Dove soap is environmentally friendly and the soap breaks down in the septic tanks and sewer systems pretty easily.
Dove Bar Soap contains minimal packaging so that also makes it more environmentally friendly than soap that is in jugs or plastic containers.
All soap will eventually filter through the earth once it gets out in the earth but when you live in a city or town with city sewer the sewage treatment plant takes the sewage through a treatment process that breaks the sewage and soap down.
Then the water is returned back to the lakes, streams or just into the earth.
I have a septic tank and use Dove Soap for washing hands and for showering and my septic tank works just great.