I lived in a 1 bathroom house until I was 18 with up to 4 other people and I honestly don't remember there being many problems - apart from occasionally having to chip ice out of the bath before getting washed :-)
Same here, though it helped a lot that we were in the middle of nowhere and going outside was very much an option when someone was on the toilet.
Heck, I shared a house with 8 people in college that only had one bathroom... That was more of a challenge, but it was rare that we were all there at the same time, so it mostly worked.
I am not familiar with what this phrase means nor does a quick Google help. Is it to be read literally - "it got so cold during the winter that ice formed in the bathtub and had to be chipped away before use"? Or is it an idiom for an unspecified location.
No - I literally had to chip ice out of the bath some winters.
My parent's house was old and not heated terribly well - which I didn't notice until I went to university and stayed in a centrally heated halls of residence and returned.
