Originally Posted by dhanna6powerstroke
Depending on how they flush it. Some guys do the initial flushes with tap water and the last flush with distilled before filling with coolant. When i did mine, I used all distilled water and went through 40-50 gallons
I did that also. Granted it has pure distilled water in it without any trace of tap... I dont think I would do that again if given the chance. It was a lot more water than i expected in order to get a clean flush. I think i had 60 gallons used once it was all said and done. I think using tap water untill you get a clean flush is the way to go... then flush several times with distilled to clean out the minerals, ect from the tap.
To answer your question about how many gallons of distilled to provide...
the coolant system holds 27 quarts (almost 7 gallons) 3.5 gallons of concentrated coolant and 3.5 gallons of distilled water. But take in consideration what has been mentioned about the flush itself, and that part is up to you. If your paying someone to do it for you, then talk to them prior to droping it off and see how they are going to do it (or how you want them to do it) and then decide how much water to buy