There is a basic rule to follow if you want to put a stop to water spots on your car windows: never allow water with a high mineral content to dry on the glass. Do your washing in the shade with clean water, make sure the windscreen and mirrors are dried at once and for better rain visibility put on a water-repellent of some kind.
I am Richard Redfern and I have been taught by experience that a car can be spotless but still look as rough as guts when its windows have mineral deposits from drying. In Australia you have to contend with hard water in places, dust, road spray, the odd downpour and quite a bit of sun, all of which make for very obstinate water marks. But there is no need for a garage full of enigmatic bottles to prevent them; in fact prevention is far simpler than trying to put things right afterwards.
What Causes Water Spots On Car Windows?
When droplets evaporate they leave their residue in the form of minerals and salts. The water is gone but you are left with cloudy circles or streaks on the car glass. Hot glass and the direct rays of the sun will exacerbate the issue as the droplets dry. Even a hasty rinse after a drive in the rain can put marks on your windscreen since the water has gathered up its share of pollution and grime along the way. Proper drying car windows after washing can help prevent these marks.
Hard Water Leaves Deposits
With hard water you have more dissolved minerals in play and they will bond to the surface of the glass upon drying. Bore or tank water and certain local supplies are more of a nuisance than filtered water, but any wash water will mark the glass if you do not get to it with a cloth in time.
A few mineral deposits may seem of no consequence. Yet over time they build up into a roughness that will catch dirt and make wipers chatter, which is less than ideal on the Stuart Highway come a summer storm.
Rain Is Not Always Clean
Rain leaves its mark because it is not exactly pure; it picks up what is in the air as it falls and the first rain after a long dry is apt to be dirty. Then you have the oily film and grit from road spray.
Before you put in the effort of a wash it is worth looking at the official forecast from the Australian Bureau of Meteorology. Unless you fancy having to dry the car over again, do not start a wash just before the rain comes in.
Prevent Spots During Washing
You can stave off water spots by being in control of the conditions. Find a cool spot in the shade, work on a section at a time and let the glass stay wet until you put a towel to it.
Try washing on a hot driveway at midday and you will be in trouble; the water will flash off and you will have a set of tidy little circles as if seagulls have been at it.
Choose The Right Conditions
Do it under good shade or in the late afternoon and early morning when the glass is cool. A hot windscreen means you should move the car or hold off; the sun will see to it that a panel dries while you are still rinsing.
Rinse top to bottom and have separate gear for the wheels, brake dust and the like will scratch paint and glass. You do not need a lot of products so much as a bucket, mitt and towels that are actually clean.
Control The Water
If the tap water in your area is hard, a final rinse with distilled or filtered water will cut down on the mineral residue. It is not a must every time but it helps when you find ordinary water is causing spots.
Make sure the shampoo does not dry on the windscreen. Give it a good rinse, around the mirror edges, window rubbers, roof channels and wiper blades where water is held and then released in new streaks.
- Wash in the shade with cool glass.
- Clean the windscreen to finish.
- Have a microfibre towel to hand before you pick up the hose.
- Dry the glass and the mirrors and rubbers too.
- Take a good look at the car from all sides before you put the towels away.
Dry Glass Before It Dries
The moment you have given the car its last rinse is the time to dry the windows. Packing the bucket, making a coffee or ascertaining why the neighbour’s dog has such an opinion of you is no time to let the car be.
A proper drying routine will have the water gone before evaporation can put down its mineral deposits and it is a good way to put your eye on any streaks for easy correction.
Use A Two-Towel Method
Take a large microfibre towel of good absorbency and put most of the water with it. Then a second one, clean and dry, for the mirrors, side windows and windscreen.
Go from top to bottom on the glass. Make sure to turn the towel so dirty water is not being put onto a part you have just cleaned; wring it out or put it aside when it is full. A saturated towel is only going to push water about.
Check The Hidden Water
Open up the doors and have a look at the window channels. The lower edges of the side windows, mirror housings and the space under the wipers should be dried off, as they are apt to let some water go in the first few kilometres.
Once done, putter around the block at a slow pace and give the glass another once over. Should you see water coming from the roof channel or a mirror, pull over and deal with it. It does not matter how small the mark or how confident one feels, do not attempt to clean the windscreen in motion.
Stop Spots After Rain
Rain is not the whole story when it comes to water spots on a car after a shower; road film and dust on a dirty body will make ordinary droplets into something more tenacious. If the car is in order, a soft microfibre will do to get fresh rainwater off when it is safe to do so. Do not dry-wipe a dirty car though, the grit will scratch the paint and perhaps the glass.
Use A Safe Rain Routine
Rinse the loose dirt first. Do your wiping in the shade with a clean towel, the upper side windows, mirrors and windscreen in particular where droplets like to congregate. In northern Australia the wet season brings sudden storms and humidity that will call for this more often. Out in the Pilbara or Red Centre the sun is intense enough to dry a droplet in no time and dust is thick in the dry, so one has to be mindful of timing.
Improve Rain Visibility
There is value in a water-repellent treatment to get the rain to bead and run across the glass for better visibility when up to speed, but it will not do anything for oil, dirt or what minerals are already there. A hydrophobic coating is at its best on glass that has been put through a proper cleaning.
Wiper blades are important too; if they are worn they will leave a smear on the windscreen and make a clean surface appear otherwise. Put in new ones and see the rubber is clear of any residue.
Make Car Glass Water Resistant
Marketing will tell you one thing but in the end preparation is what makes car windows water resistant. A sealant or hydrophobic product can lessen the hold water has on the surface but it is not going to prevent every mark.
Beading is fine as the droplets are more inclined to move off, yet if left in the sun they will become small mineral circles. Consider water repellency an aid to your vision, not an alternative to a wash and dry.
Prepare Before Applying
Put some glass cleaner to the surface with a lint-free microfibre to get rid of any old product, grease or road film. Gritty feeling? An automotive clay bar will lift the bonded contamination.
Heavier deposits may need a glass polish, used as directed and with due care to keep any abrasives from the painted trim and seals.
Apply In Suitable Weather
Do not apply a water-repellent in the sun and never right before a rain if the label says it needs to cure. Cool, dry glass is the way to go. Follow the instructions on coverage and buffing.
Get in the driver’s seat and have a good look at the windscreen; if it is hazy or smeary, clear it up. You do not want to be driving at night with glare from a treatment that was supposed to be an improvement.
Compare Glass Repellent Options
Durability, cost and how easy it is to remove are all factors in choosing a product, so let your driving conditions be the guide rather than the boldest label. The one you can put on and maintain without trouble is the best.
For the Australian motorist, there is no shortage of automotive glass cleaners and water-repellents to be had from hardware stores, motoring retailers or a specialist detailer. A word of advice when you put in a search for car window cleaner at Bunnings: read the label. Some household brands have additives you do not want on your vehicle’s glass or trim.
| Option | Best For | What To Expect | Main Caution |
|---|---|---|---|
| Standard automotive glass cleaner | Routine work | Gets rid of dust, film and fingerprints | Will not put up a permanent defence against water |
| Glass sealant | Regular wet-weather or highway driving | Makes the surface more resistant to water | The glass must be dry and clean to begin with |
| Hydrophobic glass coating | Better rain visibility and more pronounced water beading | Can improve visibility when correctly applied | Overdoing it can create a haze |
| Glass polish | Mineral deposits and bonded contamination | Can restore smoothness | Requires care and controlled pressure |
Choose By Driving Conditions
Country drivers will put up with their share of road spray, insects and dust; here the ease of maintenance is often of more consequence than durability. Those in the city are more likely to be concerned with an oily film or a downpour after a hot day and the perils of parking under trees.
Add salt residue to the list for coastal drivers. Salt dries into marks and mixes with the grime on the road. After a trip to the beach, or any time the car has been on unsealed roads or close to tidal water, give the mirrors and glass a good rinse.
