Today, we will unpack a lot of information about our RV’s black tank. We can do some things, including best practices, tips, and tricks, to help maintain our black tank effectively. I wanted to dive into this topic thoroughly, so I even put a camera down into the black tank to determine if some myths were real or fake and identify the best practices based on the findings. So that’s what we’re going to be looking at today. Let’s get started.
Let’s address the obvious since this is a given: by now, everybody should know to keep their tanks closed on the RV until it’s time to dump. When dumping, you always empty the black tank first, close it, and then dump the grey tank to clean out the entire system. However, we can take a few steps to get the black tank even cleaner, which I want to focus on here in the beginning.
I will give you three options for rinsing the inside of your black tank. And let me emphasize this—you should be rinsing the inside of your black tank 100%. One of the standout points in that video is just how important it is. He did a fantastic job with that comparison, so it’s a great resource.
The three options we have are:
- The Tank Flush Built Into the RV: This method works well, but there’s a cautionary note to only use it with the valve open. There should be a book written by now on maintaining a quality RV despite the quirks of RV manufacturing, but that’s another topic.
- Using a Flush Elbow: This option has its pitfalls, but I’ll show you how to effectively flush your system using an elbow like this to spray water into your black tank.
- Flushing from Inside the RV is probably the most tedious and time-consuming method. It involves filling your toilet on the inside multiple times and flushing it until you have enough water to rinse out the black tank thoroughly.
To better understand the process, I placed a camera down the toilet to observe what happens during dumping. When we used the onboard tank flush, I wanted to see what was happening inside the tank during the initial emptying process.
off-road trailer
Two things stood out to me from the footage. First, I was surprised to see how turbulent the tank flush system was inside the black tank, which is a welcome discovery. We want that turbulence because it helps in the long run. Second, I could see the bottom after using the tank to flush and drain the system. It wasn’t spotless, but it didn’t have what is often described as pancake batter sitting at the bottom of the tank.
Using a product like Liquefied, our preferred tank treatment for several reasons can help break up the material in the tank, making it easier to remove. While I understand that the black tank is a holding tank, not a septic system, breaking up the waste material is still beneficial for thorough cleaning. I have more to say about tank treatments, but for now, let’s continue discussing the flushing process.
When using the tank flush, we close the black tank valve and fill it up. While the system advises against this, we use it that way and monitor it with a meter. These meters aren’t always 100% accurate, and the information from manufacturers about the black tank’s size can also be inconsistent. That’s why it’s essential to learn your system—fill it slowly, check from the inside, and avoid overflowing it.
It’s crucial to stay in the area while flushing to prevent overflow. It’s easy to start flushing, walk away, get distracted, and return to find the system overflowing through the toilet inside or the vent on the roof. The black tank has a vent on the ceiling so you won’t pressurize the system, but you still don’t want it overflowing. My rule is to always stay in the area during this process.
From my experience, the tank flush creates the most turbulence out of all three methods of filling and flushing. It’s my number one go-to recommendation for cleaning the tank. The second method, using a Flush King or a valve with an elbow that connects to the water, is also effective, though it creates less turbulence. When I observed with the camera, the water rose slowly with minimal movement, starting to swirl slightly but remaining gradual throughout. This method is still beneficial but less dynamic than the tank flush.
The third method, filling the tank via the toilet, is the slowest and longest process but also the safest. Filling the toilet bowl and flushing repeatedly eliminates the risk of overflow.
Also, the myth about liquefied products creating pancake batter at the bottom of the tank is busted. I saw no evidence of that residue when I inspected the tank with the camera. Given that this RV has been used full-time for years, this was a reliable test. I could see the bottom on the first rinse or dump using the tank rinse. While it wasn’t 100% clean, the results were promising.
Finally, I’ll go over how we rinse our tank because, no matter what method you use, you’re essentially flying blind when dumping. You aim to be as thorough as possible, but it’s still a guessing game.
Here’s how I try to achieve the most complete black tank cleaning process after eight years of living in a full-time RV. Before dumping the grey or black tanks, I start by filling the toilet bowl on the inside. Then, I come outside and connect the black tank flush. I open the black tank valve and turn on the black tank flush, letting both systems run simultaneously.
