Sorry, just had to say my piece . . .

Even biodegradable soap harms waterways. You should take water from the
stream, lake, etc and wash (with biodegradable soap) some distance from the
water.

Read the label on the soap - it will probably say something along the line
of "will breakdown within 2 weeks" - ie it does still polute, the effects
just don't last as long.

We've recently finished a two month trip in our westy (and have done this
several times before). We sponge bathe in the westy most of the time, but
always look out for truck stops, public swimming pools, marinas etc. Some
campgrounds/RV parks charge their customers extra for showers (I can't get
over this!) - often they are happy to "sell" you just a shower.

> take a bath in a creek or pond.   just use biodegradeable soap.