I'm in Fountain Valley. I called the local water people and they said it's okay so as long as I use a hose attachment. My landlady said "NO" so I listened to her. (BTW, what did the letter you received say?)
Anyway, what I do is surely similar to these others. I use a small 2 gal bucket from home depot. A gallon of distilled water. ONR. I pour a little of the gallon of distilled water into the bucket. Pour in my ONR into the gallon of water, NOT into the bucket. Shake it up well. I use as many as MF towels as needed, starting with about four. I pour from the gallon of distilled water/ONR mix into the bucket, just enough to saturate the towels and a little more. I pour more into a spray bottle (I use a Kwazar) that I use to pre-soak the panels before hitting them with the MF towels. I save whatever is left of the gallon of distilled water/ONR for future use. Money saved
I do one panel at a time. Spray. Let it sit a bit. Wipe. Wipe. Dry. Repeat. I inspect the towel after each wipe. The second wipe, usually another side of a folded-in-fours towel, is to make sure I got all the dirt off the panel.
I use separate waffle weave towels to dry.
Here is a pic of a car that is about as dirty as I would consider for rinseless. I do this one fairly regularly and the owner is always happy when I'm done.