The black water tank tends to be one of the most intimidating aspects of RVing. Check out these hacks to simplify and clean up the process (pun intended).

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RVing allows you to explore the world at your own pace. You aren’t confined by needing to stop and check in because it’s bedtime. Nor do you need to worry about stopping for food or “pitstops”. But, therein lies the concern for many. And the black water tank often keeps people from jumping into the adventure and independence that is RVing.

What is the Black Water Tank?

An RV has three separate water tanks: fresh, grey, and black.

The freshwater tank is just that. It’s filled with fresh potable water. This is where the water comes from when you turn on your sink faucet (kitchen or bathroom), run your shower, or flush your toilet. It is filled from your regular city water supply.

The grey water tank holds your non-sewer wastewater. Basically, anything that goes down a drain–sink, shower, dishwasher, washing machine, etc. It’s not really dirty, but it’s not really fresh anymore either.

The black water tank is where all your sewer waste is held. Meaning, every time the toilet is flushed, this is where it goes. While the fresh and grey tanks do require some basic maintenance, the black water tank requires proper care to ensure there is no odor backup. But nothing too complicated or onerous. (Yes, I know. Rhymes with odorous…)

So, let’s go through some basic maintenance, helpful accessories, and flushing tips.

Regular Maintenance

Regular maintenance is vital in preventing issues with your RV black water tank. Here are some basic maintenance tips:

Use RV-Specific Toilet Paper: You will need to use RV/Marine safe toilet paper. Regular toilet paper will clump and clog the tank. Biodegradable RV toilet paper will break down more easily.
Practice Proper Flushing: This refers to two separate aspects of flushing–macro and micro. In a macro sense, every time you empty the black water tank, you should flush it out to remove any residual waste. You do this by simply filling the tank with water, then opening the valve to allow a strong rush of water to clean the tank. On a micro level–and this is a little known trick but will get a bit graphic–if you are going to the bathroom and are going to be making a #2, gently tap the flush pedal beforehand so there’s a bit of water in the bowl before you go. The main thing is to make sure to have water in the tank and the bowl before using. Water is your friend. Always make sure there is sufficient water in your black tank. Don’t worry that it will fill up too fast; you’ll almost always fill your gray way before you fill your black.
Utilize Tank Treatments: tank treatments are used to break down the waste and eliminate the odors that may emanate from the tank. Be sure to use it each time you dump your black water tank.

Odor Control

Even though you used the right toilet paper, flushed properly, and used a tank treatment, there are still a few other things you can do to control odor.

Ventilation: if your RV is not equipped with an exhaust fan in the bathroom, you can still ensure good airflow with something as simple as opening the window or roof vent (if you have one). You could also consider installing an exhaust fan. It’s not as complicated as you might think and is a common RV DIY project.
Natural Deodorizers: You can use the same air fresheners that you would use in your home bathroom. However, keep in mind that your RV bathroom is probably smaller than the one you have at home. So don’t use anything with too strong a smell since it can be overpowering in such a small space. Consider using one that absorbs rather than masks the odor. Also, you can pour natural deodorizers like baking soda or vinegar into the toilet bowl or down the drain to neutralize odors.

Preventing Clogs

The best way to handle clogs is to prevent them rather than have to get rid of them.

Regular Tank Flushes: It is essential to flush the tank after each dump to prevent clogs. And make sure that the tank is never completely empty. Fill it with a few gallons of clean water after flushing. (Unless putting into storage.)
Proper Waste Disposal: The only things that should go down the toilet, and therefore into the black water tank, are human waste, RV-safe toilet paper, water, and tank treatments. Period. No wet wipes, feminine hygiene products, other non-biodegradable items, etc.
Use Tank Rinser Systems: A tank rinser, like the swivel stik, is a great tool to wash off anything that might still be stuck on the inside of the tank. It uses a high-pressure spray to help dislodge and clean the tank. A couple of years ago our black tank monitor kept reading that the tank was full even though we had just dumped it. Turns out there was a piece of toilet paper stuck on the sensor in the tank. The swivel stik solved the problem.

