How to Clear a Stuck RV Black Tank (Easy, Simple Trick!)


Having a clear black tank is an essential part of your RV. A clog in the black tank can spell the difference between a great vacation and an adventure that smells worse than that container that’s been in the back of the fridge for who knows how long.

The problem is there seems to be a load of tips out there suggest one trick or another that’s “guaranteed” to fix your problem. Some of the tips are true to their word others are more harm than good. So let’s start by going through the dos and don’ts of black tank maintenance.

Dos and Don’ts of Unclogging Black Tanks

Dos

There are some methods that are tried, tested and true. Let’s get into the icky details to get your black tank unclogged.

Boiling Water

This solution is one of the most cited solutions for clearing your black tank, and it’s easy to see why. The solution doesn’t take a lot of effort and it’s completely free, but despite how it may seem too good to be true this method actually holds up.

So how does it work?

All you have to do is turn off the water connection to the toilet then boil water and then pour it down your toilet. Do this two or three times. If your toilet itself is clogged you may have to wait so you don’t flood the bowl. The hot water should loosen any material that is stuck in your toilet and then you should be able to flush your problems away.

When dealing with a clog in the black tank, and not necessarily the toilet itself, you can further the effect of this cleansing system by driving around with the water already in the black tank. This will shake up the water and the contents of the black water tank helping to pull off any material that might try clinging to the walls of the black tank.

There are two reasons this solution works so well. First, RV toilets use a low amount of water when compared to a stationary toilet. By adding more water you make it easier to flush away any unwanted materials. Second, the heat of the water will loosen those materials more than cold water will.

It is the second reason for this solution that makes it a good idea to turn off the water connection to the toilet. That way you don’t have cold water mixing with the boiled water.

This is by no means a miracle drug solution. Sometimes the clog will be too much for hot water to take care of. If that’s the case then you will want to employ some of the stronger solutions, listed below, to scrub away at the clogs in the black tank.

There is also an unmerited fear that using boiling water will melt your toilet. Don’t fear your toilet won’t melt from boiling water, so you’ll have no issues pouring boiling water into it.

To see a demonstration of this whole process check out the boil water trick video below.

Chemical Cleaner

A little stronger than just boiled water is using chemicals. Chemicals will often contain acids and bacteria with greater capabilities to break down the excrement and excess toilet paper that clog your black tank.

There are several options to use here. I even heard of someone suggesting using liquid dawn dishwashing detergent. There are better options out there, so I would avoid using your dishwashing detergent on your black tank but if it’s the only option you have it may just work for you.

If you are looking for some quality chemical cleaner for your RV’s black tank then you are in luck, because Amazon has a great selection from some of the best known and highly rated tank cleaning brands out there.

RV DIGEST-IT – Holding Tank Treatment is an eco-friendly solutions to your waste problems RV DIGEST-IT will be able to break down any clogs while preventing terrible odors from coming out of the black tank. A great option to keep your black tank clog-free while not harming the environment.

Extreme Cleaner by Happy Campers is great at dissolving waste and clearing the sensors that you have in your black tank from the waste. The Extreme Cleaner will get the job done fast, and set you up with an easily rinse-able black tank to get rid of the now loose waste.

Unique 41H-1 Holding Tank Cleaner is another eco-friendly option the Unique 41H-1 is focused on making the waste disposal process as easy as possible. There’s no need to even drive around, as some chemicals require, to spread this cleaner around. Just give it 24 hrs to do its thing and you’ll be good to pour out the waste.

Camco TST Ultra-Concentrated Orange Toilet Treatment – With no toxic materials in these drops you’ll not have to worry about what’ll happen when you dump your waste. And whats better than preventing scent? Replacing it. The orange scent replaces the odors the drops eliminate.

Zaal Noflex Digestor is a quick and easy solution. There are no fancy tricks or scents involved with the Zaal Noflex Digestor. It eliminates the odor and clears your black tank. It’s simple to the point digestor.

Toilet Tank Wand

It is not easy to find the right tool when concerned with cleaning your RV’s toilet. Most toilet devices aren’t expecting the toilet to be connected to a large black tank and so the tool doesn’t translate well to an RV’s toilet.

The toilet tank wand is designed for RVs and while there are several options out there are a few that stand out among the others.

Valterra A01-0184VP Master Blaster Tank Wand with Power Nozzle. This device allows you to hook a hose up to the end of the device and send pressurized blasts of water into the pipes below.

This is especially useful in those situations where your tank’s sensor is covered by something in your pipes. It’s a common problem of RV owners to have their tank’s sensor claim that it is full or close to being full just because something is covering the sensor.

