How To Clear A Clogged RV Or Camper Blackwater Tank

The blackwater tank in your camper or RV is something you might not like to think about too often.

Unfortunately, if it becomes clogged you won’t have much choice in the matter.

After all, the toilet is an essential part of your RV or camper. As the blackwater tank is a critical part of that system, a clog needs to be addressed immediately.

In this article I have covered different methods you can try to clear a clogged RV or camper blackwater tank.

You will also learn everything you need to know about maintaining your blackwater tank and preventing future clogs.

Understanding Your Blackwater Tank

RV Black Water Tank

Knowing how your blackwater tank works is useful for a few reasons.

Firstly, you will have a better understanding of what can cause problems.

Next, you’ll know why and how good tank maintenance practices are important.

Finally, you should understand how everything in your RV or camper works to the best of your ability. This is particularly true of the utilities—electricity, gas and plumbing.

Your RV or camper toilet system is not the same as that of a residential toilet.

Waste does not just disappear into sewer pipes underground—it ends up in your blackwater tank.

Unlike your freshwater and grey water tanks, the black tank holds solids too.

These consist of toilet paper and human waste, and whatever else you decide to flush down the toilet.

A properly maintained blackwater tank should be capable of breaking down these solids over time. Water mixed with a chemical or natural solution inside the tank will do the job.

All of this unwanted waste reaches the blackwater tank by way of a pipe connected to your toilet. As you may have guessed, this connecting line shouldn’t be neglected either.

Are you curious to see what a blackwater tank looks like inside?

Here’s a quick video showing you the inside of a new blackwater tank being flushed:

Why Is My Blackwater Tank Clogged?

You’re likely wondering what happened to clog your tank.

There are several conceivable scenarios that led to the clog:

Waste Buildup

The most common clog cause is a buildup of waste. Too many solids collecting can block up your tank or your lines. Just to make it clear, we’re talking about toilet paper and feces.

This can occur if you haven’t been dumping the tank often enough.

Not cleaning the tank and poor maintenance can also lead to waste building up in the line and tank.

If your blackwater tank is equipped with sensors, you may be wondering how waste could build up without you knowing. These sensors can fail over time—especially if they are neglected.

Dirty sensors can give you inaccurate readouts. You may think your tank is only half-full when it is already full to the brim.

Flushing The Wrong Items

There are certain items that shouldn’t be flushed, such as wet wipes or sanitary products.

These things can encourage a clog to form, especially if you are flushing them often.

Dumping Too Often

It sounds counterintuitive, but dumping your tank too often can cause clogs.

Frequent dumping will dry your tank out, which is a situation best to be avoided. Waste and other solids can stick to dry tank walls and eventually build into clogs.

Get Ready To Clean

Man Wearing Rubber Gloves

Before you get busy fixing the clog, don’t forget to stay safe.

Just because you aren’t dealing with gas lines or electrical wiring doesn’t mean there is no risk involved.

1. Take Safety Precautions

I shouldn’t need to tell you that exposing yourself to human waste must be avoided at all costs.

Not only is it disgusting, but contact with human feces can make you physically sick.

You might also be handling serious chemicals to get rid of the clog. Make sure that you have a good pair of gloves on before you start working.

Since you’re going to be up close and personal with your blackwater tank, think about covering your eyes. You can invest in a pair of safety goggles which are adjustable to fit different head shapes and sizes.

It’s always helpful to have a friend or family member assisting you.

Some of the methods are easier to carry out with two people. When handling a job like this, moral support doesn’t hurt either.

If you are the type who gets queasy just dumping the tank, don’t force yourself to fix the clog.

Not everyone is going to be comfortable delving into the inner workings of an RV or camper sewage system.

Hiring a professional to remove the clog on your behalf is always an option. Note that seeking professional help will always cost you more than taking the DIY route.

2. Clean The Waste Pipe

Unclogging Toilet

The clog might not be located in your blackwater tank; your waste pipe could be the source of the problem.

If you can dump your blackwater tank out but there is still a clog, your waste pipe is likely at fault. If you can’t remember the last time you cleaned it out, you may have what are known as pyramid plugs.

Pyramid plugs are an interesting name for a repulsive phenomenon. These are the result of a build-up of waste that eventually hardens. The more waste that collects without intervention, the more pyramid plugs you will have.

To remove pyramid plugs, you’re going to have to get hands-on. If your toilet bowl itself is clogged, put on your gloves and protective goggles.

You’ll need to grab a toilet snake and prepare to put some effort in. Get an auger that is extra long and flexible.

You will probably be able to feel the pyramid plugs as you poke around. Take your time until you feel like the line is all clear, even after the main blockage dissolves.

Another option is to use a toilet wand with a motor. As I discuss further down, make sure that you are using one that is safe for RV or camper toilets.

