We may earn a commission when you buy through our links; it never affects our scores.
The short answer
How to remove hard water stains: dissolve them with a mild acid, then rinse. White vinegar works on glass, tile, porcelain, and chrome; Kohler suggests a 50/50 mix of vinegar and warm water on a towel for 5 to 10 minutes for faucet buildup. For heavier scale, a descaler such as CLR works faster, but follow the label: CLR says dilute it 1:1 and never leave it on longer than 2 minutes. Never use acid on marble or other natural stone, and never mix an acid cleaner with bleach.
What are hard water stains?
They’re mineral deposits. Hard water carries dissolved calcium and magnesium, and when it heats or evaporates, solid deposits of calcium carbonate are left behind. With soap, hard water also forms a sticky soap curd, the film on shower glass. Hardness isn’t a health concern, according to the U.S. Geological Survey, just a nuisance. Rust-colored marks are a different problem: iron, which leaves yellow, red, or brown stains.
| USGS category | Hardness (mg/L as calcium carbonate) | Grains per gallon (about) |
|---|---|---|
| Soft | 0 to 60 | Under 3.5 |
| Moderately hard | 61 to 120 | 3.5 to 7 |
| Hard | 121 to 180 | 7 to 10.5 |
| Very hard | Over 180 | Over 10.5 |
From the USGS. One grain per gallon equals approximately 17 mg/L.
What removes hard water stains?
- White vinegar: FDA guidance sets vinegar at at least 4% acetic acid. Cheap, safe on most hard surfaces, and slow on thick scale.
- CLR: Mix equal parts CLR and warm water, leave no longer than 2 minutes, and rinse with cold water. Don’t use it on natural stone, marble, sealed or painted surfaces, brass, copper, aluminum, or cast iron.
- Lime-A-Way: A sulfamic acid cleaner labeled corrosive. Its label says not to use it on natural marble or stone, colored grout, or painted surfaces, and that it may etch older porcelain and ceramic tile.
- Citric acid: Another mild acid, sold as a powder; dissolve it in warm water.
How do you remove hard water stains from each surface?
| Surface | What to use | Watch out for |
|---|---|---|
| Glass and shower doors | Vinegar spray or a vinegar-soaked towel; wipe and rinse; a non-scratch pad for film | Squeegee afterwards to slow new spots |
| Toilet bowl | An acid descaler on the ring; follow the label for contact time | Never combine with bleach or a bleach bowl cleaner |
| Faucets and chrome | 50/50 vinegar and warm water on a towel, 5 to 10 minutes | Wipe with a soft cloth; check the maker’s finish guidance |
| Tile and porcelain | Vinegar or a diluted descaler; rinse well | Lime-A-Way warns it may etch older porcelain and tile, and avoid colored grout (label) |
| Marble, travertine, limestone | A stone-safe, pH-neutral cleaner | Acids such as vinegar dissolve these stones and leave etch marks |
| Kettles and coffee makers | Vinegar or citric acid per the maker’s descaling instructions | Rinse several times before use |
Can you mix vinegar and bleach to clean hard water stains?
No. The New Jersey Department of Health warns that when chlorine bleach is mixed with an acid, chlorine gas is produced, and at higher levels it can cause severe breathing trouble and lung damage. Its alert describes a restaurant worker who died after a lime remover was mixed with bleach in a dishwasher. CLR and Lime-A-Way both say not to mix their products with bleach. If someone breathes in fumes, call Poison Help at 1-800-222-1222.
Why won’t some hard water stains come off?
Long-standing deposits can etch glass, and acid can etch stone. On marble, the GSA says etch marks need re-polishing; no cleaner restores them. If a mark doesn’t feel rough or raised, it may be etching rather than scale.
How do you stop hard water stains coming back?
- Dry surfaces: Squeegee shower glass and wipe fixtures after use, so water doesn’t evaporate on them.
- Soften the water: An ion exchange softener removes hardness. Look for one certified to NSF/ANSI 44 by NSF International, IAPMO R&T, or WQA, such as the Aquasana SimplySoft or the Kenmore 350. Softening adds sodium: Aquasana, which makes softeners, says it adds about 7.5 mg per quart for each grain of hardness removed.
- Salt-free devices: UNL Extension says physical conditioners do not remove the hardness, and their effectiveness hasn’t been scientifically assessed. SpringWell’s FutureSoft is one; no certifier lists it.
- Test first: A hardness test shows whether a softener is worth it. See our hard water guide.
Aquasana SimplySoft
Kenmore 350
Tap Score Advanced Home Water Test
Common questions
What are hard water stains?
Mineral deposits of calcium and magnesium, left when hard water heats or evaporates.
How do I remove hard water stains from glass?
Spray or soak with white vinegar, let it sit, then wipe and rinse. For heavy scale, use a descaler and follow the label: CLR says no longer than 2 minutes.
How do I get a hard water ring out of a toilet?
Apply an acid descaler to the ring per the label, scrub, and flush. Never combine it with bleach.
Can I use vinegar on marble or granite?
Not on marble, travertine, or limestone: acids dissolve them and leave etch marks. Use a stone-safe cleaner.
Does a water softener stop hard water stains?
Yes, an ion exchange softener removes the hardness that causes them; our picks are the Aquasana SimplySoft and the Kenmore 350, both certified to NSF/ANSI 44. Salt-free devices don’t remove hardness. See our best water filter for hard water guide.
Sources
Prices as of November 1, 2026. Product prices and availability are accurate as of the date/time indicated and are subject to change. As an Amazon Associate we earn from qualifying purchases.