Thursday, June 1, 2023


Does using ice cubes to unclog a black tank work?

In this 3-minute video, technical advisor Dave Solberg discusses whether using ice cubes to clean and unclog level sensors in an RV’s black tank really works.

You hear it often—empty your RV’s sewer (black) tank, add some water, then drop in a bunch of ice cubes. Then drive around so they bang against the sides of the tank, unclogging them and helping your level gauges function again. Does this really work or is this just a bit of fiction that is passed along but never tested?

Dave also offers some tips about cleaning a tank in more conventional ways, using products like Tank Blaster.

If you have any experience using ice cubes to clean your RV’s holding tank, good or bad, please leave a comment.

More from Dave.


Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.


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William Rosar
1 month ago

We had a 1998 Thor, Millennium that never had this problem ever and I rarely flushedit. We now own a 2021 Forest River, Wolf Pup and from day one the black tank always registers 1/3 tank. They make these things so cheap anymore. I’ve heard of so many tires blowing out, even the spare that had never been used.

Bob M
1 month ago

Maybe we need a class action lawsuit against the RV manufactures and tank sensor manufacturers to resolve the issue. Then maybe they’ll design tank sensors that work.

Diane McGovern
1 month ago
Reply to  Bob M

Hmmm. Tank sensors that work. Now there’s an interesting concept. 🤔 Thanks, Bob. Have a good evening/night. 😀 –Diane at

Bob Weinfurt
1 month ago

I have a 44 year old motorhome. The gauges didn’t work when I bought it 8 years ago but fortunately I can look down the toilet to see the level in black tank. What I do near the end of every season is dump and fill the tank about 1/4 with water and dump in about 5 pounds of ice cubes then immediately take it for a ride for ten minutes or so. (Longer would be OK too.) More ice wouldn’t be able to move around to loosen any “yuk” that’s possibly sitting in a corner or on the bottom of the tank. I dump and flush the tank with 5 gallons of water. The gauge still doesn’t work but the bottom of the tank is clean.

Neal Davis
1 month ago

We bought our first RV after it had sat on the lot of two different Texas dealers for a total of 14 months. I suspected that the black tank had a thick hardened layer of “material” at the bottom. In any case the 40-gallon black tank always seemed to fill quickly, so I tried the ice cube cleanse. Perhaps I used too little ice, or perhaps it really is an unfounded RV legend. In any case I observed no change in our black tank after inserting 10 pounds of cube ice and driving for over an hour.

Last edited 1 month ago by Neal Davis
1 month ago

Tried dishwasher detergent (low suds) years ago with a half full tank of warm water. Drove around for 20 minutes then dumped it and it was improved on 2 of the 3 indicators. I guess thats a positive result.

Never tried the ice though, it always seemed a bit of an ‘old husband’s tail’.

The indicators in our newest rig, 2019, are working fine.

Last edited 1 month ago by Cancelproof
Wayne C
1 month ago

I’ve had good luck with garnet instruments’ SeeLevel system
I agree that after a person becomes familiar with their RV, you have a pretty good idea when to dump/ fill without tank sensors.

Larry H Lee
1 month ago

I have tried the ice cube cleanout system a few times with absolutely no benefit.
I have the usual GreenYellowRed indicator lights with in tank probes. So long as the red lights function I am “good to go”. That means about half the time I just have to guess when to dump in order to avoid any shower backup problems.

Capt. Jim
1 month ago

My current RV is 40 ft. 5th. wheel. we mostly stay in established campgrounds with full H/U. I never really look at the tank sensors as they mostly don’t work except, of course, the fresh water which seems just fine. Since we are hooked up, when I flush and get that burping noise, I hook up the tank flush hose, open the drain and let it go. I leave about 5 Gal. of water in the tank and it’s back to business. Where the ice comes in is when I return home. After prepping for storage, I put a 10 pound bag of ice down the toilet, 5+ gallons of water and 1/4 cup of detergent. I then drive 20 minutes to the free dump at the marina that also has fresh water for the flusher. I’ve had 7 years of trouble free operation. I realize this is slightly off-topic, but in my situation, the tank sensors don’t really matter. Just my .02.

1 month ago

Tried it all as a newbie. Now after emptying the black tank, I close the knife valve at the end of the discharge tube (that I put on a month after I bought the RV). Then open the gray and black tank valves for 30 seconds so that the gray water back flushes the black tank. Close the gray valves and open the knife valve. Black tank empties and it is amazing how well this works! Let it drain until it stops running and use the black tank flush water valve to flush out the bottom grime and then empty the rest of the gray water. 1/2 cup of Dawn detergent in the black tank with about 5 gallons of water and we are all good, except of course for the tank sensors which have not worked since the first tank dump three years ago! I agree with an earlier commenter that a new design for waste holding tanks is needed as the amount of freshwater used in RV black tanks is excessive.

1 month ago

While the commercial tank cleaners may work, another and cheaper alternative is using a 1/2 cup of liquid laundry detergent which will also clean the inside of the tank. A quarter tank of water and the laundry detergent will clean the side of the tank and probes. Empty the tank, put water and detergent in and drive to to the next stop and dump. The laundry detergent does not foam up like other types of liquid soap, so no problem with lots of suds.
You also don’t have to worry about dumping it into the sewer or septic system at the campground.

Jim Johnson
1 month ago

A number of commercial tank treatments also call for agitation to perform their ‘magic’. My general unscientific observation is the bigger the unit, the more likely it is to be in a stationary situation between dumps. Anybody sell a ‘Magic Fingers’ tank rumbler for tanks that don’t bounce down roads every couple days?

With all the gee-whiz improvements coming into RVs, I’d sure like to see the engineering staff come up with better waste systems for RVs while they are stationary. The current designs are decades old. Further, they use more water than any residential system to effectively clean those tanks. Not to mention ice cubes or magic elixirs.

Sandi Pearson
1 month ago

We have a standard routine of dump, rinse by filling and dumping, then adding our preferred additive. Mostly it works but we hit a snag that no cleaner, method, or ice could clear. Our sensors are probeless so a film must have developed on the wall. We finally bought a turbo wand that connects to a garden hose and used it. WOW it really does a great job! Our tank is right below the toilet so it’s an easy job. Been reading empty when dumped for 6 months…knock wood.

Bob p
1 month ago

There is a video on YouTube where the guy simulates sludge in a holding tank in the bed of his truck. Then putting 20 lbs of ice cubes in the tank goes for a drive. Basically the ice cubes float in the liquid and never get near the bottom where most of the sludge lays and never get around the senders enough to provide a scrubbing motion. He did this experiment several times using more ice and never did get the cleaning action claimed by various people repeating the rumor. So it is a campfire rumor!

1 month ago
Reply to  Bob p

Comes from The Fit RV- and it’s very entertaining. