If you have moved house and suddenly your car spots after every wash, your technique has not got worse. Your water has changed.
What a water spot actually is
Tap water carries dissolved minerals, mostly calcium and magnesium. When a droplet dries on paint, the water evaporates and the minerals stay behind as a visible ring. That is a deposit, and it will wash off if you catch it.
Leave the same droplet in hot sun and something worse happens: the concentrated mineral solution etches into the clear coat and leaves a mark in the surface. That is etching, and washing will not touch it — it needs a dedicated water spot remover or machine polishing.
Why the UK varies so much
Water hardness follows geology. Broadly, areas over chalk and limestone — much of the south and east of England — have hard water. Areas over granite and older rock — large parts of Scotland, Wales, the north west and the south west — tend to be soft.
The practical test costs nothing: if your kettle furs up, your shower screen spots and soap does not lather easily, you are in a hard water area and your car will spot readily.
Working around hard water
- Never wash in direct sun. This matters far more in hard water areas — you are racing evaporation.
- Work panel by panel. Wash and rinse one section, dry it, then move on. Do not soap the whole car and come back to it.
- Sheet the water off. Free-flowing water removes most of the volume before drying.
- Dry immediately and completely. Air drying is not an option in hard water areas.
- Use a drying aid. It speeds up drying and adds lubrication at the same time.
- Get water out of the gaps. Mirrors, badges, grilles and shuts drip onto dry paint and leave the worst spots of all.
Protection helps, but is not immunity
A hydrophobic surface sheds water into fewer, larger droplets that run off rather than sitting. Less standing water means fewer spots. But a droplet that does stay put on a coated panel still leaves minerals behind when it dries — protection reduces the problem, it does not remove it.
Removing spots that are already there
Fresh deposits usually come off with a wash or a quick detailer. Older, bonded deposits need an acidic water spot remover, which dissolves the mineral rather than abrading it. Etched spots that have gone into the clear coat need polishing.
A quick test: wet the panel. If the marks vanish while wet and come back as it dries, they are surface deposits. If they are still visible when the panel is wet, the clear coat is etched.
We make removers for both paint and glass in the paint maintenance and glass cleaning ranges.
The one habit that fixes most of it
Do not let water dry on the car. That is genuinely the whole thing. Every other piece of advice here is a way of making that easier.
Before you start
Always read the label on the product you are using and follow the instructions on it for dilution, application and safety. Work in the shade on cool paint, and test anything new on a small, hidden area first — particularly on trim, wraps and finishes you are not familiar with.
Not sure which product fits the job? SWAG Fast Lane asks three quick questions and puts the right kit together for you.