Make Your Own RV Black Tank Cleaning Bombs

Want a better way to clean your RV black tanks? Try these RV Black Tank Cleaning Bombs!

RV Black Tank Cleaning Bombs

Disclosure: This post contains affiliate links for various products below. You get the same low prices and we earn a small commission to help us buy more RV tailgating gadgets. Or game tickets if you go on a shopping spree.

If you hang out long enough in the RV groups, you’ll see cross-over with tiny homes and quite a bit of frugal living sites. Something about the RV lifestyle lends itself well to these groups.

And popular among all of these groups is a certain do-it-yourself mentality.

Even for cleaning products.

Which is how I found out about toilet bombs.

I had heard of bath bombs before and these are basically the same thing. You drop them in some water, they fizz up, do some magical cleaning action and then you flush the toilet bombs away. All good.

And naturally, I was like “this is easy! I can do this” and “I wonder if they would work in the RV black tank?”

This innocent of questions lead me to an entire night of scouring the interwebz to see if the components would work in RV black tanks.

The Geo Method for RV Black Tanks

There are a few basic methods for keeping black tank odors in line. You can buy chemicals at Amazon or Camping World. Or you use the Geo Method.

The Geo Method uses a couple of basic household components – Calgon water softener and Borax laundry booster. You mix all of these in the tank. The Calgon keeps waste solids (yes, the eeewww stuff) from sticking to the sides and building up in the tank. The Borax cleans it all up.

But I’m always looking for a better way.

Enter… the toilet bomb!

Toilet Bombs for the RV Black Tank

Most of my RV use comes during football season, when I’m taking the RV out sometimes weekly. I’m also dumping weekly. With so much going on, I continue to look for ways to make things easier.

Quicker.

Less of a hassle.

So instead of having to haul several different containers out, why not have a handy little “ball” of stuff to throw down the toilet during the weekly cleanup?

If you’ve been using the Geo Method, you’ll already have two of the ingredients on hand needed to make RV black tank cleaning bombs! The Borax and baking soda. The third ingredient is citric acid.

Citric Acid in the RV Holding Tanks

I can hear you from here:

“Oh, acid! We can’t be putting that in our tanks! It’s not safe!”

Have no fear! Citric acid is fine for your RV tanks.

First, it is naturally occurring in lemons and limes. Citric acid is edible and can be found in a lot of foods you eat or drink, like soft drinks or baking in place of lemon juice.

Ever had sweet and sour candy? That white sour flavoring is… yep, you guessed it – citric acid. You’ll also find citric acid in many ice creams. It is used in canning operations (you know, those mason jars you love to paint and use at your Southern tailgates).

If you look at the ingredient list on many of your beauty products, you’ll find citric acid. Shampoos, chemical peels for your face, and many body scrubs all have citric acid.

Citric acid is also commonly used as a cleaning agent for membrane filters in water treatment process.

It’s also used to remove lime buildup in boilers and evaporators. Many boaters recommend using citric acid to clean fixed fresh/drinking water tanks. As a natural ingredient, citric acid typically has no bad effects on lakes when the tanks are emptied.

It is even used to clean aquariums (where trace residue of other cleaning products could be lethal to fish).

Citric acid is a common ingredient in those commercial black water tank cleaners. Even the makers of RV Digest-It recommend using citric acid to remove calcium buildup in your black tank:

If you are traveling in a hard water area you sensors will likely stop working because of calcium buildup on the sensors. If you catch it early RV Digest It should be able to break down the greases and oils that cause the calcium to stick to the sensors, however it it’s been building up over a long period of time the bacteria may not be able to penetrate the calcium if this is the case we recommend putting citric acid in your tank for a day or two and then empty and rinse the tank to remove the calcium.

It’s considered a relatively weak acid. But it has great power when it comes to cleaning.

All in all, that was a long way of saying: citric acid is safe for your RV black tank! And you’ve probably been putting some in your tanks all along.

(You can buy citric acid at Amazon in larger quantities than you can typically find at your local grocery store. And cheaper too! Might as well get the baking soda and Borax while you are at it.)

See Also: Maintaining Gray Tanks: The Other RV Waste Tank

Without further ado, let’s make the best homemade RV holding tank treatment!

Black Tank Cleaning Bombs

Yield: 9 Cleaning Bombs
Make these easy cleaning bombs to keep your RV black tank working in pristine condition.

