I’m optimistic You’ll have no idea what this is. Try to prove me wrong if you can.

Hand washing entails soaking, pounding, scrubbing, and rinsing soiled fabrics.

Before indoor plumbing, all of the water required for washing, boiling, and rinsing laundry had to be carried from a pump, well, or spring.

Hand-carried water would be heated over a fire for washing and poured into a tub for laundry.

This meant that the amount of warm, soapy water available would be restricted; it would be reused, first to wash the least filthy garments, then to wash increasingly dirtier laundry.