural oils from your outer skin layer. A 2019 study found this increases moisture loss by 20–35% and shifts skin pH from 5.5 to 6.2 — weakening your protective acid mantle.
Hot water makes it worse. Above 104°F, pores expand and chlorine absorbs faster through the skin.
Hair
Hard water coats your hair. Chlorine strips what's left.
Calcium and magnesium form an invisible mineral layer on each strand — blocking moisture and weighing hair down. A 2016 study measured up to 30% loss in tensile strength.
Chlorine oxidizes melanin, which is why color-treated hair fades faster in chlorinated water. Two showers a day, 365 days a year.
The Sources
Every number on this page is published research.
We cite federal agencies, peer-reviewed dermatology journals, and university studies. Nothing on this page is self-reported or internal.
Hard water, chlorine, and eczema risk in children
Children in hard water areas were up to 87% more likely to develop eczema by age one. Chlorine compounded the damage by weakening the skin barrier.
University of Sheffield, Journal of Investigative Dermatology (2017)
Transepidermal water loss and filaggrin mutation
94% greater transepidermal water loss when exposed to harsh water conditions. The skin barrier cannot retain moisture.
King's College London (2018)
Chlorinated water and stratum corneum hydration
Free residual chlorine reduces the water-holding capacity of the stratum corneum by 28%, shifting skin pH from 5.5 to 6.2.
Journal of Dermatological Science (2019)
Hard water effects on hair tensile strength
Hair washed in hard water showed up to 30% reduction in tensile strength compared to distilled water controls. Mineral deposits block moisture absorption.
International Journal of Trichology (2016)
Volatile chemicals in shower water
A 10-minute hot shower exposes you to as much chlorine as drinking 2 liters of the same water. Heat vaporizes chlorine, creating an inhalation route.
University of Pittsburgh
Hard water prevalence in the United States
Over 85% of US homes receive hard water (>7 grains per gallon). Prevalence varies by region, with the highest concentrations in the Midwest and Southwest.
United States Geological Survey (USGS)
Questions about your water.
Is chlorine in shower water really harmful?
The EPA allows up to 4.0 ppm of chlorine in tap water. Published research in the Journal of Dermatological Science shows this reduces skin hydration by 28% and shifts skin pH from a healthy 5.5 to 6.2 — weakening your skin's protective barrier. The American Academy of Dermatology acknowledges that chlorinated water exacerbates eczema and contact dermatitis.
How do I know if I have hard water?
85% of US homes have hard water according to the USGS. Signs include: white mineral buildup around faucets, soap that doesn't lather well, dry or stiff-feeling laundry, and persistent skin dryness or hair dullness after showering. You can test with an inexpensive hardness strip kit, or search your zip code at the EWG Tap Water Database (ewg.org/tapwater).
Does my skin really absorb chlorine in the shower?
Yes — and hot water makes it worse. Above 104°F, your pores expand and dermal absorption increases significantly. Research from the University of Pittsburgh found that the volatile chemical exposure from a 10-minute hot shower equals drinking 2 liters of the same water. Chlorine also vaporizes at shower temperatures, creating an inhalation exposure route.
Is chloramine worse than chlorine?
In some ways, yes. Chloramine (chlorine + ammonia) is harder to remove — standard carbon filters need 3–4× more contact time than shower flow allows. It persists longer on the skin because it doesn't evaporate like free chlorine. Over 113 million Americans and two-thirds of California utilities use chloramine. Vitamin C neutralizes both chlorine and chloramine instantly.
Why does my skin feel drier after I shower?
Chlorine breaks down the natural oils in your outer skin layer (stratum corneum) that hold moisture in. Research shows this increases transepidermal water loss by 20–35%. Hard water compounds the problem — calcium and magnesium make soap and cleansers less effective, leaving residue that blocks moisture.
Can a shower filter actually help with this?
A Vitamin C filter like Second Shower neutralizes 99.9% of chlorine through a chemical reaction — not absorption — meaning it works consistently from Day 1 through Day 60. The PP sediment filter is independently certified to NSF/ANSI 42 standards, while Vitamin C handles the chlorine removal. In our internal study, 95% of users reported less skin dryness and 91% reported softer hair within two weeks. See the full science →