Get Free Shipping On All Orders Over $30

Learn More

Deep Cleaning RV Holding Tanks

July 14, 2020

Deep Cleaning RV Holding Tanks - Unique Camping + Marine Guide

View Printer Friendly Version

Here at Unique Camping + Marine, we get a lot of questions about how to clean RV holding tanks. Maybe you have a clogged toilet, in which case our guide, Unclogging an RV Toilet, can help you get back on track!

Maybe you aren't dealing with a clog (or any specific problem), but you just want to perform a routine deep clean on your holding tanks to make sure you're staying in front of any potential issues.

Well, we’ve got you covered! Cleaning RV holding tanks is a simple and easy process for both black and gray tanks, especially when using Unique Camping + Marine products. Today we’ll outline exactly how to deep clean your RV black and gray tanks!

The Unique Method

Before we jump into how to deep clean your black and gray tanks, however, we want to make it clear that simply deep cleaning your RV holding tanks semi-frequently isn’t enough to make sure that you don’t run into issues like clogs, pyramid plugs, or nose-wrinkling odors. In fact, you need to make sure that you’re putting the right habits and preventative care measures into place on a day-to-day basis to ensure that you never have to deal with time-consuming and costly issues again.

This is where The Unique Method comes into the picture! As the name suggests, this is our proven, all-encompassing guide for properly caring for your holding tanks - both black and gray. Thousands of RVers already trust The Unique Method every time they hit the road. If you’re tired of never-ending tank clogs or pesky odors, The Unique Method will be perfect for you!

Deep Cleaning An RV Black Tank

Deep cleaning your RV black tank is simple! Unique Tank Cleaner will usually deep clean a black tank in about 12 hours (overnight while you sleep!).

Here’s the easy steps:

  2. Fill your tank with water. This might sound obvious, but you can only clean what the water is touching. So, the more water you add, the better Tank Cleaner will work.
  3. Dump 1 entire bottle of Tank Cleaner into your black tank by pouring it through your toilet.
  4. Let Tank Cleaner work for 12-72 hours. While Tank Cleaner typically works in about 12 hours, the longer you let it work the better! (The is no amount of time that is too long to let Tank Cleaner work. It won't cause any damage to your RV if you let it sit for days, weeks, or even months!)
  5. After you’ve allowed Tank Cleaner enough time to break down all the solids and residue inside your tank, open up your black tank valve and dump the tank.
  6. If your RV comes with a built-in tank rinser (or “flusher”), it’s a good idea to run it for about 30 minutes or until the tank is thoroughly rinsed out. If you don't have a built in rinser, we recommend using a wand or external tank rinser that connects to your discharge line.
  7. CLOSE YOUR BLACK TANK VALVE. Always keep your black tank valve closed unless you’re dumping!
  8. Enjoy the odorless functionality of a deep-cleaned black tank!

In general, it’s a good idea to perform a deep clean on your black tank twice per year - once at the beginning of the RVing season and once at the end. Our already-assembled Biannual Tank Maintenance Pack includes everything you’ll need to deep clean your tank twice a year! If your RV is stationary and rarely moves, it's a good idea to perform a deep clean like this every 60 days as waste tends to accumulate in these units because the waste never/rarely sloshes around.

Guide Continued Below

sign up and save. We send out frequent discounts and promotions.

Sign Up + Save

Join our newsletter and save $5 on your next order! Plus, get exclusive members-only discounts, access to our library of downloadable guides, and insider information on new products and promotions.

Learn More

Deep Cleaning An RV Gray Tank

Cleaning RV holding tanks is even easier when it comes to your gray tank! Oftentimes, your gray tank can start to stink as soap scum, food grease, lotions, or other items (even stuff like human hair from your shower!) slowly build up inside your gray tank. This can cause a whole host of issues, including unpleasant sulphur odors and misreading sensors! But thankfully, because there aren’t a lot of solids inside your gray tank (at least, there shouldn’t be!), restoring your gray tank through deep cleaning is very easy to do. Essentially, all you have to do is remove the grease that has built up inside the tank!

