Does the United States have hard water? Yes — most of it. USGS estimates suggest around 85% of American homes have hard water to some degree. The good news: you can check your exact water hardness by ZIP code in about a minute, for free. Here's how — and what your number means for your skin.
In the UK? The UK version with postcode checking is here: check your water hardness by postcode.
The US hardness scale (PPM and gpg)
US water hardness is reported in two units: PPM (parts per million, also written mg/L as CaCO₃) and gpg (grains per gallon — the one most US water suppliers use). The conversion: 1 gpg = 17.1 PPM.
Skincare generally notices from around 120 PPM (7 gpg) upwards — and from 180 PPM (10.5 gpg), most skin types will feel it: tightness after washing, products that seem to sit on top, congestion that doesn't shift.
How to check your water hardness by ZIP code — 3 free ways
- Your water supplier's Consumer Confidence Report (CCR). Every US public water supplier publishes one annually. Search "consumer confidence report" + your supplier's name (or your city + "water quality report"), then look for "hardness" — reported in gpg, PPM, or mg/L.
- The EWG Tap Water Database. Enter your ZIP code at the Environmental Working Group's tap water database and it pulls your supplier's latest testing data — including the minerals behind hardness.
- The USGS water hardness map. The US Geological Survey publishes a national hardness map — useful for a quick regional read, though your supplier's report is more precise for your address.
One-minute version: the EWG database is the fastest. Your supplier's CCR is the most accurate.
The hardest-water regions in the US
Hard water concentrates in the Southwest, Florida, and parts of the Midwest — the states where water travels through limestone and mineral-rich geology. Areas known for very hard water include much of Texas, Arizona, Nevada, Utah, Florida, and Southern California, plus pockets across the Midwest (Indiana, Kansas, Oklahoma, Illinois). Las Vegas, Phoenix, San Antonio and Tampa regularly sit among the hardest-water cities.
But hardness varies city by city — sometimes street by street. Your ZIP code check beats any map.
What your number means for your skin
The short version: hard water leaves a mineral residue on skin (the same soap scum you see on taps), raises surface pH, and stresses the skin barrier — conditions that make breakouts worse and existing acne harder to shift. The full research picture, including what dermatology does and doesn't show, is here: what the dermatology evidence actually says.
If your skin changed after a move — tighter after cleansing, tiny bumps that don't shift, flare-ups along the hairline and jaw — that's the classic hard-water pattern. The signs checklist is here: is it your water, not your products?
What to do about it
The highest-leverage change is your cleanser — the step where hard water touches your skin every day. In hard water, the wrong cleanser doesn't just underperform: its cleansing agents react with the minerals and leave more residue behind.
That's why we made the Barrier Restoring Creamy Cleanser — a cream-to-milk, chelating formula that lifts mineral residue and daily impurities without the harsh surfactants the research points at. Used with the dry cleanse method (cleanser on dry skin first, before water), it's the single biggest upgrade for hard-water skin. The complete routine is here: the skincare routine you need if you have hard water.
US shipping: tracked UPS delivery in 5–14 business days — £8.99, or free over £90. No customs fees: US orders under $800 arrive duty-free, so what you pay at checkout is final. The complete kit is here: explore the hard water collection.
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