Diluting coolant and water

I bought 10 litres of de-ionised water for mixing with coolant the other day and was asked why I don't use tap water. I had to reply by saying that this is just something I have always done as it used to be said that tap water contains impurities causing issues within the cooling system..
Anyone else using de-ionised water?

I do now (not in my MG, in my other car - I don't really care at this point as its cooling system is all getting ripped out next year anyway with the engine) but didn't when I lived in a very soft-water area.

I'm an ex lithographic printer and the water we have here in the North West of England is one of the softest and chemically pure in the country.
I always use tap water in my coolant mix and am happy do so.
I'm sure that de-inonised would perhaps be better if you live in the South of the country and indeed it was always recommended at our sister print companies down there.
It probably is better than tap water but not enough for me to use it.

Here in Melbourne Australia the tap water is excellent, but in some other parts of the country like Adelaide the tap water is quite hard, in such places distilled water or tank water should be considered.

That makes sense, the harder the water the more impurities hence the limescale build up of kettles and dishwashers in some parts of the country. I will continue with de-ionised for now, but I think the water I use is relatively soft as I don't have any problems with limescale.etc

Liverpool water super clean My home city Nottingham Limescale very bad .

Fiddler wrote: Liverpool water super clean My home city Nottingham Limescale very bad .

That's because Liverpool water comes from Wales :whistle: :whistle: :whistle: :whistle: