Quote:
Originally Posted by platt-deutsch
Well, distilled or deionized water will absorb metal ions and deterioration of the metal. That is why metal tubing is almost never used on Reverse Osmosis sytems etc.
Deionized water is exactly that - water that has essentially been stripped of all of its ions. Water likes to be balanced in its natural state, however, and this means that it adds ions to itself to achieve that goal. Therefore, DI water grabs ions from everything it touches that can be dissolved or absorbed. It is about a close as you can get to a Universal Solvent. In your case, it will extract metals from all of the brass fittings you have, and will also pull carbon dioxide from the air - you get the drift.
|
Nice explanation and almost correct. High quality deionized water is almost completely unbuffered and as you say will absorb anything it comes in contact with such as gases in the atmosphere or metals from a container. Most distilled water is made by, well, distillation. Distillation is less efficient since small droplets get entrained in the flow of steam and some minerals are carried over. But still pretty much the same as DI for this discussion.
Reverse-osmosis or RO is different. The water is forced thru a membrane by pressure. The membrane passes a portion of the minerals thru so it is not as pure as deionized or distilled water. In home systems RO typically reduces TDS (total dissolved solids) by about 85% or so. RO water falls into the high quality tap water category so use it if you have it.
On the practical side, assuming you have reasonable quality tap water, you can use it for both diluting coolant and adding to a battery (MB's recommendation). You can use DI water in the coolant because antifreeze is more than just ethylene glycol. It contains corrosion inhibitors which provide the buffering. Using DI water in a battery might make it last a little longer if you measure the battery life with a stopwatch.
But if you are adding water regularly, it's time to check out your charging system.
As for the windshield/headlamp washing system, a high purity water will leave less streaks and less clogging of the lines/nozzles.