(ET) Distilled water

[John Darwin Powers <jdp3 cornell edu>]

By definition, distilled should imply using a "still" to process water. 
 In some cases, contaminated water can continue to be contaminated even 
after distilling if the contaminants have the right volatility.  For 
most water this will not be a problem.  Technically, you could use 
water from a dehumidifier, as the water is recovered in the second 
process of distilling, but I would never use the stuff for a battery.  
Remember, the condenser coils are usually aluminum, and can react with 
other things, and because it is a rather cool process, it will not kill 
anything that can grow.  Never keep distilled water in a metal 
container.  Cleaning agents including baking soda should never be used 
to clean a battery.  Well, elbow grease is the only acceptable stuff 
that you can use.  Another way to produce distilled water is to use a 
resin base.  This is chemical distilling, and is used in laboratories 
to produce water with a specific ion content ... essentially 
"polishing" the water.  The funny thing is that you can actually 
"over-polish" the water and make it corrosive, as it will "scour" the 
materials it comes in contact with to make-up its ionic balance.