How to eliminate a ‘poop pyramid’ and prevent one from forming

Tony FlammiaRV Tech Tips

It’s a very common problem in the RV lifestyle, especially with new RV owners. People hook up a septic hose to their RV and attach the other end to an outlet at their campsite. Then, they open valves to both the black and gray water tanks to flush all the yuckiness down the drain. 

But, they forget to close the valve to the black tank. When they flush the toilet, all the water drains out, but the stinky stuff remains. They soon create a dreaded “poop pyramid” of solids expelled from our bodies and fats coming from the sink. 

The solids dry up and accumulate into a rock-hard pyramid that eventually clogs the tank so nothing can get out. It also creates a rather stinky situation inside the RV. 

Fortunately, there are some easy fixes to correct the problem, said Todd Henson, the lead technical instructor at the National RV Training Academy. 

Understand tank management

It’s fine to connect the sewer to a campground outlet as soon as you arrive to a site, but do not open either of the valves until the black water tank is three-quarters full or you’re about the leave the campground. 

If you have a lot of people taking showers in the RV, it is okay to leave the valve to the gray water tank open. But, ideally, you still need some water inside the gray tank. So, keep that valve closed and let water accumulate. 

“When using the toilet, many times we just flush the contents until we can’t see it any more without adding sufficient water to help break down the solids,” said Todd.

There are two ways to ensure there is enough water in the black tank. First, let the toilet flush for an extra five seconds each time it is used. That will ensure there is enough water in the tank to turn solids into sludge. 

Second, hook up a garden hose – NOT YOUR DRINKING WATER HOSE – to the black tank flush connector and add some water to the black tank. But, don’t flush the tank until it is three-quarters full. 

When it is time to dump the tanks, empty the black tank first and let all the contents flow out. Then open the value to the gray water tank so the contents can rush through the stinky slinky and flush out any solids trapped in the coils. 

“It’s a good idea to attach a clear elbow to both ends of the septic hose. This allows you to see the color of water coming out of each tank and out of the hose,” Todd explained. “You know the tanks have been properly flushed when water is clear at both ends.”

If the water is still dark or murky, then close both valves and fill the tanks again by adding water to the black tank through the flush connector, and by running the shower and sinks for a few minutes to add water to the gray tank. 

Warning: When using a flush hose to add water to the black tank, you’ll want to carefully flush the toilet several times during the process. When adding water to the tank, there is nowhere for air inside to escape. When the toilet is flushed, it releases pressure that can create an explosive volcano inside the bathroom. 

Add bacteria

The RV industry has a number of products that advertise an ability to control odors and break down black tank waste. Many products use scented chemicals to do the job. That’s not good for campgrounds because the chemicals kill bacteria needed to break down solids in a septic system. 

Todd recommends Unique RV Digest-It. It comes in a white bottle with green lettering. The product is a combination of bacteria and enzymes that naturally break down solids in the holding tanks and, when flushed into the campground’s septic system, continue doing their job to break down solids.

To test the product, Todd put a cup of dry dog food into each of two sealable baggies. He added a capful of Digest-It to one baggy and a heaping scoop of what he called “blue product” to the other. Then he poured in enough water to cover the dog food and let it sit.

Within two hours, the Unique Digest-It had transformed the dog food into slimy sludge, but the blue product still had big chunks of dog food mixed with water. 

So, if you accidentally create a poop pyramid, you can eliminate it in less than two hours with a capful of Unique Digest-It, adding water to the tank and letting it sit. The tank’s contents should flush out a few hours later. 

If you want to learn how to fix the majority of problems you’ll encounter on your rig, check out the programs offered by the National RV Training Academy. You can even find information about becoming a certified RV technician or inspector by visiting