Alright this topic bothered me so I figured the onus was on me and looked it up. Apparently cold tap water temperatures in some cities around the world are usually around 15°C and can go as high as 25°C in summer. That's definitely not my experience, I'm pretty sure it's constantly below 15°C here. So then you're not a crazy maniac and the regional differences really are way bigger than I expected. Who would've thought!