wrote in message
om...
some last-minute discoveries:

1) the white powder does not fizz in vinegar - but it IS further
crushable to a fine white dust...

2) it does NOT taste like salt.

3) it has a dirty white appearance in the vinegar - like a white/brown

i should also point out that i live over an aquifer-fed water supply
in South Central Texas - the Edwards Aquifer.

historically, we have had heavy limestone deposits in our water
supply, but i've seen and drank the hard water, and this is NOTHING
like that...

my suspicions still lie with the plastic dip tube, except that large
white SOLID marble-sized pieces came out of the water heater when i
drained it 2 weeks ago - they looked like crystalline
formations...like "jacks" of yore...

Hmmm. Your new information changes things. If the problem is a
deteriorated dip tube, the bits will be somewhat soft. The chips that I
found in my faucet screens mushed into a white, somewhat pasty, mass.

Since it's a relatively new tank, I wonder if some kind of cleaner or other
material could have been left in the tank during manufacture. Maybe it's
time find out what that stuff is. Take some to a local lab or even to the
local chemistry teacher and run a few basic tests. You probably don't
drink the water from the hot water tap, but there's always the chance of a
harmful chemical.

TKM