Cleaning RV Holding Tank Sensors

Learn how to clean RV holding Tank sensors or misreading sensors
Learn how to clean RV holding Tank sensors or misreading sensors

Disclaimer: When talking about holding tanks and toilets in your RV, things can naturally get a little graphic. If you are looking for solutions to your odor problems, and you’re not turned off by these topics, this is the article for you!

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You’re Not Alone

Many RV owners struggle with sensor gauges that read incorrectly. It’s a very common problem. Without properly reading sensors it’s hard to know when your tanks are full so you can dump and care for your tanks properly. Unfortunately, many seasoned campers have resigned to the idea that sensors will always fail, so you can’t rely on them - you just have to know your routine and dump your tanks based off your routine usage.

But here’s the good news… In most cases, misreading sensors can be restored through thorough and proper cleaning.

In this article we will walk you through everything you need to know about your sensors:

  • Why your sensors are misreading
  • The difference between black and gray tank problems
  • Steps you can take to clean and restore your sensors
  • Preventative maintenance that will help ensure your sensors keep working properly

Let’s be clear about one thing, right off the bat: the best way to solve malfunctioning sensors is to avoid it completely. And the best way to avoid sensor issues is to follow The Unique Method.

Even still, sensors can misread even when it seems like we're doing everything right with our holding tanks. Don’t get down on yourself. It happens to the best of us! The good news is for the majority of RV owners this is a very fixable problem. So, let’s talk about fixing your misreading sensor probes!

Before We Get Started: It’s important to note right from the start that not all sensor issues are caused by an accumulation of poop and/or toilet paper residue that is stuck on your sensor probe. Though is the is case for the overwhelming majority of RVers, it is also possible that your RV’s sensors have simply reached the end of their lifespan. In other words, your sensors might just be broken. Unfortunately, no amount of cleaning will restore broken sensor gauges. You will simply have to replace them. So keep in mind that the following recommendations and tips are meant for people who still have working RV sensor gauges.


What Causes RV Holding Tank Sensors To Misread?

Before we talk about fixing your misreading sensors, let’s talk briefly about how we got here..

There are a few different reasons why your RV tank sensors might misread, but here’s the bottom line: tank sensors misread because something is covering the sensor. The debris coats your sensors in a layer of grime, causing the sensors to misread. Exactly what covers your sensors, however, varies between black tanks and gray tanks.

Gray Tank Sensors

You might be wondering what could possibly coat your sensors in your gray tank? There’s nothing solid like poop or paper in your gray tank, after all!

Well, not exactly. When it comes to your gray water holding tanks, solids are not the only things that can coat your sensors. In fact, food waste, grease, oil, and fats cause 90% of the sensor issues during normal use.

When we say “grease and oils” don’t think just bacon grease. Common, everyday-use items like soap and shampoo can also contribute to grease buildup on your tank walls and floors. As a matter of fact, it’s very common for soap scum and sludge to build up on the inside of your gray tank, coating sensors in a thick slime.

And by the way, this type of buildup can be extremely smelly as well! Not only do soaps and shampoos propagate foul smelling odors, but so do the food and food byproducts that make their way down your drains. We will get into preventative care a little later in this article, but for now just keep in mind that food alone can create some nasty smells and build up on the inside of your tank without proper care!

Black Tank Sensors

When it comes to your RV black water holding tank, the issue is a little more cut and dry. As you probably guessed, poop and toilet paper are the main causes of misreading sensors. As poop is broken down by bacteria and diluted into the liquids inside your tank, it can create a residue that cakes onto your sensors. (Gross, we know.) In the same way, toilet paper can also get caught on the sensors, especially if you use a lot or if you don't use a high-quality, bacteria-based waste-digesting holding tank treatment. All that being said, problematic sensors are not inevitable. In reality, if you use the proper care techniques, you can help to prevent misreading sensor problems in your RV’s holding tanks. Keep reading to the end of this article, and we’ll discuss this in detail!

