For the fastest and most complete breakdown of toilet paper in the septic tank, single-ply toilet paper is best. Regular toilet paper is acceptable as well; there is no evidence that any type of toilet paper harms septic tanks or drainfields.
Toilet paper advertised as being thicker and softer takes a longer time to decompose in the septic tank, which may mean more frequent pumping of the tank. InspectAPedia recommends that people with septic tanks use recycled toilet paper, as it is a more environmentally friendly option. Trees do not have to be cut down to manufacture recycled toilet paper, and less chlorine-based bleach is used in its production, which decreases groundwater pollution.