Would bathing in the clay help eczema?

My friend has a daughter with really bad eczema. They are on a septic system so they don't want to put CDS down the drain. Would having their daughter bathe in the clay help her? And does the clay mess with septic systems?

And I just had another thought. If they were to get a kiddie pool or a big tote, would well water be ok to use CDS in? It comes straight from the ground. So it wouldn't have any chemicals in it.

I use chlorine dioxide tablets in my rainwater tanks and it doesn't negatively affect my septic tank, so no worries about that. 
I would think that bathing in bentonite clay might help. I always say give it a go and see what happens.

Thank you so much for this!