Check your levels

Restoring Your Tank Sensors Requires More Than Just A Cleaning Product

Many people want a one-size-fits-all solution to misreading tank sensors. But the remedy is a little more nuanced than that. Before we talk about the steps required to solve your tank sensor issues, it’s important to note that restoring tank sensors properly and completely requires a combination of two crucial actions:

  1. Choosing the right cleaning products to effectively clean your sensor probes
  2. Performing the correct maintenance processes to help physically restore your sensors

Choosing The Right Products For Cleaning RV Sensors

Black Tank Sensor Cleaning Products

When it comes to cleaning the debris coating the sensor probes in your BLACK TANK, you don’t want to settle for underwhelming treatments that aren’t strong enough to get the job done. Truthfully, cleaning sensor probes isn’t complicated but it can be tough sometimes, and multiple treatments are required. Therefore, it’s important you start with a strong cleaner to minimize the amount of time and effort required to refresh your misreading sensors.

But a high-quality bacteria / enzyme treatment is not only safe, it’s hands down the most effective solution out there!

Out of the various bacteria / enzyme treatments on the market today, Unique Sensor Cleaner is by far the highest quality and most effective treatment. Here’s the reason: it’s packed with superior quality ingredients, specially formulated strains of the best bacteria, and the highest concentrations of active ingredients. Like we said above, cleaning your sensors is a tough job, so make sure you’re using the strongest, safest product on the market – Unique Sensor Cleaner!

If, while using Unique Sensor Cleaner, you still run into issues restoring your misreading sensors, please feel free to contact us here for assistance! Misreading sensors can be tricky, which is why we’re always here with you every step of the way to help you get the best results. 

Gray Tank Sensor Cleaning Products

When it comes to cleaning your GRAY TANK sensors, the right product for the job is good old Blue Dawn Dish Soap! Many people are confused by this, but it’s relatively simple:

Alternative Sensor Cleaning Methods

While a high-quality bacteria / enzyme treatment is the best way to put misreading sensor issues behind you once and for all, there are some alternative cleaning methods of which you should be aware. Two of the most common are:

  1. The Geo Method
  2. The Ice and Driving Technique

These are homemade solutions, and they are fairly popular in the RVing world. In fact, many people are familiar with them just from word of mouth. All the same, most frustrated RVers we talk to report that they've tried these techniques many times, and they simply don't work!

To find out more about the Geo Method, read our very in-depth article here!

Instructions For Cleaning Your Tank Sensors!

Now that we’ve covered the different types of products and/or alternative cleaning methods available, it’s time to walk through the steps necessary to fully restore your holding tank sensors!

Instructions For Black Tank Sensors

First, let’s get to work on your black tank sensors!This extensive article will walk you step by step through the process of restoring your black tank sensors. Customers who follow this guide consistently have great success restoring their holding tank gauges.

Instructions For Gray Tank Sensors

Next, let’s fully restore the sensors in your gray tank! In this article, you will learn how to use Sensor Cleaner to restore malfunctioning gray tank sensors. You'll probably be surprised how easy and inexpensive cleaning your gray tanks can be!

Sensor Cleaning Directions for Full Timers

Many of our customers are in fact full time campers, enjoying the off-the-grid lifestyle of year-round RV camping. But with full time camping can come some unique sensor issues. If you’re a full time camper experiencing sensor issues, we recommend filling your tank to the brim with water and adding one full bottle of Sensor Cleaner. You should allow Sensor Cleaner at least 72 hours to break down all the waste, grease, or toilet paper coating your sensors.

If for some reason you cannot completely fill your tank, you can fill the tank halfway with water, treat it with a bottle of Sensor Cleaner, and let the product clean your sensors for at least 72 hours while you continue using your toilet like normal. However, you should know that this is a less effective and less preferable method. The bacteria in Sensor Cleaner must physically touch all the areas in your tank that you want cleaned, otherwise these areas will remain dirty. Completely filling your tank with water will allow the bacteria to travel around your tank freely, reaching and cleaning all your sensors!

Help Is On The Way

If you are still having problems with your holding tank sensors even after you've followed the above-mentioned cleaning techniques, don't worry! We are always here to help you. Please feel free to contact our customer support team. Each sensor problem is slightly different, so it may take a little help from our experienced team to get you back on track!

Best Practices For Preventing Sensor Problems

Like we’ve said multiple times in this article, sensor issues can often seem overwhelming. Sometimes, these issues may not be fixed overnight, but there are certain steps you can take to prevent them in the future! We’ve talked to thousands of RVers (literally hundreds per month!), and from those conversations, we’ve developed a comprehensive, proven wastewater treatment guide called The Unique Method. The following points are taken from The Unique Method, and thousands of RVers have eliminated their sensor issues by following them!

