Originally Posted by blueoval
Yes that is a good point, I usually wash my car late in the arvo or early morning to avoid the heat of the day and watermarks burning into your clearcoat. Tap water is really bad for cleaning you car with because of the chemicals in the water, when that water dries, its almost acidic to the point that not even buffing can get water stains out from your duco.
WHEN WASHING YOUR CAR, CHAMOIS DRY IMMEDIATELY AFTER!!!
Don't know where you live but if any drinking water were acidic, ph<7,(or alkaline, pH>7, for that matter) it would burn in your throat/stomach a hole only a surgeon could fix (slight exageration). Drinkable tap water will not harm your paintwork, but rather a grimey sponge, detergents that are harsh (often alkaline to aid grease removal based upon the original formulated requirement) lazy/el-cheapo detailers that do not use good quality buffing pads, using cutting compounds on new paintwork etc...A raw material suppliers guide I have stresses not to polish a new car using any product with abrasive components due to the damage on clear coats. It recommends using neutral detergents or car shampoos, waxing only, with a soft, non-abrasive wax-based product, washing out of direct sunlight or on hot bodywork, wetting quickly to remove any obvious larger solids and then washing and rinsing in small areas roughly as large as your arm spans to avoid detergent spotting, which a higher quality product will be designed to avoid and chamois drying (although I like the quick-spin-round-the-block method to "air dry" and dry out the brakes.
edit: just checked that you're based in Adelaide, blueoval, where your water is "harder" than most places except Qld. Melbourne and Tasmania have the softest water (low iron & mineral levels) and highest quality. If the same detergent was used in both QLD and Vic on the same identical soiled surface it would foam higher and clean better in Vic due to the softer water, hence a "good" chemical company would adjust their formulation for Qld destined products to add more water sequesterants and assist in boosting the cleaning properties...end of Industrial Chemistry 101, class dismissed...