How often should I empty my RV’s black holding tank?

Living with a black holding tank is one of the less thrilling aspects of a long RV adventure. But caring for your black holding tank will help you avoid common issues like persistent odors, clogs, and false sensor readings. One of the most important things to know about your holding tank is when to empty it (although knowing where to empty it is also handy).

More frequent emptying is not necessarily better, and will actually probably worsen your holding tank issues. If you dump the tank often or keep it hooked up to the campground’s sewer system, the liquid waste will drain out, but the solids will remain. That’s how you end up with residual waste caked to your tank’s sides, interfering with sensor readings.

Instead, wait until your holding tank is about 2/3 of the way full so that when you dump it, there’s adequate flow. With two people living in the RV, that shouldn’t be less than one week, but keep an eye on your sensors.

If you have a grey holding tank that also needs to be emptied, dump the black before the grey. The greywater, which comes from your sink and shower, will flush out any remaining solids in your hose.

After a while, you might notice your sensors not reading as well as they used to, or a residual odor emitting from your black tank. When this happens, you can always use a packet of deodorizer to deep clean everything. Commando contains powerful enzymes that break down solids and digest odor-causing bacteria. Just drop in a packet, add water, and wait about 12 hours. Your tank will be good as new.