The Blaster tank wand is perfect for spraying away from the gunk that is clogging that area, and it’s an inexpensive option to help keep your pipes clean.

Another option is the Camco RV Flexible Swivel Stik with Shutoff Valve. The one downside to the Valterra Master Blaster Tank Wand is that it is a solid PVC pipe that is connected to a nozzle. Which means you don’t have to stick your hand in the toilet, don’t get me wrong that’s certainly a perk, but you have little to no flexibility.

The Camco Swivel Stik is flexible. You bend it to your needs and getting down the pipe in whatever shape fits best. The downside is that it is a little more expensive but for the versatility that it provides, I think it’s worth it.

Don’ts

While there are some great methods, you have probably read up on some of them. Here are some things that you should not put your black tank through when trying to unclog it.

Ice Cube Method

Opposite the boiling water trick’s thought process, you have the ice cube method. The idea behind the ice method is focused on physical force, and using that to shake up whatever is clogging your black tank.

So you load up your black tank with some water and a fair amount of ice and then drive around to shake the ice around as much as you can. But this isn’t really all that effective. Ice isn’t all that rough a substance, to begin with, it’s kind of known for things slipping off of it.

Well, that means it’s not the best material to jostle around while trying to scrub those hard to reach places in the black tank. There is a rather minimal scrubbing effect that you’ll get from the ice cube method but it is not really worth the ice and gas needed to use this method.

If you were surprised by this methods appearance on the Don’ts list or would just like more information than check out thefitRV’s article on the topic.

He does a great job looking into this method. If you don’t want to read the article then you can watch his video of the experiment with the ice cube method below.

Self-Power Washing

When it comes to power washing there are plenty of services out there that will wash your black tank for you, but when you are contemplating taking the task on yourself I would urge caution.

Using high pressured water in a black tank can lead to breaking the tank causing even more problems through leaks than you had in the first place.

There is a lot of back and forth on this topic in the community with some people even taking power washing as a first step. It will clean your black tank the issue is sometimes it does too good a job. So steer away if possible.

Pressurized Air

Pressurized air is one of the worst options for your RV’s black water tank. Air is not nearly as effective at cleaning as water is, and you still have the problem of too much pressure in your black tank leading to potential damage.

Pressurized air more often then not leads to the pushing the refuse in the black water tank into the even harder to reach corners that will be harder to take care of later. Overall, this will make your job harder when looking to clean your black water tank out in the future.

Plunger

The plunger is just about everyone’s going to toilet clog clearing friend, but not in an RV’s toilet. The issue here is that in an RV’s toilet you open a valve and gravity does all the work. So there is really no point in using the plunger.

Some people have even noted that they have damaged their RV’s toilet by using a plunger. Since there is a seal placed around the valve that is closing and opening the toilet you can often harm that seal by using the plunger.

So, unfortunately, you’ll have to ignore plungers when you have plumbing problems in your RV. Trust me its for the best.

Preventing Clogs

The main reason that we face toilet issues in an RV is that we are so used to the stationary toilets in our homes that we don’t really know how to transfer our bathroom habits to what best suits an RV.

For instance, using regular household toilet paper can be really hard on an RV because RV toilet’s use less water than your toilet at home uses, as such using as much toilet paper as you are used to at home can cause clogs.

Below I’ll talk about ways to prevent clogs.

Use RV Toilet Paper

RV toilet paper is biodegradable toilet paper that will dissolve with the low amount of water that an RV toilet flushes. This will prevent the build-up of undissolved toilet paper that plagues many black tank clogs.

Now there are some specialty toilet paper brands that some recommend as the best and only option for your black tank. In truth, there are many different brands and kinds of toilet paper that may work just as well if not better than some RV toilet paper.

To learn how to test your toilet paper check out the Gone with the Wynns video below. This RV owner shows you how to test any type of toilet paper to see if it’s up to the task of serving in your RV.

In short, your best options will likely be RV toilet paper and the next best option is toilet paper that is marked as septic safe. But, you can always test your preferred toilet paper with the above method.

A great option that I prefer to use is the Thetford RV/ Marine Toilet Tissue. It breaks down well in low amounts of water.

Keep the Tank Clean

If your tank is clean then there won’t be any clogs or build-ups. So keep it clean. There are many methods described above for cleaning the tank when it is clogged you may use those methods when normally cleaning your black tank if you want, but normally I stick to using a chemical agent that will break down clogs reliably.

This way I can buy in bulk and never have to work about not having the chemicals I need.

