Will my engine rust?
Context: I bought a 2000 Jeep Grand Cherokee not too long ago, it has the 4.0 I6 engine. Today I did a water pump and thermostat, while I had the cooling system apart I flushed it out with hose water earlier in the day. For a variety of reasons the job went later than expected and I ended up getting to the end of the job by almost midnight due to concerns of flash rusting since the block is cast iron.
While I was getting to the last hose my flashlight slipped and knocked the hose out of my hand, heard several metallic dings and realized that my car just straight up ate the hose clamp, spent 40 minutes looking for it in pitch black darkness with a crappy flashlight to no avail. As I'm typing this its 1:21 AM in my local time so it's far too late to run out and buy a replacement. Ended up just buttoning up what I could and called it quits for the night
Now my concern is corrosion due to tap water lacking the necessary anti corrosive qualitites of anti freeze. So I asked google if anything bad would happen if I left tap water sitting in an engine overnight, some posts said "Hose water is fine to use in an emergency and can be driven on for a short while, should be changed soonish" others posts said "No, tap water bad, can be used to flush, but get that junk out asap."
Did I just put my engine on death row, or is it really not that bad?