How To Clean Black Water Tank With Vinegar & Baking Soda

If there's one job that you probably hate the most when RV'ing (I know I do) and that's cleaning out the black water tank.

There's a safe, natural and effective cleaning hack involving baking soda and vinegar which is proven to be a cost effective and efficient solution to get rid of unpleasant odors and blockages and deep cleans your black water tank.

So how do you clean a black water tank with baking soda and vinegar?

To effectively clean a black water tank, you’ll need to do the following:

  • Dump the sewage at a designated sewer station.
  • Flush the tank with clean tap water.
  • Pour two cups of white vinegar directly into the black water tank.
  • Add a cup of baking soda to activate the chemical reaction.
  • Allow the mixture to bubble before adding a gallon of warm water to flush the tank. 
  • Optional: Add a cup of vinegar to a gallon of warm water and flush it down the toilet to clean the pipes.

You don't need much to clean out your tank, and you probably have most of the ingredients in your pantry. Everything you need to make this safe, natural cleaner is listed in the step-by-step guide below.

Why Vinegar and Baking Soda Effective In Cleaning Your Black Water Tank

When combined, vinegar and baking soda form a safe and effective cleaning agent for your black water tank. 

Vinegar is an acid with a pH level of 2-3. It's effective in dissolving minerals and breaking down hard water deposit buildups in the tank. 

Vinegar also has deodorizing properties, neutralizing unpleasant odors and acting as a natural mold killer. 

Baking soda, on the other hand, is a basic compound with a pH level of 8-9. This alkaline white powder is great at dissolving debris and grease that can cause drain clogs in your black water tank.

Baking soda is also handy in removing tough stains and has odor-neutralizing properties.

When you pour vinegar into your tank and add the baking soda, a chemical reaction releases carbon dioxide gas. You'll hear a fizzing sound, and you'll be able to see the mixture bubbling. 

The carbon dioxide gas in this natural cleaner breaks down and dissolves any particles, grime, deposit buildup, or grease in the tank. You can leave this mixture to bubble for around 20 minutes to ensure the dirt and buildup have been broken down. 

Even though the vinegar and baking soda combination is safe to use in your black water tank and won't cause any corrosive damage, it's best to flush the tank with warm to hot water after the reaction.

This will ensure any particles that have come loose are removed from the tank. As an extra benefit, when vinegar is mixed with hot water, it can help to eliminate bacteria such as Salmonella and E. coli.

How Often Should You Clean Your Black Water Tank With Vinegar & Baking Soda?

Mixing the baking soda and vinegar solution doesn't take much time. Ideally, you want to repeat this process at least once a month or when your black water tank has reached capacity.

Not cleaning your tank regularly can lead to debris build-up and a terrible odor, making the cleaning process more intensive and time-consuming. 

Things You’ll Need

Here is what you’ll need:

  • 2 cups white vinegar (white vinegar is best as it’s known to kill bacteria)
  • 1 cup baking soda
  • A gallon warm water (above 130℉ to kill bacteria)

You'll also need the following handy tools to make your cleaning solution:

Step 1: Safety First

Before you empty your black tank's contents, ensure you're protected from harmful bacteria or fumes (you’re dealing with sewage, after all). Put on a pair of good-quality gloves to protect your skin.

Wearing a face mask can also help you better cope with the tank’s unpleasant fumes.

Remember, the longer you leave a tank unwashed, the more fumes and residue build up.

Step 2: Dump the Sewage at a Designated Dumping Station

Connect your sewer hose to the black tank with a clear elbow attachment. The sewer hose is then connected to the sewer, and you can open the tank's gate valve.

Once the liquid stops flowing (you'll be able to see that no more liquid is flowing through the clear hose elbow), you can close the gate valve.

Step 3: Flush the Black Water Tank with Water

Next, you want to flush out your tank to remove any loose debris and build-up. Fill your tank with clear water and open the gate valve once more. Allow the tank to drain completely.

I like to flush my tank at least three times before I add the vinegar and baking soda mixture. Once your tank has drained entirely for the third time, close the gate valve. 

Ensure it's tightly closed to avoid any unwanted leaks.

Step 4: Prepare the Baking Soda and Vinegar Mixture

Now that your black water tank is empty, pour two cups of white vinegar directly into the tank.

Now, add a cup of baking soda into the tank and give the mixture a good stir with either wooden spoon or stick or close the lid and slosh it around to activate the chemical reaction.

The mixture will start to bubble as the two ingredients combine.

Then add warm or hot water to the tank to fill it up and let it soak.

You can also pre-make the mixture before pouring it into the tank

  • Grab a large bucket and fill it with a gallon of warm water at higher than 130℉/55ºC to eliminate bacteria.
  • Add two cups of white vinegar to the water. When mixed with warm water, vinegar also kills E. coli and Salmonella.
  • Now, add one cup of baking soda to your vinegar mixture. Stir the liquid generously with a wooden spoon. Don’t worry when the water begins to bubble; it’s simply a reaction as the vinegar and baking soda combine.

These two ingredients together make a powerful team. Vinegar is acidic and helps break down the calcium and mineral build-up in your tank, while baking soda dissolves any dirt or grease in the tank. 

Step 5: Add Your Mixture to the Tank

There are two ways to add the baking soda and vinegar mixture to your black water tank, and both are effective. 

Option 1: Pour the mixture directly into your tank and let it stand for around 20 minutes. You can leave it for longer and even overnight for even more effective odor removal.

Option 2: Pour the mixture into your toilet and flush it. The mixture will clean your toilet and the pipe leading to your black water tank. Then allow it to sit for at least 20 minutes or longer.

I’ve used both methods for adding my cleaning mix to the black tank, but I prefer pouring the mixture directly into the toilet as I know the entire system gets a good clean.

Step 6: Do a Final Rinse (Optional) 

You can repeat this process (mixing the warm water, vinegar, and baking soda solution and flushing the tank) for a final rinse. 

I like adding an extra cup of vinegar to my final rinse to neutralize any unpleasant odors. It works like a charm. 

Step 7: Finishing Up

Once you’ve flushed the black tank, dump the mixture through the sewer hose into the sewer. 

Disconnect your sewer hose and elbow adapter, and then seal the gate valve tightly.

Last but not least, ensure you fill your tank with about ⅓ of tap water to avoid any build-up of paper or waste.