Out here in the states, distilled water is cheap and readily available - especially at refueling stations for that specific purpose.
Wow. Can I have a source on that? Normally water pumped to consumers thru pipes are chlorined in the EU to avoid germ growth - also with a lowered ph to avoid deposits. And for coolants glycol is naturally added only to avoid freezing since we can have -20° winter days up here in the nordics. Dealer and interweb told me G13 is recommended for any Prius since gen2..
Source is my neighbor via me. He is a retired chemistry prof who told me years ago that our tap water is so soft they use it as distilled water in their lab. It does have chlorine as you can sometimes smell it. But the beauty of chlorine is you just set the water out for a time and it evaporates away. We do have naturally occurring flouride so it isn't perfect.
Distilled water is defined as pure water molecules. It’s not up to your neighbor to redefine Any contaminants including chlorine or fluoride makes it by defintion not distilled. These are the other molecules or elements that will get stuck in filters or in the case of coolants, the block. It’s the boring truth of chemistry. Distilled water - Wikipedia
My neighbor is "Defining Man" and if he says it I believe it. He's more reliable than Google AI when it comes to chemistry. should have been there for our talks on alcohol . . . Wild! Ya, I'm sure there's some fluoride molecules here and there but coolant passages are huge.
That tap water might be very close to distilled water when it arrives at the city's water system, but it will be significantly chlorinated when it goes out in the pipes. Note that neither of the two MSDS links which were posted earlier list any chlorine or chlorinated compounds. The Prestone did have some sodium in it. The Toyota coolant is essentially just ethylene glycol, a little water, something to make it taste terrible, some pink dye, and a small amount of mystery ingredients. The Prestone looks pretty similar to Toyota's brew, but with the glycol component(s) diluted by 1/2 or so.
High voltage, non-conductive? At first I thought that this might be an AI hallucination but apparently it really is a thing for EV coolants. Seems unlikely that anybody is actually running coolant over charged HV conductors but as a safety measure, in case of a leak, it makes sense. Electrical Conductivity in Vehicle Coolants In short, the manufacturer tries to eliminate ions from the coolant so that it has a much higher resistance than typical coolants. (Because fewer charge carriers. Pure water has a very high resistance but conducts well once it picks up some ions.) That is out of the bottle. After it has been in the car long enough it might pick up enough metals and such to achieve a conductance considered too high for safety in an EV. Which suggests another factor determining "when to change the coolant" in an EV. Pretty sure none of the existing test strips have a measurement for "conductance" though. And the limits discussed in the link above are so low it doesn't seem likely that just sticking the tips of both ohmmeter probes into the coolant would be able to get an accurate measurement. Which is not the same thing as the corrosion test using a DC measurement between the coolant and ground: