Re: 954 Proper coolant Flush and fill process.
Normally you don't want tap water in your system due to the minerals. If you live in a hard water area, you really don't want tap water in there. When you mix coolant and water, you use distilled water.
If you are looking at replacing the coolant. Mix some extra, drain the current, leave the system open and pour some in, the new will help push some of the old out. Button the system back up and then fill, burp, fill, burp, etc. until all of the air is out.
Alternatively, if you don't want to pour new coolant in to help flush the old out, just pour some distilled water in.