From our experience with customers, the best product out there for doing this is Blue Dawn Ultra Dish Soap. Yeah, we know; at first glance, it doesn’t seem to make sense to add more soap to a gray tank that is already coated in soap scum! But, in reality, tons of RVers use Blue Dawn Dish Soap to clean their gray tanks, because it’s an awesome grease eater. It doesn’t leave a residue layer like other soaps, and it’s a completely safe product.

Here’s the steps you’ll need to follow:

  1. Close your gray tank valve before you turn in for the night. 
  2. Fill your gray tank all the way to the top with fresh water. The ultimate goal here is for water to cover all the areas that you want cleaned. If your tank isn’t totally full, only part of the tank will be cleaned. This is especially important if you’re looking to restore your gray tank sensors. You’ll want water to reach to the level of the highest sensor in your gray tank!
  3. Pour 20+ ounces of Blue Dawn Dish Soap down your RV’s kitchen sink. It’s possible that you’ll see it foaming back out of your sink or shower lines. Don’t worry! This is actually a good sign. It means that the grease-eating dish soap is spreading throughout your RV’s pipes and cleaning out all the built-up residue. 
  4. Let Blue Dawn work overnight. 
  5. Open your gray tank valve in the morning and empty your gray tank. It’s very likely that you’ll see a grayish/white residue on the bottom of your holding tank discharge pipe. This is literally the grease that was previously clinging to the inside walls of your holding tank! (Yuck!)
  6. Rinse your tank very well by filling it completely and dumping it several times.
  7. Repeat these steps if necessary. Sometimes it can take several cleanings before the gray tank is completely spotless inside.

Like black tanks, it’s a good idea to deep clean your gray tanks biannually if you are a full-hookup camper. If you are a boondocker (dry camper) we recommend you perform a deep clean like this on the last night of every camping trip to avoid grease buildup inside your gray tank.

Routine cleaning will help you stay on top of any grease buildup that can cause your tank to smell or your sensors to misread.

If your sensors are currently misreading and you’re in need of specific guidance for restoring your gray tank sensors, the steps given above are a great place to start, but for some more pointed information and procedures, please see our guide to Cleaning and Restoring Gray Tank Sensors by touching or clicking here!


At the end of the day, deep cleaning both your black and gray tanks will not only help you enjoy your RVing adventure all the more without having to deal with nasty odors or the increased potential for clogs, but it will also help your wastewater systems to run optimally for years to come!

As mentioned above, we at Unique Camping + Marine believe that implementing the right maintenance habits and preventative care procedures is the absolute best way to make sure that all your RV trips go as smoothly as possible. This is why following The Unique Method is so important! The Unique Method is designed for all RVers, and it’s hands down the most effective and easiest way to treat your holding tanks. The Unique Method is a proven way to prevent odors, beat clogs and pyramid plugs before they cause issues, and maintain working sensor gauges - all without one ounce of caustic chemicals! Beyond performing deep cleans of your black and gray tanks, The Unique Method will also help you in the day-to-day of RVing, allowing you to focus more on why you went RVing in the first place: to kick back and relax!

If you need more help with anything covered in this guide, or simply have a comment, please don’t hesitate to reach out to us at We’re here to help you anytime!

Also in Guides and Resources

What is the best RV Holding Tank Treatment? What is the better difference between rv toilet chemicals. Learn more.
Choosing The Best RV Holding Tank Treatment

November 25, 2020

There are dozens and dozens of RV holding tank treatments out there, and it can be overwhelming when it comes to knowing which one is the best for you. All of them claim to work miracles, but which treatment types are proven to work the best? 


Continue Reading

You Should Use Safe Products in Your RV Holding Tanks. Unique Camping + Marine
Why You Should Use Safe Products in Your RV Holding Tanks

October 07, 2020

Traditional, “old-school” RVing advice has often promoted information and RV maintenance products that are ineffective, and more importantly, can be harmful to your health. But with the advent of new research into the topic, many RVers have started to realize that a lot of the RV products on the shelves today are either really bad at their job, or even worse, dangerous. 

Continue Reading

You Need To Perform an RV Holding Tank Flush. Unique Camping + Marine
You Need To Perform an RV Holding Tank Flush

October 07, 2020

Many people may wonder, “Is a tank flush really that necessary?”. We recommend that you thoroughly flush out your black water holding tank for 20-30 minutes every 3-5 dumps. 

Continue Reading