Can you polish glass?

[mrgmhale]

That's too much work to clean the water spots on my shower doors (due to really really hard water).

For our houses I have hade over the past 30 years I ended up handling the hard water, and water spots by installing a commercial quality water softener to treat all household water. For a few of the houses I did not bother with the water fro the lawn sprinklers. But, for the outdoor hoses I did re-route the piping to provide soft water to the spigots. In other houses I simply provide soft water everywhere, as there is no separate plumbing for lawn sprinklers (current house in Rochester, NY - plenty of rain for the lawn falls naturally). We then use a 5 stage Reversed Osmosis filtering system to get purified water into the kitchen and master bathroom.

The softened water has not eliminated water spots. But now whatever spots we get a "soft water spots," from non-mineral content dissolved in the softened water. The main house filter (pre-softener) removes items larger than 20 microns in size, plenty good for household water, but it can allow some dissolved "soft" items to remain. For our drinking, cooking, toothbrushing, the RO filtered water is filtered down to 0.0005 micron - but it is not practical to filter enough of that ultra-filtered water for washing or rinsing the car off. Soft water spots are very easy to deal with, and a chamois or micro-fiber drying is more than sufficient to get a nice shine with no spots that appear.