3. Check For Other Potential Issues

Paper In Toilet

The next step is eliminating the possibility of other issues (minor or major).

You don’t want to waste your time and effort trying to fix a clog that doesn’t exist.

Common signs of a clog include a bad smell from the toilet or trouble dumping the tank. However, there are several other problems that may be at the root of these symptoms:

Leaky Toilet

Your toilet might be leaking—check for water on the floor of your bathroom.

Your toilet might be improperly secured to the floor of the bathroom. If this is the case, it is fairly straightforward to fix.

Dirty Toilet

Waste collecting in your toilet can be responsible for some powerful odors. Give your toilet a thorough scrub-down and see if it helps.

Broken Or Stuck Toilet Flapper

A broken toilet flapper or ball valve could be behind the stink. This mechanism is responsible for forming a seal between the blackwater tank and the toilet itself.

If this seal is not airtight, smells will escape. Check to see if waste or toilet paper is caught in the flap, keeping it open.

If it’s broken, you’ll have to switch it out for a new one.

Learn how to replace the seal in this video:

Improperly Set-Up Tank Valves

Testing your tank valves can save you a lot of time. Perhaps you forgot to open a valve, or connect the sewer line properly. This is the best case scenario—nothing more needs to be done.

4. Don’t Make The Problem Worse

Forbbiden Using Of Toilet Wand

Let’s get on the same page about things to avoid when it comes to unclogging blackwater tanks. Approaching a clog the wrong way can be disastrous.

You don’t want to cause irreparable damage to your tank.

Additionally, trying these strategies out can have terrible consequences, like waste going where it shouldn’t.

Motorized Toilet Wands For Regular Toilets Are Unsuitable

A toilet wand (or snake) is going to come in handy when you’re unclogging your tank. A motorized one can save you some elbow grease, so why not use one?

It isn’t wise to use a motorized wand which is intended for a regular toilet. You can accidentally end up puncturing your tank. Only use models designed for RV or camper toilets.

Don’t Use A Pressure Washer

Pressure washers might sound like an easy solution to a clog.

Water blasting at high pressure will definitely get rid of even stubborn buildup, right?

Well, yes—it might work to break down the clog. But it can also accidentally cause waste to splash around everywhere.

If this isn’t enough of a reason not to use one, consider the risks to you and your tank. A pressure washer might also break your tank and potentially cause you injury.

Pressurized Air Is A No-No

Using pressurized air comes with the same problems as pressure washers. Your tank can crack or break apart due to the pressure.

Even if that doesn’t happen, you won’t only be targeting the clog directly. Other waste in your tank will blow around the tank and possibly out of it, towards you.

5. Try Cleaning Your Blackwater Tank

Washing Black RV Tank

Try giving your tank a good clean before you get to more tedious tactics.

If the clog is not too serious, cleaning your tank might just be enough. If not, at least you tried the most obvious step.

You probably already have a product you use to clean out and maintain your blackwater tank. If you don’t, this could very well be the reason you are dealing with a clog.

These powders or liquids are used for general maintenance of your blackwater tank. You pour them directly into your toilet and they work to break down solids.

It is necessary to use these products on a regular basis. There’s no such thing as a self-cleaning black water tank.

You might prefer to use products with natural ingredients instead. These are less harsh on your tank. They also won’t leave behind the stench of chemicals in your bathroom after you use them.

Try using a rinser for RV or camper wastewater tanks. This lets you flush out your black tank without risking backflow or damage.

6. Unclog Your Blackwater Tank Using Products

Preparing To Bleach RV

If cleaning your tank and line didn’t work, it’s time for the big guns.

There are a range of products you can use that will work to break down even the sturdiest of blockages.

You should know that these are different from blackwater tank maintenance products. They tend to be stronger and are specifically for tackling clogs.

Natural Products

All-natural solutions are not just for maintaining your tank. You can find products that make use of large quantities of enzymes or probiotics to break down clogs.

These work by literally digesting the buildup that forms the clog. Depending on the brand, they can target organic waste as well as artificial waste (e.g. toilet paper).

Chemical Products

If you prefer to use a chemical-based product, choose one that is appropriate for RV or camper blackwater tanks.

7. Unclog Your Blackwater Tank Without Products

Flushing Black Water Tank

There are ways you can clean out your blackwater tank without the use of specialized products.

You might want to give these a try if you can’t wait for the product you ordered to arrive.

One of the methods you may have heard about is using ice. Supposedly, filling your blackwater tank with ice and driving around will dislodge clogs. But this might not be the best answer.

There are a lot of variables that come into play with this approach. The size of your tank, how much ice you use, how bad the clog is, etc.

The Geo Method

The Geo method is a tried-and-true technique for unclogging blackwater tanks.

All you’ll need is Calgon water softener and a transparent sewer hose adapter. You’ll need the adapter to see if the water is coming out clear or not.

