The "hazards" of deionized water are somewhat blown out of proportion.

Deionized water is not really that corrosive, only marginally more than tap
water...
HOWEVER, deionized water lacks the buffering capacity of tap water.  (All
that water hardness serves to buffer the pH nicely)   So, if the "stuff" you
are rinsing is corrosive inherently, the deionized water also becomes
corrosive, especially to metals.

However, most of the aqueous cleaners are pretty mild and non-corrosive, so
rinsing them with deionized water should be safe, even for the common home
dishwasher.

This is assuming that the ratio of (acidic/corrosive) flux on the parts in
the washer to the amount of alkaline cleaner being used is not so bad that
the wash water becomes acidic...then you have BIG problem.

The answer is to clean just a few boards, OR use a lot of cleaner to keep the
pH above 9, and preferably higher than that...

Rudy Sedlak
RD Chemical Company