I suggest using RidX for this. It’s a chemical that contains enzymes and bacteria that will eat away and break down any toilet paper and refuse that you have in the black tank.

Whichever chemical or cleaning process you choose to use, you’ll want to clean your black tank frequently. Cleaning it weekly is the best option but at least clean it every other week that way you don’t have to worry about build-ups in your black tank.

Frequent Flushing

Since RVs use less water than your stationary toilet back home you can try to rectify this issue by using more water. Some RV owners even suggest flushing twice.

I don’t personally feel flushing that often is necessary but it’s not a bad habit to develop. So flushing an extra time every now and then can lead towards a cleaner happier black tank.

More important than flushing extra after you go to the bathroom is flushing before it. You never want your black tank to only have waste in it. This will help with other things, like the smell, but doing so will keep the tank in a much cleaner position.

To fill the tank with water just fill the toilet and flush. Some owners suggest adding 7 to 10 gallons of water but normally one full flush should keep you pretty safe from clogging. If you find yourself still getting clogs though you may want to increase the amount you start off in your tank initially.

Don’t Flush Toilet Paper

One solution that some suggest, though personally, I feel its a little extreme, is to not flush your toilet paper at all. When doing this you’ll want to have plastic bags, like large Ziplocs or grocery bag to wrap up your waste.

So instead of flushing the toilet paper you just put it in those bags instead. Do this and you’ll never have to worry about toilet paper clogging your black tanks, because there won’t be any toilet paper in your black tank.

The extra benefit of this is it doesn’t matter what toilet paper you use. Nothing gets flushed so there is nothing that is going to get clogged. So you can use whatever toilet paper, or wet wipes you want, so long as you don’t flush them.

Fixing a Stuck Black Tank Valve

Sometimes the issue isn’t clogs within the black water tank but a sticky black water tank valve. These can occur quite frequently as the valves aren’t really designed to slide in and out with precision.

Add to that the large amount of waste that is being pumped through the pipes and you have a frequent cause for a problem. So how do you fix it?

It’s not the easiest thing to fix your best bet will be to prevent it. So if you aren’t facing this issue yet and you want to continue to avoid the problem then consider adding more lubricant of some kind to the black water valve.

Preventing a Stuck Black Tank Valve

You have several options to use as a lubricant. WD-40 works great, but others suggest Vaseline as a good option, and there is always lubricant made specifically for black water tank valves like Thetford RV Drain Valve Lubricant.

As a word of caution, some have suggested using oil, such as common cooking oil to lubricate the black tank valve. Don’t do it. Cooking oils will eat away at the seals around the black tank valve. Since you want to avoid replacing them as much as possible stick to the less corrosive options.

If you feel, whether from age or bad lubrication, that your black tank seal needs replacing or that it is a lost cause to try to fix the constantly sticking black water valve then there is no need to worry, you can just replace it.

Waste valves are not all that expensive so don’t suffer through a bad valve if you don’t need to. Having the right valve can make all the difference. No one wants to need to clear their tanks and find that they can’t because the valve is stuck. So make sure you are doing the maintenance necessary to make sure that never becomes a problem.

Troubleshooting a Stuck Black Water Valve

What if it’s too late? The valve is already stuck and your RV needs to go what now? Well, there are a couple of tricks that can be used to address the problem immediately. I wouldn’t consider any of these permanent fixes, and if you find your black water valve constantly getting stuck then it’s time to get a new one.

Try adding some lubricant inside and outside the black tank valve. This can work with official lubricants or with some homebrewed solutions. using Vaseline is a good option, as well as dishwashing detergent. Both will clean up the tank’s inside as well as provide some lubrication for the black water valve.

For the Vaseline take a handful of Vaseline and add in about a quart of warm water and then send it down the toilet. You may want to drive around a bit to help spread the Vaseline get all over the black tank so that you can get as much of the lubricant as possible onto the valve.

For the detergent pour the whole container into the toilet. You should have plenty of liquid from the detergent alone but you can always add more water if you don’t feel like what you have is enough. But you don’t want it to get too bubbly as that can make it hard for the lubricant to reach and stick to the valve.

If you aren’t seeing any progress, you can always try tapping the valve with a hammer to try to use the vibration to clear off any excess refuse that has gathered around the valve.

If all else fails then you’ll need to take it to an RV technician. Black water valves can be frustrating to deal with but luckily they aren’t that expensive so it won’t cost you an arm and a leg to fix your problem.

Geoff Southworth

I am a California native and I enjoy all the outdoors has to offer. My latest adventures have been taking the family camping, hiking and surfing.

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