One thing I recently ordered for my preps was galvanized wash tubs and metal washboards. The pictures are links to the ones I bought.
I bought them sight-unseen, beyond what you see in the pictures, but when they arrived I was pleased at how large and sturdy they both were. I bought two of each--although now I'm thinking I should get at least two more washtubs. They will be useful also for washing dishes. They are just very sturdy things.
Once you have those things out of the way, you'll also need a laundry soap to wash your clothes with. Sometimes I make my own homemade laundry detergent, out of Borax, washing soda, and whatever grated bar soap I have on hand. I use cleaned kitty litter buckets to store my homemade laundry detergent. This is the recipe I use for homemade laundry detergent.
Having clean clothes will become a very serious issue--mostly for women (feminine hygiene may be significantly less hygienic) and children (diapers and potty accidents). Right now laundry is kind of more of an annoying chore, but if/when Things Get Bad, it can become a matter of life and death. You don't want to run out of clean pads or clean diapers. And in the case of plagues or sicknesses of whatever type, if someone barfs on you or you're stuck cleaning up after someone who is contagious, you will need both your skin and clothes washed.
Right now I've been focusing more on laundry, but getting a galvanized tub suitable for a bathtub has been on my backburner as something I might consider ordering in the future.
Any of you have laundry-related preps you are up to?