[m12k]

Something like this is interesting, but I find it's missing a lot of the info that I care about. For example, here in Denmark, because our underground is chalk instead of rock, our water has high amounts of calcium - this makes the water 'hard', which means we can rinse off soap very easily in the shower, but most of our water-appliances and coffee machines struggle with limescale, and towels need to be washed with a lot of fabric softener or they will come out kinda stiff and scratchy. I'm sure there are other local concerns such as this (e.g. chlorine levels) that would be nice to look up.

[namelosw]

Taking 'hard' water for granted since I was born, it's quite surprising and interesting that water cannot rinse off the soap.

This year I went abroad for a business trip. In the hotel, after washing my hands or taking showers, I found I couldn't rinse off the soap. I was so confused because it was so hard to do it, plus I brought my own soap. I inspected, smelled, and tasted the water carefully and didn't find any difference. In the end, I learned there is such a thing called 'hard' water.

[Delk]

I live in an area of "soft" water. I knew of the concept but I had no idea it affected the rinsing off of soap. I had also never noticed that soap might have rinsed off easier when traveling. (And even if I had, I'd probably just have assumed the soap to be different.)

Conversely, I suppose the buildup of limescale might surprise me if I were to spend time in an area where water is significantly "harder".