Short answer
Hard water stains are mineral deposits, mostly calcium and magnesium left behind when water dries. A mild acid such as diluted white vinegar or citric acid dissolves light spots in 10 to 15 minutes. Thick, layered build-up needs a degreasing clean, stronger descaling chemistry and a non-scratch pad. Either way the marks return unless the glass is sealed afterwards, because clean glass still holds water on its surface.
If your shower screen has gone from clear to cloudy, you are not cleaning it wrong. You are fighting chemistry: every time water dries on glass, it leaves behind whatever was dissolved in it. This guide covers what those marks are, how to get them off without damaging the glass, and the part most guides skip, which is why they come straight back.
First, work out what is on the glass
"Hard water stains" usually means more than one thing. Treat the wrong one and you will scrub for an hour with nothing to show for it.
| What you see | What it probably is | What removes it |
|---|---|---|
| White spots or rings that feel chalky | Mineral deposits (limescale): calcium and magnesium left when water dried | A mild acid for light spots; a purpose-made descaler for thick layers |
| A grey, greasy film that smears when wet | Soap scum: soap and shampoo reacting with the same minerals | A degreasing cleaner first, then an acid for the minerals underneath |
| Cloudiness nothing shifts, even on clean glass | Possibly etching: the glass surface itself has been attacked | Cleaning cannot reverse it (see the last section) |
Most screens that have been neglected for a while carry more than one: soap residue bonded into layers of minerals. That is why a single spray rarely does it. Two quick tests to tell them apart are in soap scum or hard water stains?
Light spots: the vinegar or citric acid method
For marks that are new and thin, where you can still see clearly through the glass, a mild household acid is enough. Calcium deposits dissolve in acid; that is the whole trick.
- Protect what is around the glass. Acids etch marble and other natural stone, and can dull some metal finishes. Cover stone ledges and keep the mix off fittings.
- Mix it. Equal parts white vinegar and warm water in a spray bottle, or a tablespoon of citric acid dissolved in about 500 ml of warm water.
- Give it time. Keep the glass wet for 10 to 15 minutes. On a vertical screen the liquid runs off, so press paper towels soaked in the mix onto the worst areas.
- Scrub gently. A non-scratch sponge, working from the top down.
- Rinse and dry completely. Rinse with clean water, then squeegee or dry with a microfibre cloth. If you let it drip dry, you are putting fresh spots straight back on.
Never mix an acid with bleach or a bleach-based bathroom cleaner. Together they release chlorine gas. Rinse between products and keep the bathroom ventilated.
Heavy, layered build-up
If vinegar makes no visible difference, the deposits have built up over months or years of wetting and drying, usually with soap residue locked in between the layers. A weak acid works too slowly on that. What it needs instead is:
- A degreasing clean first, so the soap film stops shielding the minerals.
- Stronger descaling chemistry made for the job, with enough contact time to work.
- Mechanical action from a non-scratch pad, one panel at a time.
- Care: gloves, ventilation, stone and fittings protected, and the product's own instructions followed exactly.
This is what the first three bottles in the Infinite Coatz kit are for: a clean, a strip and a scrub, each doing one job, before anything goes on the glass.
What not to do
- Steel wool, scouring powder or a kitchen scourer. They leave fine scratches, and scratched glass holds minerals even better than smooth glass.
- Scraping with a blade. Most shower screens are tempered glass, and a blade can drag a trapped grain of grit into a long scratch.
- Mixing products, above all acid with bleach.
- Leaving an acid to dry on the glass, the frame or the seals.
- Letting the glass drip dry at the end, which undoes the work.
Why the stains come back
Clean glass is not the same as protected glass. Bare glass attracts water: instead of forming beads, water spreads out into a thin film and sits there. When that film dries, it leaves a fresh layer of minerals, and with hard water the first spots can reappear within days.
Cleaning more often only treats the symptom. What changes the outcome is changing how water behaves on the surface. A water-repellent coating makes water bead up and run off, taking most of the minerals with it before they can dry in place. There is more on that in nano coating vs glass cleaner.
How the Infinite Coatz kit does it
The kit follows exactly this order: clean, strip, scrub, then seal. The first three bottles remove what is on the glass. The last step seals the surface with a 9H nano coating, so water beads instead of spreading, for up to two years depending on how hard your water is and how often the shower runs.
Two honest limits. You will still squeegee, but it becomes a quick pass rather than a scrub. And glass that has etched deeply can keep a faint shadow even when everything on top of it has come off.
Quick questions
Does vinegar damage shower glass?
Not the glass. Diluted white vinegar is safe on glass, but it can etch marble and other natural stone, and it is hard on some metal finishes and rubber seals if it is left on. Rinse it off when you are done.
Can hard water stains become permanent?
Yes. Left long enough, deposits can attack the surface of the glass itself. That is called etching, and at that point cleaning removes what sits on the glass but not the damage in it. It is the best reason to deal with build-up early. More in etched shower glass: can it be restored?
Will a water softener fix it?
A softener removes most of the hardness minerals from your water, so far fewer spots form. It is a bigger commitment (plumbing, salt, servicing) and it does nothing for stains that are already there.