I use whatever Dawn-like soap is on sale. I use sparingly and rinse like a fucking demon. I live in NYC. We’re surrounded by water- and the Catskills Aquifer ain’t running low.
That said, we are heading to an isolated visit to a lake in New Hampshire. We are VERY respectful of the impact that all chemicals have on the septic/ water systems. Bought a bottle of the much-respected 7th Generation Dish Soap. It is quite safe for use where you’re concerned with the impact on local water supplies. Like I will be while at the camp.
I also bought Camping soap for personal bathing. That stuff is so safe that homeowners on the lake use it to bathe with IN the lake.