A residential toilet flushes with one to two gallons of water. An RV toilet uses somewhere between one pint and two cups, depending on the system. All of that waste, including the toilet paper, goes directly into a holding tank that typically holds between 20 and 50 gallons. Nothing is being treated in real time. The contents are just stored.
When you flush at home, your toilet paper enters a high-volume system with powerful water flow and eventually reaches a treatment facility or a large septic tank. In your RV, that paper sits in a small, sealed tank with minimal water, sometimes for days or weeks, until you reach a dump station.
That fundamental difference changes everything about what toilet paper can and cannot do in that environment.
RV forums have a colorful name for what happens when the wrong toilet paper meets an RV black water tank with too little water. If paper does not dissolve quickly and waste does not liquefy properly, material piles up under the toilet opening and forms a solid mass that can harden into what experienced RVers call the pyramid of doom.
At that point, no amount of tank treatment chemistry fixes the problem. The tank has to be manually cleaned, which involves either a high-pressure flush wand or, in serious cases, a tank cleaning service. It is expensive, inconvenient, and completely preventable with the right toilet paper and enough flushing water.
RV holding tanks use sensors to show fill level. These sensors are probes that extend into the tank wall at different heights. When waste or undissolved paper sticks to those probes, the sensor reads as full even when it is not. Conversely, a sensor fouled at the wrong position can give false empty readings.
Experienced RVers know not to trust their black water sensors after a while, which is genuinely inconvenient. The fundamental cause is toilet paper and waste accumulation on the sensor probes. Paper that dissolves quickly and biodegrades fully stops accumulating on those sensors. Your gauges stay accurate. You actually know what is in your tank.