I understand distilled water.
Mostly.

De ionized water is a puzzle.

What will deionized water do that distilled water won't?
And what will distilled water do that deionized won't ?

How do you deionized water ?

What are the positive and negative properties of both , please?

Knew a little but not this much, good question since finding distilled h2o at Publix for my CPAP machine has been next to impossible but Purified is there, basically the same thing...

Link Distilled vs Deionized h2o

Deionized and distilled water are two types of water that are used for different needs. While both processes remove impurities, they do so in different ways and to differing degrees, with deionization being the more thoroughly purified version of the two. Learn about the differences and which one best suits your needs here!

What is Deionized Water?

Deionized water, also known as demineralized water, is put through a process called ion exchange. This process removes nearly all ions, except for some trace minerals not present in tap water. Without these ions present, deionized water has excellent purity characteristics and is often used in laboratories or pharmaceutical applications due to its sterility and lack of contamination.

Aside from its use in scientific experiments, deionized water is also commonly used for industrial cleaning. Due to its purity, it doesn’t leave behind any soapy residue or scale build-up and is beneficial for processes that require a high degree of cleanliness. Deionized water can be used to wash parts and equipment and is often used in the food industry due to its non-toxicity. Additionally, because it does not contain hard minerals, it will not cause corrosion of metals like copper pipes.

What is Distilled Water?

Distilled water is produced by condensing steam from boiled water and then collecting the condensation. This process can remove certain bacteria and substances, though it does not typically remove dissolved solids or minerals. Since distilled water has a neutral pH, it’s called “purified” water but not necessarily pure. While distilled water may be filtered to improve taste, it is most pure in its natural state, which makes it safe for consumption and suitable for general uses such as car batteries and irons.

Distilled water is often referred to as deionized water, although the terms are distinct. Deionized water is created through a more in-depth process of filtering and distillation that includes resin and carbon filters to remove, or “deionize”, ions from the other contaminants in the water. The end result of this process is considered significantly purer than ordinary distilled water, with very few dissolved solids. This makes it well suited for industrial use such as cooling systems and medical equipment such as diagnostic machines.

In the pharma industry we deionize the water first (we call that Pure Water). Then we triple distill it. Once it's triple distilled, it's sterile and pure enough to inject into people. This we call Water for Injection (WFI). We use WFI for everything from making solutions to cleaning to adding to drug substance.

Deionized/demineralized water is used to cool most all "high tech" equipment that is water cooled via heat exchanger, such as, nuclear reactors or high power transmitters.

Deionized water is also used in Wire EDM machining. Impurities in normal water would cause many issues.

FWIW, distilled/deionized/degassed water was used to cool the final amplifier tube in the AN/FPS-24 FD radar--a big RCA tube capable of pushing 40KW continuous power. The interesting thing about it was that the water was in direct electrical contact with both the plate and the grid, with a potential difference of several kilovolts. The water had to be incredibly pure to perform that task.

flashguy