How To Clean Your RV Holding Tank Sensors

Sometimes, even immediately after dumping your black tanks, the tank sensor panel can show that the black tank is full.

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Why does this happen to your RV Holding Tank Sensors?

This is because your RV Holding tank is connected to the motion sensor panel with the help of 4 screw probes, each of which adds to the sensor rates. In the due course of time, waste can accumulate around these connections and send the wrong signal to your panel.

Confusing as it may sound, this actually happens due to one or more obstruction in the black tank. The obstruction can be caused by sludge, slime or even solid particles.

According to Randall Murray,

“This is generally caused by a build up of waste materials or anything that might have made its way down the toilet. These items can block the sensors preventing the correct read out”.

Here are our best ways to clearing your RV Holding Tank Sensors ASAP:

  1. RV Swivel Stick: Use it to spray out any obstruction
  2. Hot Water treatment: Flush the tank with hot water
  3. Water Treatment: Fill your tank till the full and let it rest for 1-2 hours. Flush it off after!

Make sure to clean your holding tanks periodically and use only RV Tissues in the toilet.

Have you had any experience of the sensor panel of your RV Holding Tank Sensors acting weird right like above? What did you do then? Try this method the next time; do tell us about your experience in the comments below! 😀



  1. The only misleading comment is use only RV specific toilet paper. THAT is one of the biggest wastes of money any RVer can do. Regular single ply toilet paper that is septic tank safe will work just as well. Do the test. Two or three sheets of paper in a jar of water, shake it up and let it sit. Show me where the RV paper dissolves any better than regular paper !! Been using Scott single ply for years and have NEVER had a black tank issue !!

  2. I completely agree with Rob, 100%!!
    The cost of rv toilet paper is insane. I’ve always used single ply in all of my rv’s and I’ve never had an issue either.

  3. Also, Laudry soap and fabric softener break down toilet paper. I buy some at the dollar store that is both in one container. I use this to clean my toilet. And, my bathroom always smells good. It never smells like sewage. NOT even if someone leaves the lid up.

  4. I also agree there have been test made of the dissolving ability of different toilet papers and Scotts single ply rated right up there with any rv paper and it hold together to last until after your done wiping. Unlike rv toilet paper. To clean my sensors I have used the geo method for years. But don’t use it as a tank treatment like most do but as a cleaning solution. I pour a cup of bleach,laundry soap and calgon in my tank. Then fill it with water then let it sit for an hour or so this works great. Also if you get an issue with a poop pyramid or a buildup of solids in your tank I have been told by several rv repairmen to put Rid-ex in your tank and let it work. eventually it will dissolve the solids so they will flow out. You may have to take a hose to it to help break it up but they have said this works well.

  5. I use Charmin as recommended by Mr. Whiffle. Never any issue. The main point of black tank maintenance is water, lots of water and even if hooked up the parks sewer leave the black tank dump valve closed dumping as needed. Wash it regularly but use lots of water when flushing.

  6. Dawn and water softener and about 1/2 full, and drive between camping places letting it slosh around. This may take a few trips depending on the severity of buildup. I got water softener on line for a little of nothing. Now I use a product called Happy Campers which is just detergent and water softener in a little pail with a scoop. One scoop and about 5 gallons of water just after dumping, and no problems… I only flush about twice a year. Our camping season in Texas only lasts 364 days a year… Wifey won’t let me be gone for Christmas…

  7. I’ll add my 2 cents worth of experience here too….

    holding tank chemicals are unnecessary if not completely unnecessary. We stopped using chemicals a few years ago and have no ill effects, including odors.

    In my experience, if you dump your tanks (when theyre full or as full as possible before your departure) and rinse them using the tornado tank washer you’ll get the best results.

    And this guys proves it in his testing too –

  8. Empty a bag of ice into the toilet….drive around allowing it to move in the tank cleaning it prior to melting….flush tank.

  9. Fail safe method to clean the sensors is to dump your tank,close the dump valve and add 5 gallons of hot water with 1 or 2 cups of Dawn dish soap,drive to your next destination and all will be well!

    • I’ve done similar. 1/2 cup of dish soap w/2 – 3 gallons of water. Drive to next destination. Presto clean sensors.

  10. I use Angel Soft TP without problems.
    If you get “Turd Castles” ….you’ve probably left your Black tank open…not good. Keep it closed at sites, and let the water do its thing.
    I only use Dawn or Dollar Store equivalent for dishes and instead of chems.

    • Dawn dish soap has ammonia in it. Mixing ammonia and bleach together results in toxic fumes that are very dangerous and cause extreme irritation to the eyes and lungs and can even result in death. In fact this is the same chemical reaction that’s used to create Mustard Gas used in chemical warfare.

      • Is that really true, Chris? Why do they use Dawn on wildlife covered in oil? I bath my dog with Dawn, so does it really have ammonia?

  11. What if the sensor panel always shows “empty” when you know it is full or half full? The grey water, fresh water and battery are correct on the panel, but the black water reading always shows empty no matter what.

    • The sensor works on a low voltage currant passing through the water to the highest sensor that is below the water line. If it’s now reading either your sensor is coated with something to stop the currant or the wire is not transmitting either loose or broken

  12. I get the septic safe toilet paper at Dallor General. $1.00 for 4 rolls. Can’t beat that! Than I use the per-measure per-measured blue marine tank chemical. It works the best. I have tried many others n it just works better for break down n orders. When we dump, we fill the tank 2 to 3 times with that much water draining it flushes everything out n we have never had any issues with the sensors. We’ve done it that way for years n our tank flushes out clear.

  13. In my other camper I would drain the black tank, fill the toilet up full of water and flush with the dump valve open, I’d do it two times. Then close the valve and flush the toilet one more time and add a bag of ice. The ice will help clean the walls as it sloshes around on the trip home. It had worked very well for me in the past even on a short trip home, when I dumped the tank again, more came out and tank level went back to empty.

  14. I agree I use any toilet paper that states it sceptic tant safe. Also I installed a spinner on the side of my tank and when I dump my tank I connect the spinner to the water supply and that flushes the tank and cleans the sensor probes. It also helps break up any hard waste that did not flush out

  15. Wow. Some of you need to get spell check or review your post before posting. I had a hard time reading some.

  16. We NEVER have put toilet paper in our tank and it shows 3/4 full. We have filled it wit 3/4 water and dumped several bags of ice in the black tank and drive @ 200 miles and it still shows 3/4 full. We have also used 20 mule team Borax too. (Not sure a spelled that correct…spell check didn’t offer any suggestions)


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