Coolant, tap water, de-ionized water or distilled water?

[Noesph]

As title. Is a tap water, coolant 50/50 mix (Glysantin G33 - psa 9735.k4) ok. Or is putting distilled water (or de-ionized), coolant 50/50 mix in over the top. My thinking is the water is pretty hard around here (going by my kettle).

Being a wet liner engine I want to try and avoid galvanic corrosion with the steel liners and ally block, and I don't want all its insides getting all scaled up like an old kettle.

So pretty much, which water the best for mixing with coolant?

[Noesph]

Not getting through any. Next weekend I'm changing the cam belt and water pump, it needs to be drained to change the pump, so I thought I might as well put new coolant in as well.

[Noesph]

It does make sense, anyway I'm going for tap water.

I found this, after a fair bit of searching.

http://www.coler.de/col/sicherheitsdatenblaetter/b...

Water hardness 0 to 20 dGH (0 to 3.6 mmol/l)

and these (as I'm on the border line)

http://www.waterplc.com/waterquality/L21.pdf

Hardness 1.94 (millimol/l)

http://www.waterplc.com/waterquality/L19.pdf

Hardness 2.33 (millimol/l)

So, the tap water in the area is within there limits.