Remove Existing Glass Marks
How to remove water spots is a matter of how old and bad they are. The rule is to begin with the mildest approach and only put in more strength if the deposit will not budge.
Wash and dry the glass to start off with, then put some automotive cleaner to a microfibre towel. Should the marks persist, a little white vinegar solution will suffice on an inconspicuous patch before you wipe with clean water. Make sure none of it is left to dry on any rubber, paint or sensitive trim.
Escalate Carefully
When faced with tenacious mineral deposits, a purpose-made water-spot remover or glass polish is called for. Work on glass that is cool and adhere to what the manufacturer says. Put aside any razor blade or scouring pad unless you know the risks and it is made for the job.
Mirrors are another story. With their plastic housings, narrow edges and coatings they are prone to damage, so put the product on the towel, do not drench the mirror assembly.
Know When To Stop
If you have polished and cleaned to no avail, the mark is probably etched in. Any deep etching calls for a professional or a new piece of glass. Let an expert have a look at any night-time glare, cracks or scratches that will not go away.
Avoid These Common Mistakes
You see it all the time. People do a thorough wash and then in the last five minutes let the water stand on the glass while they put the car away or take a call. Or they think a water-repellent is some kind of magic shield. There is no denying that protection means less maintenance, but it will not put the car beyond the reach of hard water, dust, rain and road spray.
- Washing in the full sun or on glass that is hot to the touch.
- One towel for the wheels, paint, mirrors and glass alike.
- Putting a coating down over old residue, mineral deposits or grease.
- A dry wipe on some gritty glass after a shower of rain.
- Overlooking wiper blades that have a tendency to chatter or smear.
- Letting the roof channels run off once the glass has been put right.
Frequently Asked Questions
Australian drivers with an eye for poor visibility in the rain or hard water marks are wont to ask these questions. The answers I give are straightforward enough, yet one rule is always in evidence: let the droplets evaporate only after the glass is properly dried.
How Can I Remove Water Marks From My Car Windows?
Start by washing and drying the glass, follow up with an automotive cleaner. Should any marks be left, a polish or water-spot remover will do on cool glass. Light mineral deposits can be dealt with by a solution of white vinegar (diluted), provided you keep it from the trim, rubber and paint and give it a rinse when done.
Why Are There Water Spots On My Car After It Rains?
Before they dry the rain will have picked up its share of dust, pollution and grime from the road. Park in the sun and evaporation will put the minerals and residue where you can see them. Worn wipers and a soiled surface do not help.
How Can I Make Car Windows Water Resistant?
Decontaminate and clean the glass, see to any deposits and then put on a hydrophobic coating or sealant as the instructions dictate. Do not drive until you have seen there is no haze and the glass has cured. Once the water ceases to bead with any consistency, it is time to reapply.
What Is The Best Car Glass Water Repellent?
That is a matter of what one is prepared to spend and the conditions under which one drives. A professional grade coating has its place for those on wet highways for long stretches, a more basic treatment for everyday use. But no product will save you from spotting if you let mineral laden water dry on the glass.
Can Vinegar Damage Automotive Glass?
The glass can stand a well diluted solution of vinegar, but the same cannot be said for the coatings, rubber, paint and trim around it. Be sparing with it, test in an inconspicuous spot and rinse well. Under no circumstances should it be combined with bleach or the like.
Keep The Windscreen Clear
Preventing water spots is not complicated. Wash the glass while it is cool, a good rinse, dry it at once and apply protection when the surface is truly clean. You will find that holds up in the heat of Adelaide, in the country with all the dust, in coastal salt or during a Top End storm.
If you have a day to put the car in order, make the front side windows, exterior mirrors and windscreen your first concern for the sake of seeing in the rain. Put off the task if the wind is up or the weather is hot and uncooperative, or if rain is in the offing to set you back. Take the time to do a proper job.
You may still be caught by a mozzie or a splash from a road train, but with clean glass it is an easier thing to put up with and the water marks will not become something of a permanent nuisance.
