With all of those examples, the actual temperature doesn’t really matter.

For drinking and bathing, people go by feel. In the kitchen, the freezer makes water freeze, and the stovetop will make it boil into steam, but exact temperatures aren’t really relevant here either. The same goes for ironing clothes, the iron just does it.

When I think about where explicit temperatures are needed in the home, the oven and thermostat are the two things that come to mind. Water is pretty irrelevant for both of those. For cooking or frying someone may monitor meat or oil temps, but those aren’t water. A hot tub might have an actual temp on it, but those tend to be around 100F, not 100C, as they are meant for humans, not boiling.

Water is an amazing liquid, but I still struggle to see how measuring all our temperatures based on it makes sense.