[Some_Idiot2]

Tap water IS VERY VERY BAD for waterblocks, and RADs. It has fluoride and chlorine. The tap watter will destroy radiators and heatercores, because of all the junk in it. DO NOT USE TAP WATER, EVER. Only use idstilled water. Trust me, I almost ruined my heatercore by usinging tap water.

 

[Some_Idiot2]

Also, the pipes in my appartment are at least 70 years old, so that may have contributed to all of the corosion that the tap water caused. But you know what you guys know what you are talking about, I guess having in in you loop for >24 hours should be fine.