Materials

  • 1/3 c Borax
  • 1/3 c Baking Soda
  • 1/3 c Citric Acid
  • 1 tsp. Water

Instructions

  1. Mix Borax, baking soda, and citric acid dry ingredients in a gallon size Ziploc bag. Mix well.
  2. Add several drops of water, to allow ingredients to bind together. Mix well. May need to add several more as you go. Do NOT over-wetten (that's a word, right?).
  3. Pack tightly into silicone molds. Let dry overnight.
  4. Pop out of molds. Let the RV Black Tank Cleaning Bombs continue to dry for 1-2 days.
  5. Store in air tight container until used.

Notes

The key here is to keep the water to a minimum. Use only the smallest amount absolutely necessary to get everything to stick together.

If exposed to air during storage, the bombs will absorb moisture from the air and may stick together or become difficult to remove from the storage container (if odd size top)

Recommended Products

Disclosure: This post contains affiliate links for various products below. You get the same low prices and we earn a small commission to help us buy more RV tailgating gadgets. Or game tickets if you go on a shopping spree.

Buy these products on Amazon: citric acid, baking soda and Borax.

You’ll notice a bit of fizzy action when you add the water. This is normal.

The key here is to keep the water to a minimum. Use only the smallest amount absolutely necessary to get everything to stick together.

Otherwise, the final product will bloat in the molds and won’t be all pretty like. You’ll still be able to use the toilet bombs but they won’t be neat little balls that you can drop down the toilet and into the black tank.

Your best bet if this happens is to crumble them up and then shake into the toilet as needed. Also great for using in the gray tanks.

If you want to skip the molding step, you can also keep all the dry ingredients mixed up in a small shaker bottle. I’ve got an empty Bounce Bursts bottle (for those small smell good satchels) that is perfect for this – even has the handy cap to measure it out.

Using the RV Black Tank Cleaning Bombs

After you have dumped your black tanks, just drop one of these RV black tank cleaning bombs into your toilet.

Let it fizz up with the water in the toilet (and clean the toilet) and then flush it.

Make sure there is a good layer of water in the black tank, just like you’d do with the Geo Method.

The cleaning bombs will continue to work, scrubbing away at the gunk inside your tanks. It’s even better if you drive the RV around, to get the agitation like you would in a washing machine or dishwasher.

Like all other things that you use around the RV, a little goes a long ways. No need to put buckets of this down the drain.

Use only one cleaning bomb until you determine that you need a second. My guess is that you will need only one unless you have a really bad tank problem on your hands.

Works in the Gray Tanks Too

These Black Tank Cleaning Bombs work great in your your gray tanks as well. Thus, RV Black Tank Cleaning Bombs are truly RV Holding Tank Cleaning Bombs.

Fill the sink or shower basin with some water, drop a cleaning bomb in it (clean the sink or shower) and then drop it into the gray tank.

Keep a little water in the tanks, even while the RV is in storage between trips. This will allow the components to keep cleaning the tanks and keep the seals moist.

See Also: Tips to Help You De-Winterize Your RV and get ready for spring camping and tailgating

These Cleaning Bombs Work at Home Too!

The cleaning bombs also work great for your bricks and sticks toilets. Just drop one it, let it fizz for a little while and flush away.

If you are using these cleaning bombs for your home toilet, you can also add drops of essential oils for added odor control. I figure though that the essential oils aren’t necessary for your RV black tanks.

The RV black tank cleaning bombs also work great in your dishwasher.

See Also: Preventing RV Odors

Try It and Let Us Know if the Cleaning Bombs Work For You!

RV Black Tank Cleaning BombsSo now, why don’t you try these RV Black Tank Cleaning Bombs and let us know if they work for you. Comment below!

You may find that you like this homemade RV holding tank treatment better than other RV black tank methods.

Buy these ingredients on Amazon:
Citric Acid
Baking Soda
Borax

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Kimberly

Kimberly is the owner of a Tiffin 34PA and the former owner of Starter RV, a 1990 Winnebago Chieftan. She can be found cheering for Georgia Tech, traveling the world, or working on the RV (because there's always something to do on the RV). Don't ever underestimate what she can whip up in the kitchen or accomplish on no sleep. Find out the latest from Kimberly by signing up here.

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19 Responses

  1. Dawn Mork says:

    Tried making these today, and the bombs keep expanding out of the molds. What am I doing wrong. I punch them back down but they have risen out of the mold and onto the countertop every time. I made 3 batches, each time using less water but they have all reacted the same way. Do you know if they will they still work? Thanks

    • Kimberly says:

      Hi Dawn! It really is the amount of water that you used. You really want to use only a couple of drops, just enough to get the dry ingredients to stick.

