Here's another vote for Costco (Kirkland) TP. We use it all the time in the sticks and bricks and weekend camping. However, when we're spending the winters in Texas we don't have the storage space for those large quantities. We then use the Scott's septic paper and combine it with RV Digest It as a deodorizer/break-down agent. I have a large black tank (62 gal.) and dump it about every two weeks. I monitor the effluent, with one of those clear inserts, when I dump and have noted that I have very few solids in the tank. In particular, the paper has broken down into very small pieces. Hope this helps.