Pro-Tip: ICE. If you’re having odor, clog, or residual waste issues, you can solve them with ice. After you dump, put a couple of gallons of water and a 5-pound bag of ice down the toilet into the black water tank. Then drive around for a couple of hours (as you would anyway). As you drive, the ice will slosh around and knock things loose. It should all flush out next time you dump.

Step-By-Step

You should not dump your black water tank too often. You should only try and do so when it’s at least three-quarters full. This will ensure that there’s enough to do a good flush. You should also do so when your grey tank is at least three-quarters full as well. Depending on your family size, you can probably go 3-7 days without dumping (or more).

Since the sensors are not necessarily reliable (as mentioned earlier), there are a few other indicators to let you know when you’re getting to this point. For example, when your toilet “burps”. Meaning, a big air bubble comes up in the water when you flush the toilet.

Although you can dump at a dump station, you will feel less pressure if you do so at a full hook-up campsite. And, in this case, you can do so while your family is doing something else, not just waiting around for you to finish.

Step 1: Gather Your Supplies

In order to prevent cross-contamination and not be in the middle of the process and realize you’re missing something, you should gather all your supplies before you begin.

Gloves: Some people like to use a designated pair of reusable (washable) gloves. However, we prefer not only to use disposable gloves, but we prefer to get a box of black disposable gloves. This way they are kept separate and when wearing them it is a clear visual reminder to not touch anything else.
Sewer Hose: The sewer hose is flexible, contracts for storage, and expands to stretch from the black water tank to the sewer dump site. The flexibility is especially helpful when it’s not a direct line. Due to the shape and flexibility of the sewer hose, my family has taken to calling it the “stinky slinky”.
- Bonus Tip: The stinky slinky takes up a lot of valuable storage space. So we attached a sewer hose carrier to our bumper (circled in red above). It fits our whole hose. As a result, the rest of our black water tank supplies all fit in a bucket. We also find that the sewer hose stays cleaner this way since it’s not coiled up.
Clear Connectors: You’ll need two different clear connectors. You’ll want a 45-degree clear connector between the RV and the sewer hose and a 90-degree clear connector between the sewer hose and the drain in the ground (or sump station). The clear connectors will allow you to monitor the color and see when it’s done draining. (I don’t really see a need to get more descriptive than that.)
Sewer Hose Support: Think of this as a flexible track for your sewer hose. A sewer hose support protects your sewer hose from damage by getting it off the ground. In so doing, it also harnesses the power of gravity to drain your sewer since the hose is on a decline. The flexibility allows you to run your line around and through obstacles. Many RV parks require them to prevent leaky sewer hoses from contaminating their grounds. These supports come in different lengths, so make sure you get one long enough for your sewer hose.
Black Tank Flush Hose: After you dump your black water tank, you’re going to want to flush it out. There’s a special connector for that on your RV; you’ll want a separate hose just for this purpose. Otherwise, you’ll run the risk of cross-contamination and all the risk that comes along with that. We like to use a black hose for this purpose so that we don’t run the risk of mixing them up. But you can use anything as long as it’s different from what you use for your freshwater.
- Bonus Tip: We’ve attached 90-degree elbow connectors to all the valves on our RV to make it easier to connect the various hoses. They don’t tangle, lay easier, and take advantage of gravity with the water flow.
Tank Treatment: You’re going to have to experiment with what works best for your RV and what format you like best. Tank treatments are available in powder, liquid, and pods. Remember, these treatments are used as a deodorizer as well as to actually break down the sediment in the black tank. All the other supplies can be stored together in an outside storage, but you may want to just keep the tank treatment in the cabinet in the bathroom, space permitting.
Bucket: A basic 3-5 gallon bucket with a pour spout is handy to have. You can use it when you need to pour water down your toilet as part of the process. This way you can keep track of how much water you’re using rather than just using a hose or shower head. If you’re concerned about space, you might consider a collapsible bucket. But, as mentioned earlier, you can just store all your black water tank supplies in the bucket. This way they’re all stored together and you just have to grab one bucket and you’re ready to go.
Rocks: You might want something to weigh down your sewer connector that’s screwed into the ground. The pressure released when the tank valve is pulled can cause it to come loose. So, you’ll often find a few rocks piled up near the sewer drain from previous campers. otherwise, you may want to scour for your own (and leave them for the next guy).