When I see in the clear elbow outside that the pipe isn’t 100% full, I go back inside and flush the toilet bowl, which was already full. This adds a strong gush of water into the tank, working with the turbulence created by the black tank flush to dislodge as much as possible. I prefer to rinse the system twice.
However, I avoid double rinsing if I’m at a location that discourages rinsing at the park or dump station or if there’s a line behind me—I don’t want to hold up others. If I can’t rinse twice, I always reintroduce water to the system to avoid letting it dry. In my opinion, the so-called pancake batter layer at the bottom of the black tank often forms when people dump their tanks, fail to flush them properly and allow the interior to dry out. This creates a hardened layer that’s difficult to remove and can necessitate professional tank cleaning.
To prevent this, be mindful of flushing and reintroducing water into the system. If you can, flush the tank twice. If not, add water afterward. A well-hydrated system is much healthier and easier to maintain.
Moving on, I want to talk more about tank treatments. I discovered some fascinating details that surprised me. Liquefied primarily relies on four enzymes to break down fats, oils, greases, and proteins. I was surprised to learn that it even helps break down hair, which can accumulate over time.
Liquefied also contains bacteria that accelerate the breakdown process. While I understand that the black tank is not a septic system, breaking down these materials reduces the likelihood of clogs and ensures better tank maintenance. Additionally, Liquefied has a built-in surfactant, so there’s no need to choose between a surfactant and a tank treatment—combined into one product.
Let’s continue with the black tank maintenance process, emphasizing the tools and techniques that work well—and some that don’t.
Lubricating Valve Cables
Valve issues often stem from corroded or gunked-up cables rather than valves. To address this:
- Use a lubricant designed for RV slides that don’t attract dirt.
- After emptying the tanks, open and close the valve multiple times to work the lubricant into the cable.
- Be mindful of where you’re doing this—avoid parks with concrete pads where lubricant residue could leave marks.
Proper cable maintenance reduces sticking and prolongs the life of your valve system.
Techniques That Didn’t Work for Us
- Using Ice in the Black Tank
The theory: Adding ice to the tank before driving can break up debris as it sloshes around.
The reality: It requires enormous ice to have any real impact. Ice melts quickly, often turning to water before providing significant cleaning action. While it may help slightly, the effort and cost don’t justify the results.
- Toilet Wand for Tank Cleaning
The wand sprays water inside the tank to clean its walls. However:
- The water pressure is often too low to make a significant difference.
- It doesn’t deliver the “hard-hitting” effect to dislodge debris effectively.
- Dragging a hose inside the RV to use the wand is inconvenient and messy.
For us, these methods weren’t worth the hassle or expense.
Essential Black Tank Maintenance Tips
The black tank doesn’t need to be complicated. Here are a few critical points:
- Use Plenty of Water
- Always flush with a generous amount of water.
- When adding tank treatment, start with a small amount of water to help distribute the treatment evenly.
- Regular Flushing
- Rinse the tank thoroughly after each dump.
- If a second rinse isn’t feasible, always reintroduce water to avoid drying out the tank, which can lead to hardened buildup.
You can maintain a clean, trouble-free black tank system by following these steps and avoiding ineffective methods.
Black Series Maintenance Tips
Maintaining your RV’s black tank doesn’t have to be complicated, and a few essential practices can go a long way toward avoiding clogs and unpleasant surprises.
- Limit Toilet Paper Usage
Excessive toilet paper is one of the leading causes of clogs. Stick to RV-friendly toilet paper and dispose of it sparingly to keep your system running smoothly.
- Flush and Rinse Regularly
Leaving waste in the tank to dry is a recipe for trouble. Buildup can harden over time and become difficult to remove. Regularly flushing and rinsing your black tank, even if you can’t do it twice, will prevent these issues.
- Use Plenty of Water
Always ensure you use a healthy amount of water when flushing the toilet. This helps break down waste and ensures the tank treatment can be distributed effectively.
Perspective from the Field
Understanding the inner workings of a black tank from a live, full-time RVing perspective emphasizes the importance of these practices. Proper maintenance keeps your system clean and reduces stress, allowing you to enjoy RVing fully.
If this guide has been helpful, I hope it makes your RVing experience smoother and more enjoyable.
