Well, I suppose the general rules are along these lines:

Dig a small hole at least 100ft from any water source (lake, river, stream, etc).

Boil water to wash and rinse your cookware.

Wash your cookware with bio-degradable soap and water and pour the dirty water and rinse water in the hole.

Fill the hole and cover it with the natural debris in the area, leaves, twigs, dirt etc. The goal is to make it look like it never happened.

Personally, I almost never boil the water I use to clean my stuff, we have good water here. I don't use much dish soap either. Sometimes I don't even bring any at all. I carry a couple lightweight washcloths and a piece of a scruff pad to clean and wipe the stuff off when I'm done eating and then I lay them out to them dry overnight.