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No More Guessing About Tank Levels! Gray Tank & Sensor Cleaning

No More Guessing About Tank Levels! Gray Tank & Sensor Cleaning

Besides water, an RV gray tank (or “grey” if you trend more British) takes in lots of greasy, sticky substances. These include food particles & residue from preparing meals and washing dishes, soap, shampoo, toothpaste & even body oils. After a while, it can gum up your holding tank sensors, causing a false reading on your tank monitors.

Cleaning out the gray tank and sensors is a really simple task, since there’s a readily available liquid designed to break up all of the crud that can build up in the tank: automatic dishwasher detergent. The gel type is easy to flush down the drain, and goes right to work breaking down and dislodging greasy build-up.

To calibrate the holding tank monitors in your RV, follow the steps outlined in our video:

To clean your gray tank, simply choose a day when you’re about to take a long road trip to a full hook-up RV park. Just start with about a half-full gray tank, pour about one cup of automatic dishwashing detergent gel (NOT standard dishwashing soap like Dawn or Palmolive… you DON’T want something that’s going to suds up!) into one of the sinks, and wash it down the drain with plenty of hot water. Then spend a few hours on the road, allowing the sloshing action in the tank to work with the detergent to break up any nasty gunk that’s accumulated. The longer and twistier the road the better, but a few hours of agitation should be plenty.

Once you arrive at your full hook-up campground (a dump station will of course work fine as well), simply pull the gray valve and dump the tank. All of the greasy gunk that was stuck to the tank will get flushed out with the water.

If your “3/4” or “full” light is the one staying on, start your trip with a fuller tank, which will ensure good water agitation on that sensor. But since the heaviest buildup is generally in the lower part of the tank, 1/2 tank or so should provide a good combination of water and empty space for strong agitation and sloshing as you drive.

If the first try doesn’t clear up the problem, just try it again on your next long road trip. It’s so easy and inexpensive that another attempt is no big deal. Once your tank is clean, your sensors should work fine and any odors you may have been experiencing should be eliminated or reduced as well (yes, gray tanks can smell too).


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Midnigh

Saturday 12th of February 2022

The Happy Camper Extreme cleaner is pure TSP, trisodium phosphate. This product is very harmful to humans and extremely harmful to the environment. When washed into water sources (lakes, rivers, ocean) it causes horrible algae blooms that choke out other natural inhabitants. Best to find another alternative!

AP

Wednesday 30th of September 2020

Thank you very much!!!

AP

Wednesday 30th of September 2020

Will this also work on black tank sensors?

TheRVgeeks

Wednesday 30th of September 2020

Hi AP! Absolutely! Because the black tank tends to be a bit messier than the gray, it can take more than one treatment to get them working 100%, but since it's pretty easy to do, it's not too much of a hassle.

Du & Nica

Saturday 12th of September 2020

Howdy! Great article, thanks for publishing it! One question: I can't find the one you used (Kirkland) nowhere nearby. The most similar I could find is this one: https://amzn.to/35x4F5S do you know whether it's safe to use and would work? I'm worried because I compared the compositions and the Cascade one has chorine bleach and cautic soda, not sure whether it would be safe to use in an RV tank...

TheRVgeeks

Saturday 12th of September 2020

We'd bet that the Cascade formula is almost identical to the Kirkland brand (Costco likely gets their dishwasher detergent from them, anyway). The concentration of the components of the detergent, when diluted in the contents of your tank, shouldn't pose any problems. The "caustic soda" is a big part of what's helping to break down the fatty deposits and other "gunk" on the tank walls, helping to clean the tank sensors off.

Du & Nica

Saturday 12th of September 2020

Howdy! Great article, thanks for publishing it! One question: I can't find the one you used (Kirkland) nowhere nearby. The most similar I could find is this one: https://amzn.to/35x4F5S do you know whether it's safe to use and would work? I'm worried because I compared the compositions and the Cascade one has chorine bleach and cautic soda, not sure whether it would be safe to use in an RV tank...

TheRVgeeks

Saturday 12th of September 2020

We'd bet that the Cascade formula is almost identical to the Kirkland brand (Costco likely gets their dishwasher detergent from them, anyway). The concentration of the components of the detergent, when diluted in the contents of your tank, shouldn't pose any problems. The "caustic soda" is a big part of what's helping to break down the fatty deposits and other "gunk" on the tank walls, helping to clean the tank sensors off.

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