Arguing with the chemist who works with water, huh Paul.

Quote Originally Posted by Paul Rust View Post
This is a bit misleading. Although referred to as "deionized" it is actually ion exchange, one ion takes the place of another.

 The exchanged ions never make it out of the resin - otherwise there would be little point in the process.
Quote Originally Posted by Paul Rust View Post
This is true, except that you don't run domestic water straight into the resin tanks and out to the loop. The feed water is Reverse Osmosis so most impurities are already removed. It also goes through an ultraviolet sterilizer to kill bacteria. Lastly it is filtered at the sub-micron level to remove the destroyed bacteria and any endotoxin that may have been released into the water stream.
An R/O-DI system is what you might buy for home use, but in the lab we usually use straight up DI systems that are fed with pre-filtered tap water (2 distinctly different machines/systems). I think it's smarter to not muddy the waters by talking about everything at once though . We're really just getting into semantics.