A lot of detailers recommend using a "Di vessel" to de-ionise your tap water (
https://www.amazon.co.uk/Pressure-Re...NsaWNrPXRydWU= )
They connect to your hose or pressure washer and supposedly eliminate water spots entirely, meaning the car can be left to dry on its own if necessary. Never tried one myself, but I've often thought about it
Cliff