Your RV’s black water tank is the tank under your rig that holds the wastewater from your toilet. While where everything goes when you “go” is no one’s favorite thing to think about, it makes RVing so much more enjoyable than tent camping. You have an option other than pit toilets at the campground.
We’ll take a look at your RV’s black water tank – what it is, how to clean it, and how to keep it in good working condition.
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1. What is an RV Black Water Tank?
The black water tank is one of two waste tanks – a gray water tank and a black water tank – on board an RV.
The black water tank collects wastewater from your RV toilet, while the gray water tank collects water from RV showers and sinks. The soap residue and dirt can give the water a grayish look.
Your black water tank allows you to use your RV toilet without always needing to be hooked up to a sewer connection. When your tanks start to get full, you can dump them into a city sewer at a dump station.
The black water tank collects both liquid and solid waste, so caring for it is a bit different than your gray tank. In addition to human waste, the RV black tank also collects water used to flush the toilet, and of course, toilet paper. This is why it’s important to use RV-specific toilet paper with your system – it’s more easily degradable and less likely to clog your rig’s sensitive plumbing system!
2. How do I Clean my RV Black Water Tank?
One of the most important things to know about your RV black water tank is how to keep it clean and odor-free. There are several commercial chemicals and deodorizers that make it easy to treat and clean your black water tank.
At the start of your camping trip, add a does of RV black water tank treatment. These treatments can come in liquid form, like Aqua-Kem, or in pods that you drop in the toilet and flush. Be sure to add in about a gallon of water, as well, which helps the chemicals do their job.
Along with keeping tank odors down, these chemicals break down solid waste and toilet paper. That makes a smoother process when it comes time to dump your tanks.
In addition to maintaining your black water tank with these cleaning solutions, it’s also important to deep clean your tanks on a regular basis. A good time to do this is between camping trips, or before putting the rig into storage.
The materials used for a deep clean vary among RV owners, but the method is the same. Drain your waste tank completely before filling it ¾ full with fresh water and a small amount of bleach, Pine-sol, or laundry soap. Then, drain the tank, before filling it ¾ full again with fresh water. Repeat this last step until the water runs clear.
3. How Often Should You Dump and Empty Your Black Water Tank?
The frequency with which you need to dump and empty your tanks will vary depending on the number of people using your RV, how often you’re at camp, and several other factors.
Most self-contained RVs have a sensor that tells you how full each of the tanks is. This includes the black water tank as well as the gray water and potable water holding tanks. However, some smaller trailers don’t have a sensor. With those trailers, you have to figure out when to empty tanks as the water level rises.
At the very least, you should dump and empty your black water tank after each camping trip, or every 3-5 days during a trip. It’s important to empty your tanks at the end of a trip, because you don’t want to store your RV with wastewater in the tanks. In fact, you’ll want to thoroughly flush your system to clean it out before storing your rig.
4. How do I Dump Wastewater from my Black Water Tank?
To dump your RV’s black water holding tank:
- Begin by pulling on a pair of rubber gloves for protection.
- Hook up one end of your sewage drain hose to the black tank valve on your RV. Secure the other end of the hose to the valve at the sewer line or dumping station.
- Pull the valve to empty the black tank, allowing it to drain completely.
- Flush the black tank with water to clean it. Depending on your setup, you may be able to do this using the water from your gray water tank.
- Drain all of the water from the tank.
- Repeat steps 2-4 with the gray water tank.
- Close the valve and remove the hose from your RV water tank.
- Rinse off the inside of the hose before disconnecting from the sewer connection or dumping station.
- Remove the sewer hose and properly store it.
5. What is RV Black Tank Flushing?
Some RVs have a built-in RV black tank flush system. This allows you to connect a hose directly to an inlet valve to essentially power wash your tank.
When using the flush valve, you’ll want to follow your manufacturer’s instructions to ensure you’re using it correctly. Most guides suggest you leave the black tank valve open so that water doesn’t back up and end up flooding your RV through the toilet!
If your RV doesn’t come with a built-in black tank flush system, it is possible to install one aftermarket. This type of after-market option comes in many shapes and sizes. Some can be attached to the dump pipe, while others require drilling a hole in your RV’s black water tank.
If you don’t have a manufacturer’s tank flush valve, and you don’t want to add one to your tank yourself, you will need to clean your RV black water tank manually.
One option is to use a garden hose extension called an RV holding tank rinser that goes down the toilet. This rinser is designed to spray water in multiple directions in order to clean debris and tissue from the sides of your RV black water tank.
6. Portable RV Waste Tanks
If you camp in the same spot for long periods of time without sewer hookups, you may need a portable RV waste tank.
These allow you to empty the contents of your black and grey water tanks into an external tank, which you can then transport to a dump station. RV portable waste tanks usually have wheels and a handle, so they can easily be pulled across the campground for dumping.
If you use a portable RV waste tank, you should take the same care to clean and flush it as you do with an onboard RV black water tank.
Frequently Asked Questions about RV Black Water Tanks!
Here are some of the most common questions people have about their RV black water tanks.
What’s the difference between gray water and black water?
Gray water is the wastewater that comes from your sink taps and shower — whereas black water is the wastewater that comes from your toilet. See our guide on RV water tanks and RV holding tanks for more.
How accurate are the black tank monitors?
The accuracy of your tank monitors depends on how often you clean them! Keeping the sensors on your monitors clean will ensure they give an accurate reading.
What are the best practices for black tank dumping?
Ensure you’re dumping your holding tanks into a city sewer connection made specifically for that purpose. Do not dump tanks onto the ground or into a street sewer like Cousin Eddie in Christmas Vacation!
It’s also a good idea to keep your valves shut and wait until the tanks are full, or nearly full, to dump. You’ll have the help of gravity and a lot of water to wash the icky stuff through the hose.
Keeping tanks closed until full also helps prevent clogs. Without water constantly sitting at the base of the tank, your waste’s odor will be more pungent. Some water in the tank will also prevent anything from sticking to the bottom of your tank, which makes it more difficult to remove.
What are some black tank maintenance tips?
Always use specially formulated RV holding tank chemicals to ensure your tanks stay odor-free, and that waste is broken down quickly and effectively. While you can use mild dish detergent or ice to clean your tanks more thoroughly, avoid using harsher substances, like antifreeze, which can dry out the seals and ruin your sewer system.
Does my toilet use affect anything?
Your RV toilet isn’t like the one you have in your home. Flushing trash, feminine products, and traditional toilet paper can lead to a clog. Treat your toilet with care and only flush the bare necessities.
Do I have to dump my own black tank?
An increasing number of campgrounds are now offering “honey wagon service.” Someone will come around in a truck with a large tank and will dump your tanks for you, typically for a fee. Many KOA campgrounds now offer this service to guests as another perk.
Dealing with your RV black water tank is definitely one of the more unpleasant parts of using an RV. However, the comfort and privacy that having an RV toilet on board affords you and your family is one of the biggest advantages of having an RV. Understanding your RV black water tank, and how to clean it, will give you years of comfort and enjoyment.
If you want to learn even more about your RV’s black water tank and about maintaining and repairing your RV in general, check out NRVTA’s program. Use code RVSHARE for 5% off all courses.