Step 2: Warn Your Family

The dumping process will generally take about 15-30 minutes depending on several factors as well as your level of experience and comfort. So, warn your family that the “indoor plumbing” will be unavailable for that duration.

Step 3: Put Your Gloves On

Put your gloves on and confirm that all the grey and black water tank valves are fully closed before you start. Remember: once you put on your gloves, don’t touch anything not associated with the dumping process (face, cell phone, pet, child, clothing, food, fresh water hose, power supply, etc.).

Step 4: Hook-Up

This is where you connect your RV’s sewer to the ground drain. Connect the 45-degree clear connector to the outside port of your tank.

Connect that to the sewer hose, and then connect the other end of the sewer hose to the 90-degree clear connector. The 90-degree connector is threaded to be able to screw into the drain in the ground. After doing so, place a few rocks or other weights on the 90-degree elbow to prevent it from coming loose when you release the valve. (You may need to extend the sewer hose to reach the drain.)

Make sure to double-check that the connections are secure.

Lay out your sewer hose support and rest your sewer hose on top of it. Connect your black tank flush hose to the water supply provided for this purpose and the black tank flush port of your RV. Don’t turn on the water yet!

Step 5: Pull Open the Black Water Tank Valve

Now’s the moment you’ve been waiting for! Pull the black water take release valve to allow the tank to empty. Let it flow for a few seconds, then…

Step 6: Turn On the Water

After the black tank has been draining for several seconds, it’s time to turn on the water connected to the black tank flush hose. As the black tank continues to drain, having the water turned on allows continuous flushing. Now it’s just wait and see. Literally.

Step 7: Wait and See

Watch the clear connectors. You want to notice when the liquid flowing through is just plain clear water. How long this will take really depends on several factors including how big your black water tank is, how dirty it is, and the water pressure at the park. Don’t rush it if you want to ensure a clean tank. Just monitor the flow.

Step 8: Turn Off the Water

Once everything is running clear, it’s time to shut off the water running through the black tank flush hose. Continue to monitor the clear connectors to ensure that all remaining water has drained out.

Step 9: Push Closed the Black Water Tank Valve

Once you’re sure that there’s no more water flowing into the black water tank, you can close the valve.

Step 10: Pull Open the Grey Water Tank Valve

Now that there’s no more outside water flowing into the black tank, you can open the grey water tank and let it flow into the black water tank. This will allow any residual sediment to get washed away in the process which is why it’s so important that you have enough after in your grey tank before starting this process.

Note: If you have more than one grey tank, be sure to drain them one at a time.

By draining the black water and then the grey water, you’re essentially using your sink water to rinse your sewer sediment. Much better than the other way around.

Step 11: Push Closed the Grey Water Tank Valve

Once everything has thoroughly drained out, you can close the grey tank valves. Aren’t you grateful for those clear connectors? Even though your tanks are now completely dumped and empty, you’re not yet done with the dumping process.

Step 12: Tank Treatment

There are a few steps to the tank treatment process. And it will vary a bit depending on the model of your RV and the size of your tank, so check your manual.

But, the basic gist is that you are going to pour a few gallons of water down your toilet (remember the bucket) along with the tank treatment product of your choice. Be sure to read the directions since different products require different amounts of water and the order may vary as well.

More water may lead to needing to dump more often but will also help prevent odors and clogging. Your choice!

Step 13: Clean Up

Gather up all your supplies and put them away for next time. Be sure to clean off anything that may actually still be dirty. Throw out your gloves, if using disposable. And then wash your hands with soap and water (not hand sanitizer). This will ensure that you really aren’t carrying around any residual black tank stuff.

Step 14: Enjoy!

Let your family know that they are free to resume using the indoor plumbing and hit the road! Enjoy the process and recognize that you just conquered most people’s biggest fear of RVing.

The stinky slinky does not have to be the bain of your RVing experience. With a little know-how, any newbie can hack the black tank and hit the open road!

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13 Simple Steps to Hack the Black Water Tank