      The good news is that they still work! They just are not the cute little bath bomb like creations. You can just crumble them up and drop them in the toilet, sink, or shower, like you would if they didn’t expand. When they hit the water, you should still see the fizzing action. I always like to let it sit in the toilet for a minute to clean the toilet. 🙂

      If you still can’t get them to work, just mix up the dry ingredients really well and put them in a shaker. I like the Bounce Scent Booster shaker since it has a measuring cup on top. Then just dump a small amount into the toilet directly. Confession: a lot of times I don’t even make the toilet bombs and just use the dry ingredients!

  2. Barbara says:

    Do you still put the blue enzymes in between draining?

    • Kimberly says:

      Hi Barbara. I have never used the blue enzymes in my tanks. Prior to the Tank Bombs, I used the Geo Method (Calgon water softener and Borax laundry booster) to control the odors and keep things running smooth in my RV tanks. The Tank Bombs replace all the other chemicals and cleaning agents that you would place in the RV black tanks.

  3. BARBARA says:

    If I wanted to just keep as the powder and not turn into “bombs”, how much would I use?

    • Kimberly says:

      Barbara, depending on the size of your tank, probably 1-2 tablespoons. It may take a little experimentation to get it right, just like you probably did with the Geo Method.

  4. GWM says:

    Would it be safe to add some boiling water after flushing the toilet bomb and running few gallons of water. We have noticed some drain flies and are trying to get rid of them. Boiling water seems to help and hopefully getting the tanks clean with this method will solve the problem.

    • Kimberly says:

      It should be ok to add boiling water to the tank. As it cools, the extra water will help keep the sludge from forming the Big Pile of Poo Doom!

  5. Terri A Nixon-Warden says:

    How big are the bombs your using: marble, golf ball, tennis ball?

  6. Shannon says:

    so if you add this after you dump the tanks am I correct that you leave the bomb plus some water in the tank – that it stays until the next time you use the RV?

    • Kimberly says:

      Hi Shannon! Yep, that’s exactly what I do. Dump the tanks. Then add a little freshwater to line the bottom of the tank and drop one of these in. Use the tanks, empty and repeat.

  7. Jennifer says:

    With these bombs is there any need for water softener/Calgon?

    • Kimberly says:

      Jennifer, I typically do not use a water softener. The Borax is a multi-purpose household cleaner that removes hard water deposits. Make sure to add water when you drop them in the black tanks so that the Borax can dissolve.

  8. Ken says:

    Sounds like a great idea I am going to try it this year, thanks for the post !

  9. Webdy Hull says:

    I made these and noticed that you don’t need drops of water. I put the mix in a bowl and squished with my hand to break up the chunks of the borax. After about a minute or two – you have to be patient – that is the key here, the mixture did get some moisture to it and was moist enough to put in molds. YOU DO NOT NEED ANY WATER. Just WAIT – then pack them tightly in the molds and they won’t expand.

    • Kimberly says:

      Wait, who has patience? 🙂 Just kidding.

      A lot will depend on the humidity when you make the black tank cleaning bombs on whether you can just wait for them to absorb the water from the air. If you are in the desert, don’t depend on it working well. Unless you’ve just taken a shower in your RV or something like that.

      But you do bring up a good point, that you don’t need a lot of water to make the cleaning bombs. Just a little bit goes a long ways.

      Thanks for trying them out! Hope they work well for you. I know that they really keep the smells in my black tank down and my black tank sensors still work.

  10. Whitefishtom says:

    If a black tank needs revitalizing including getting sensors to work, how much should be put in with a full tank?

    • Kimberly says:

      It will depend on the size of your black tank. For mine, I use a golf ball size Black Tank Cleaning Bomb unless it is just giving me lots of problems lately (usually smell) then I’ll drop two in. But I do this at the beginning of the cycle, before it is full. Drop the cleaning bomb in, add some water and then go on. If it gets to smelling before it is time to dump, I may add the second in with some more water.

      Because I am an RV tailgater, it means that I am constantly on the move between games and stadiums (and some cool parks and RV campground spots). This movement is great to help keep the RV black tank in good working order. It allows that water + cleaning bomb to slosh around, cleaning the sensors and washing down the sides. That is really the best way to keep the RV black tanks in good working order – water + cleaning bomb + movement. And using the RV black tank back flush system.

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