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How To Clean and Restore Gray Tank Sensors In Your RV

September 25, 2019

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

Misreading sensor gauges 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.

In this article we'll cover the process for restoring your gray tanks. If you want to clean and restore the sensor probes in your black tank, read this article.

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

finger showing RV holding tank sensors and gauges showing full levels.

Why Your Gray Tank Sensors Aren't Working Correctly

Though you may go to great lengths to make sure no food waste, grease, or debris ends up inside your gray tank, getting some contaminants inside your gray tank is simply inevitable. 

Savvy RVers understand that solid waste should never be allowed to go down your drain lines and end up in your gray tanks. 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.

Even with these precautions, debris will invariably make its way into your gray tanks and over time it can begin to foul up your sensor probes.

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

[Note: Much to your surprise you may NOT need to keep your gray tank valve closed all the time. Read this article to discover the best gray tank practices for your type of camping.]

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

To restore your gray tanks it's necessary that you remove this grease.


Restoring Your Gray Tank Sensors

Restoring your gray tank sensors is actually pretty painless and inexpensive. In the case of black tanks, the waste that gets stuck to your sensor probes, causing them to malfunction, is normally paper and human waste (poop). This requires a strong bacteria/enzyme cleaner like Unique Tank Cleaner to clean and restore the misreading gauges to their original condition.

To restore your gray tanks you need a strong grease-digesting enzyme and luckily the best one out there is quite inexpensive!

Many RVers are very familiar with blue Dawn Ultra Dish Soap. It's a great enzymatic 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 your gray tank sensors in your RV:

  1. Do this before you go to bed
  2. Close your gray tank valve
  3. Fill your tank with water (you have to have water as high as the highest misreading sensor to clean it!)
  4. Glug several ounces (like 20 or more) of the Dawn Dish Soap down your kitchen sink line. You may start to see it foaming back out of your sink or shower lines. This is okay - and good! The grease-eating enzymes will spread all throughout your pipes to help clean out grease up and down your drain lines!
  5. Let this work overnight while you sleep
  6. 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 inside your holding tank that is starting to flow out!
  7. Rinse your tank well by filling and dumping your tank a few times.
  8. Repeat this process. It may take several applications to achieve completely restored sensors but in 99% of the cases this will work, so just keep at it!

We normally recommend buying 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!


Preventing Gray Tank Sensor Issues

Now that you've restored your gray tank sensor probes it's wise to avoid it from happening again. The best and easiest way is to use The Unique Method for treating your holding tanks.

For people who camp on full hook-ups, this is easy! Just leave your gray tank valve open! This 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. Learn more about whether or not you should keep your RV holding tank valves open here.

For people who dry camp, it's a requirement that you keep your gray tank valve closed as open dumping is prohibited nearly everywhere. For you we recommend using our Dry Camper Pack. This pack comes with all of the treatments necessary to keep your tanks odor-free and clog-free plus a helpful guide on how to treat your tanks so you don't get gray tank sensor problems!

Sign up and get regular discounts on your favorite RV necessities. Unique Camping + Marine Holding Tank Treatments


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

Even the most proactive campers will occasionally run into this problem, so don't beat yourself up if your sensors start to give you trouble - even though you've done everything right! Sensor probes are pretty cheaply made, poorly constructed devices, so it's easy for them to fail. Luckily, restoring them is easy an inexpensive.

Most RVers can avoid this problem altogether by following The Unique Method. If you aren't familiar with this proven tank treatment process we highly recommend you learn more about it and build it into your holding tank habits!

If you are still struggling with restoring your sensor probes after using the process outlined in the guide it's also possible that your sensors are actually damaged and will need to be replaced. For some, no amount of cleaning will restore their sensors as they are actually broken, not just dirty.

Best of luck out there and please let us know if there is anything we can do to help! Our customer support team is ready and willing to help you in any way we can, so please feel free to reach out to us!

Happy Camping!

Unique Camping + Marine

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