Begin by hooking your black tank up to a sewer pipe. Dump the water softener down your toilet into the blackwater tank.

You can be generous with the amount: water softener won’t harm your tank walls.

Here’s where having a partner will come in handy. One of you should flush the toilet repeatedly, while the other monitors the sewer hose adapter.

This might not totally dissolve larger clogs, but it will clean your tank out. Watch this video to learn more about the Geo Method:

8. Clearing A Clogged Blackwater Tank On The Road

Pouring Hot Water In Toilet

What happens when you discover a clog in the middle of a trip?

Some of you may be dealing with this very situation right now.

Ordering products and tools to clear a clog can be difficult when you are far from home. Finding a local professional to help may not be easy either, and it can be expensive.

Don’t worry, you won’t have to turn your camper or RV around and go home. You can try this method to break the clog down using readily available items.

Warning: do not give this a try if your toilet is already near-to-overflowing. The same goes if your tank sensors are telling you the tank is full and it won’t dump. You don’t want backflow.

All you will need is boiling water—and plenty of it. Boil three or more mid-sized pots worth of water and pour down your toilet. Let the water sit there for a few hours.

If you have an arctic package on your RV or camper, make use of it. Switch the blackwater tank heaters on for extra warmth.

Ideally, when you dump your blackwater tank, any clogs should be softened by the heat.

Preventing Future Clogs

Taking Paper From Toilet

It’s easier than you think to prevent clogs from forming in your blackwater tank.

Keeping up on maintenance and a little common sense goes a long way.

Watch What You Flush

Remember how I mentioned some things shouldn’t be flushed down your RV or camper toilet?

Take that seriously. No sanitary items, wipes, or paper towels should go down your toilet.

This applies to heavy toilet papers too. You can buy special types of toilet paper that are designed with RV or camper toilets in mind. These toilet papers are able to break down faster than other brands.

The faster the toilet paper breaks down, the less likely it is to block up your blackwater tank.

Learn How Often To Dump Your Tank

As I’ve mentioned, you shouldn’t be dumping your blackwater tank too infrequently or too often.

Let your tank become at least two-thirds full before you dump it via portable tanks.

Don’t forget, drying your tank out can cause clogs. Make sure there is some liquid (water and a maintenance product) in your blackwater tank at all times.

Regular Maintenance

Use maintenance products on your tank as often as possible.

The cleaner you keep your tank and waste pipe, the better.

Remember to keep your sensors clean too, so they provide you with accurate readings. Staying on top of blackwater tank maintenance will also reduce unpleasant smells.

Good Habits To Practice For Your Blackwater Tank

Toilet Water Flushing

There are good practices you should follow when using the toilet in your RV or camper.

This will help you to lower the risk of clogs forming.


If there’s solid waste in your toilet, flush at least twice. This is a precaution to make sure everything passes cleanly through the waste pipe.

Educate All Travelers

If you are traveling with children or anyone new to the RV or camper lifestyle, educate them. Explain that these toilets are more fragile than toilets at home.

Emphasize that nothing else should go into the toilet but toilet paper. You don’t want to find out mid-trip that your blackwater tank is clogged due to a careless passenger.

Use Products Specific For RV Or Campers

An unclogging product you use at home might damage your pipes or tank. RV and camper sewage systems are not made of the same materials as residential ones.

To play it safe, only use products that are specifically for RVs or campers.


I hope you found this step-by-step guide helpful. Experiencing a clogged blackwater tank is a frustrating experience for any RV or camper owner.

Taking good care of your blackwater tank will lessen the chances of clogs.

So will practicing good habits when it comes to using the toilet in your RV or camper.

Do you have any other tips or techniques for unclogging an RV or camper blackwater tank?

Please share your knowledge with us in the comments. If this article helped you, share it with other camper or RV owners.

6 thoughts on “How To Clear A Clogged RV Or Camper Blackwater Tank”

  1. I found on my black water tank that the valve wasn’t fully opening. So each time I was dumping the tank, it was never emptying. My sensor was also showing my tank was still full. Not the best job to do, but I ended up replacing the valve. Once I pulled the pipe off, everything dumped out. EVERYTHING!!! Once the new valve was installed I flushed the tank out to remove anything left inside. Which also allowed me to test the valve out multiple times.

    Thanks for the article!!

    Bob Krimmer

  2. I will try to use your way to solve my RV`s problems. Thank your useful post, I will read more about your new posts.

  3. The handle to open and close the black water to dump it will not close. As soon as i let go of the handle it opens up. I have tried to clean it inside the toilet. Ran the water from the garden hose thru till it was clear. I had the handle replaced but it was doing the same thing again. It wont close so when you cap it. Black water fills the drain when you take the top off to empty the leakage runs out.

    1. The slider to stop and release the waste under the rv is stuck close and the knob broke off now the toilet won’t drain and is filled to the rim, how can I fix that slide?

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