You are probably right technically speaking. What I meant with "soft"
was a general low level of all minerals, not just calcium.

Be as it may, I just doscovered that something happened to the rear
window defogger switch on the instrument panel while it was in the
shop. Its indicator light is not working, thus I don't know when it's
on and when it's off. The defogger itself seems to work though as I
notice the drying along the heating wires in the rear window when I
press it and the window has condensation, so perhaps its the bulbs in
the switch. The two fuses are OK in the left kick panel. I popped out
the defogger switch from the instrument panel to check on the bulbs
but it has such a short wiring harness that makes it hard to pull out
the switch far enough to even separate it from the connector. Perhaps
some wire got pulled out from the connector while the mechanic was
pulling it out for attaching it to the switch. That would be pretty
bad! I don't know why Honda makes these wiring harnesses such a tight
fit. I might have to remove some of the instrument panel to get to the
back of that darn defogger switch. I know, it's the mechanic's job to
fix it but I don't want to leave the car there for another day if I
can help it.

JP

"soft" means it doesn't calcine, not that it's not loaded with minerals.
 minerals increase the ability of the coolant to electrolyze all the
dissimilar metals in the coolant circuit.

Is it? I also have the official Honda Service Manual and I only see a
strong recommendation for using Honda's own coolant (that is to be
expected, right?) but nothing specific against tap water unless I
missed it. Besides, not all tap water is loaded with minerals. Some
are quite soft.

JP

============================================

Filling the rad isn't enough. There's a reserve bottle that needs to be
filled to MAX, since you've got lots of air in your cooling system. Fill
it to MAX again in a day or two since it will go low as air is displaced
from the heater / block / rad. No tap water. This is in your owner's manual.

'Curly'

This car still runs great with 240 K miles in it but recently I had
some bad episodes which makes me wonder.

The first episode was about a month ago when I was driving at night in
a heavy downpour and I ran into a deep puddle that I could not see in
time. The puddle may have been about axle deep at its deepest point
and the engine suddenly stopped. When the car itself stopped rolling
it was still in the puddle but in only about ankle deep at that point.
Fortunately my electric circuits seemed to be OK as I was able to use
the emergency flashers. As I was ready to phone for some help, I
decided to see if I could start it. Well, the starter seemed to have
plenty of power and after several cranking attempts I was able to
restart the engine and except the initial spongy brakes everything
seemed to be fine.

I still have no idea what caused the engine cutoff: water getting to
the ignition circuits or perhaps into the air intake? I always thought
Honda's electric circuits were pretty well insulated from moisture,
with tight rubber boots, etc.  But maybe somebody has a better insight
into this.

The second episode was about 10 days ago when the normally 30 minute
home commute turned into 4 hours because of a snow storm hitting my
area just at the afternoon commute time. At the end of four hours I
could not even make the last two miles on the side streets so I had to
leave my car overnight at a supermarket parking lot for two days till
the side streets were good enough to drive it home. Later that day I
drove the car on the freeway and I noticed that the temp. guage was
moving really fast to the top that I never noticed before. So I
quickly pulled off at the nearest exit and checked my coolant at a gas
station. Sure enough, the radiator was almost empty as I could pour
about 3 quarts of antifreeze mixture into it. Since then I've been
watching any leaks in the cooling system but could not notice any and
its level has been holding in the radiator after several days. I still
wonder though if I was driving with low coolant level and high engine
temp during some of that long 4 hour commute but I was just not
looking at the guage. The car is still running fine but again it makes
me wonder.

It makes me wonder especially as I noticed the unusually heavy fogging
in my car after the engine warms up and especially when I turn on the
heater.  I get a lot of condensation on the cold windows, even on the
rear window. The condensation does not seem to be pure water but feels
slick like the antifreeze. What is puzzling about it though that I
don't seem to be losing any coolant as far as I can see in its level
visible in the radiator opening. I also see no drips on my garage
floor.  It's a real mistery to me.

I am taking my car to a shop next week but would appreciate  hearing
any insights from those of you having had more experience with cars
than I've had.

Thanks for reading this long post,

JP