You can wash sheets in a bathtub. You fill the bathtub up to about fifteen centimetres, add soap, add sheets, and then get into the bath and stomp like your father used to do when he discovered that one of the kids had eaten the last biscuit. Then you drain the tub, refill, stomp again. Do that three or four times and you have clean sheets. Generally takes about forty minutes, depending on how dedicated you are. The biggest problem is getting enough water squeezed out of the sheets so you can pick them up and hang them out on the line, because they're bloody heavy when they're soaking wet. Nobody needs a washing machine, and nobody needs a laundromat. They're just really convenient.
That said, washing laundry by hand (or foot) is a bitch and I personally decline to do it unless I'm desperate. I'm not sure Corissia or Juliana are physically capable of standing up long enough to do the laundry stomp, let alone hanging laundry on a line. In my country basements aren't a thing, so the laundry room ends up being at the back of the house, near the clothesline. There are laundromats where I am, but they mainly get used when it's been raining for more than a few days, and no one can use their clotheslines to dry so they need a dryer.
I've spent time in laundromats when I could afford the fee but not the cost of a machine for myself. I've never been in one that isn't manky and dirty. I can't understand why anyone would want to use one when they can afford their own machines.