I found an abstract testing water in San Francisco.

It says in general SF water is very soft but varies from 6ppm (very soft) to 146 ppm (hard or moderately hard).

The Bosch has a manually adjusted built-in water softener.

You pick the level of softening you want and it stays there.

The Miele (except the Classic) has an automatically adjusting built-in water softener. On a given day where the water is 6 ppm it will test it and do nothing. On a given day that it is 146 ppm it will soften it to the ideal hardness level. And when it runs out of salt the dishwasher will tell you on the information screen.

Here is a link that might be useful: LINK

I live in the SF area as well and part of the year we have reasonably soft water (hetch hetchy) and part of the year when the water supply is from the wells, it is quite hard. We ended up with a whole house softener from Kinetico and turned off the water softener for Miele DW. Soft water basically allows for much better cleaning with the enzymatic cleaners. I find both for DW and laundry, I can use half a tablet or just a TBS of laundry detergent and the end result is much cleaner. I believe products like Limeaway work by acififying the water and making easier for the enzymes to work.