How To Clean and Restore Gray Tank Sensors In Your RV

June 12, 2020

How to clean and restore the sensor gauges probes in my RV gray holding tank

If you’re looking to clean and restore the sensor probes in your black tank, we encourage you to check out our guide to restoring your black tank sensors. Simply touch or click here! We have also written a very in depth article explaining the root cause of sensor failures and offering tips on how you can proactively prevent this problem in the future. You can read that article by touching or clicking here!

Key Points:

  1. Gray tank sensors stop working because food grease begins to build up on the sensor probes, causing them to misread. In order to stop sensor issues, then, you must get rid of this grease. 
  2. Blue Dawn Dish Soap is a great grease and grime digester. Follow the process outlined below to restore your misreading sensor gauges.
  3. The best way to prevent misreading sensors in the future is to follow The Unique Method, a proven wastewater treatment process that makes camping fun and easy. 

We hear from hundreds of RVers who have issues with misreading sensor gauges. In fact, this is a very common problem in RV holding tanks! Believe it or not, the cause of this problem, as well as the process for restoring your sensors, is different for black tanks and gray tanks.

So, in this article, we'll dive into the process for restoring specifically your gray tanks. 

So let’s jump in!

see if your gray tank sensors are misreading

Why Your Gray Tank Sensors Aren't Working Correctly

Before we get started on how to restore RV tank level monitors in your RV's gray tank, let's briefly discuss what is happening to make them malfunction.

Savvy RVers understand that solid waste shouldn’t be allowed to go down your drain lines and end up in your gray tank. Many of us scrape our plates before washing them and even have sink strainers to catch any residual waste before it rinses down the drain. But the fact is, even if you go to great lengths to make sure no food waste, grease, or debris ends up inside your gray tank, you’re still going to get some contaminants inside the tank. Unfortunately, this is simply inevitable.

You see, when you wash your dishes, pots, or pans (even though you have scraped them clean and maybe even wiped them), some residual food grease will get washed down the drain. And if you keep your gray tank valve in the closed position, over time this grease will build-up on your tank walls. Eventually, this can cause your tank level sensor probes to malfunction, causing them to read "full" all of the time. 

(Note: much to many peoples’ surprise, you actually may not need to keep your gray tank valve closed all the time. Touch or click here to read our article about the best gray tank practices for your specific type of camping!)

Besides food waste, soap and shampoo from washing will end up inside your gray tank as well, and it can also contribute to grease buildup inside your gray tanks.

So, at the end of the day, to restore your gray tanks, you must first remove this grease.

Restoring Your Gray Tank Sensors

Unlike black tanks, gray tank level monitors are actually pretty painless and inexpensive to restore. With black tanks, it’s normally toilet paper and poop that get stuck to your sensor probes, causing them to misread. This requires a strong bacteria/enzyme cleaner like Unique Sensor Cleaner to clean and restore the misreading gauges to their original condition.

But it’s not as difficult with gray tanks. After all, you aren’t dealing with solid human waste—only food grease and soap/shampoo residue. As we mentioned above, to restore your gray tanks, you’ll need to remove this grease. The best way to do this is to use a strong grease-digesting enzyme product. Lucky for you, the best one out there is quite inexpensive!

Many RVers are very familiar with Blue Dawn Dish Soap. It's a fantastic grease-eater, which is why it's regularly recommended for use in RVs. This is exactly what you'll need to restore your gray tank sensors.

Here are the steps you'll want to follow to fix the gray tank sensors in your RV:

  1. Before you go to bed, close your gray tank valve.
  2. Fill your tank with water. The goal is to use enough water to cover the highest misreading sensor. That way, you’ll be able to clean it.
  3. Pour 20+ ounces of Blue Dawn Dish Soap down your RV’s kitchen sink line. You may start to see it foaming back out of your sink or shower lines. That’s okay—and good! The grease-eating dish soap will spread all throughout your pipes to help clean out grease up and down your drain lines!
  4. Let this work overnight while you sleep.
  5. In the morning, open your gray tank valve and dump the tank. There's a very good chance you'll see a grayish/white residue on the bottom of your holding tank discharge pipe. This is the grease that was previously clinging to the inside walls of your holding tank! 
  6. Rinse your tank well by filling and dumping it several times.
  7. Repeat this process. It may take several applications to achieve completely restored sensors. In 99% of the cases, this will work, so just keep at it!

We normally recommend buying Blue Dawn Dish Soap in a large container like this one, so you can perform this cleaning several times.

It's really as simple as that!

Guide Continued Below

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Preventing Gray Tank Sensor Issues

Now that you've restored your gray tank level sensor probes, it's always wise to avoid it from happening again! The absolute best way to prevent future issues is to follow The Unique Method. The Unique Method is a proven system that will provide you all the tools you need to make sure your gray tank sensors always work properly! 

For people who camp on full hook-ups, this is easy! Just leave your gray tank valve open. This advice might seem contradictory to what you've learned in the past. But remember: it's the black tank that must always remain closed, not the gray tank. If you want to learn more about whether or not you should keep your RV holding tank valves open, touch or click here.

On the other hand, for people who dry camp, it's very important that you keep your gray tank valve closed, because open dumping is prohibited nearly everywhere. We recommend that dry campers use our Dry Camper Pack. This pack comes with all of the treatments necessary to keep your tanks clog-and-odor free. Plus, it includes a helpful guide on how to treat your tanks so you don't experience gray tank sensor problems!


We hope this article has helped you understand why your RV gray tank sensors are misreading and the easy process of restoring them!

Keep in mind that even the most proactive campers will occasionally run into sensor problems, so don't beat yourself up if your sensors start to give you trouble. Stock RV level monitors are pretty cheaply made, poorly constructed devices, so it's easy for them to fail. Luckily, restoring them is easy and inexpensive.

Most RVers can avoid this problem altogether by following The Unique Method. We’ve crafted The Unique Method from thousands of conversations with RVers just like you. It’s a proven method that works!

If, after following the process outlined in the guide, you’re still struggling with restoring your RV sensor probes, it's also possible that your RV level gauges are actually damaged and need to be replaced. In some cases, your sensors are simply broken. No amount of cleaning will restore these sensors.

If you have any questions, concerns, or comments, please feel free to reach out to us! Our customer support team is ready and willing to help you in any way we can!

Adopt The Unique Method

You bought your RV so you could enjoy life and spend time with family and friends. The last thing you want to do is waste precious time and money on fixing wastewater holding tank problems. Keeping your tanks in peak operating condition doesn’t have to be hard, confusing, or expensive if you follow our proven process: The Unique Method.

The Unique Method is a comprehensive tank care plan that we developed after years of conversations with real customers facing real problems. The Unique Method provides you with simple, preventative steps to stop odors, clogs, and sensor problems before they start so you can spend less time worrying about your holding tanks and more time enjoying the freedom and adventure of RVing. Try it yourself and see why thousands of campers trust their RVs with The Unique Method every day.

If you need more help with anything covered in this guide or simply have a comment, we’re here to help you anytime!

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