I use 50/50 mix with regular tap water. Never had issues with my vehicles. At $250 for the entire cooling system it's not that huge of an issue. You should replace most of the parts in a time frame of 3 years anyways. At least with the amount of miles mine get.

 

I suppose a lot of it depends on what your tap water is like. I installed a whole-house filter here because of all the lime and such.

 

This is how I've always done it too.

 

I just removed he top heater hose and the top radiator hose from the t-stat housing and stuck my hose onto the heater hose nipple and flushed it for 15 minutes. The water comes out of both the top radiator hose and heater hose. Then I flushed the heater core by it's self and then forced as much water as possible out of the system with a compressor.

 

My system was relatively clean to begin with though, only a little bit of junk came out and my coolant was still good and green when I did it.

 

Any clean drinkable water properly mixed with coolant is fine. The Prestone jug says nothing about must/should use distilled water.

 

At less than one dollar per gallon I will stick to distilled water.

Its obviously not gonna hurt, and I gotta go to the grocery store for beer anyway...

 

I agree, just saying distilled water is not mandatory/required but certainly acceptable, maybe even preferable.

 

WOW that is alot of ways to flush, I did mine with just the plastic plug out of radiator. But put a 5 gal bucket under it and water hose on the top.
I started it up got it hot and let it drain, After i looked clear i turned on the heater and you can see it go dirty untill that cleared. Kept an eye on temp and never went over 215. That was a year ago and it still looked nice green. Just did it again few weeks ago and put some of my 2007 wrangler mix in it has a higher temp for new cars.