Yep, over on the Pommy forum lots of them use water purifier/softener systems to (amongst other things) prevent water spotting on the car.
It's all about the level of dissolved salts and minerals in your tap water.
At my joint the only exterior tap is recycled water which has an absolutely mahoosive amount of minerals in it (waaay too much for any water softener to cope with) and if I use it on the car the water spotting is horrendous and takes literally hours to remove.
So I have never washed the F-Type using this water, instead 95% of the time I use waterless wash in the garage (Dodo Juice Basics of Bling Quick Detailer, fantastic stuff!) and the other 5% of the time I go down the car wash and use only two things - high pressure soap and spotless rinse (so zero touching of the paintwork) then back home a quick going over with the Dodo Juice.

 

All of the water in our house and external taps goes through filters (a pre-fliter then an aquasana rhino filter) to remove most impurities, I tested it recently (to see if it would affect fish in pot ponds) and it has zero chlorine in it and neutral ph, whereas my neighbour's registered for both.

I dont think though that it completely prevents water spotting as in my experience this occurs when dust settles in the water droplets and then that creates water marks. That said, a blast up and down the highway removes 90% of the water from the car after a wash, with only bits around the rear bumper and license plate remaining to be wiped off with a microfibre cloth. I am still frothing over how good the polish angel products are, they have really made looking after our cars a breeze.

 

Had a filter/softener system installed in my house when we bought it last year. Guy asked if I wanted to exclude the outside taps to save on salt. My first thought was hell no, need that soft water for the cars more than for my shower.

 

It should be noted for those that are unaware that there is a difference between demineralization and water softeners.
I will leave the science for google to explain properly but most water softeners leave a small amount of salt in the water, demineralization leaves nothing in the water.

 

That's not so much a blog post as it is a clickbait spam ad for products. You have one post and your location is Pakistan?

 

Mods: thanks for removing the offending post. Feel free to remove this one and my quoted one as well.

 

I thought you wanted deionized (DI) water to prevent spotting?
At least some car washes around here advertise that to prevent water spotting.
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