I don’t know what the water restriction will be, but you can take a very nice (and thorough) bath/hair wash with a 5 gallon bucket of warm water. Take something like a red Solo cup & wet down hair/body, lather up hair, wash bod with soap or whatever you use, then start rinsing from the top. By the time the hair is totally rinsed, the body pretty much is as well. If there is water left in the bucket (I usually had some), just dump it over your head. Using the bucket, you know exactly how much water you are using. I would fill it up, take out a pot of water & heat on the stove to just boiling, then add the hot water back to the bucket and the temp was perfect for me. My dad and his family took bucket baths when he grew up on a farm .... as a boy, he washed off on the back steps and granddad had a bucket around the side of the house. We are SO spoiled in this day and age in so many ways (electricity & running/hot water come to mind first). For those Libs/Leftists in CA, one would hope this situation would be a teachable moment; however, since Liberalism appears to be a mental disorder, it likely won’t make any difference.
For a video on how to do this see the Kelly Mcgillis bath scene in Witness.