Preventing Sensor Malfunction In Your Black Water Holding Tank:
  1. Always keep your black tank valve closed, unless you’re dumping your tank.
  2. Don’t allow caustic chemicals or antibacterial products into your black tank.
  3. Always treat your holding tanks with a high-quality bacteria + enzyme treatment each time you dump. We suggest Unique RV Digest-It.
  4. Never clean your toilets with chemicals or bleach. Use only RV toilet cleaners, like Unique RV Toilet Cleaner.
  5. Keep your tank temperatures below 85 degrees. If you believe the tank is exceeding 85 degrees, use more water with each flush and consider increasing the treatment dose.
  6. Use ample amounts of water each time you flush your toilet. Water is a huge component of proper tank maintenance and the majority of tank issues come from under-usage of water. We recommend holding down your flush pedal for ten full seconds each time you flush your toilet.
  7. Flush your holding tank for 20-30 minutes very often with a built-in tank-rinser, external tank-flusher, or wand. Ideally you should rinse your tank after each dump, but at minimum we recommend performing a deep rinse every 3-5 dumps
  8. Perform a deep clean on your black tank twice per year. Unique Tank Cleaner is specially designed for biannual tank treatments.

Read more about The Unique Method here

p trap for gray tanks
An example (above) of a "P-Trap" in your wasteline to create a barrier between your RV and sewer.

Preventing Sensor Malfunction In Your Gray Water Holding Tank:
  1. If you are camping on full hook-ups, leave your gray tank valve open with a P Trap in the line. This will ensure that grease naturally drains out with the water and doesn’t get stuck on the sensors or walls of your holding tank. Also, make sure you keep a P Trap in the hose so sewer gasses don’t seep into your RV!
  2. If you are dry camping, keep your gray tank valve closed and perform a deep clean on the tanks each time you use your RV. While dry camping, treating your gray tank with a high-quality, waste-digesting, toilet treatment can help you avoid accumulation of grease in your tank. We recommend using the Unique Dry Camper Camping Pack.
  3. Never allow food waste to get into your gray tank. Food waste contributes to residue buildup, grease, and nasty odors.
  4. Use a high-quality enzyme-based dish soap to wash your dishes. We recommend that you bypass the cheaper options and purchase a large bottle of Blue Dawn dish soap. Blue Dawn is a great grease-eater and will go a very long way in helping you avoid common gray tank issues!
  5. When possible, regularly back-flush your gray tank. We recommend flushing your tank for a full 20-30 minutes every 3 to 5 dumps

Answers To Common Questions:

How do RV tank sensors work?

  • In most cases, an RV tank sensor is mounted on the inside of your tank but some models are mounted on the exterior of the tank.
  • When the level of water in your tank reaches the sensor, it acts as a conductor, completing a circuit and letting you know that your tank is full.
  • However, waste buildup on the sensor can also act as a conductor, which completes the circuit and tells you your tank is full—even if it isn’t!

How often do you need to dump RV waste?

  • If you follow The Unique Method, we recommend that you dump your tanks every 3-5 days.
  • Dumping your tanks every 3-5 days will ensure optimum odor control.
  • If you must extend the period between dumps, make sure to treat your tanks with a high-quality bacteria + enzyme treatment, like RV Digest-It


Many RV holding tank treatments claim to solve your sensor problems, but, to put it plainly, they simply don’t. Though toilet treatment products are a very important part of maintaining working sensors, the majority of sensor issues come from how people maintain their wastewater systems, not the product itself.

The truth is, some products are much better than others, but no product is a magic bullet, so it's crucial that you use the right product and follow the right steps! We've outlined all this in The Unique Method, our comprehensive, proven guide to wastewater treatment in RVs. Without using the right treatment and performing the right maintenance process, it’s only a matter of time before you have a sensor misread. 

But as we’ve said, while cleaning RV holding tank sensors is often a complex issue, it’s definitely not impossible. In fact, if you use the right product and take the right preventative measures, holding tank sensor malfunctions can become a thing of the past!

Need Help?

Once again, when it comes to tank sensors, it’s impossible to cover every possible issue and its cause, which is why we would love to help you solve any further problems you might have. Please contact us if you have any questions or are dealing with an especially difficult problem. We would love to talk with you and help get you back on track!

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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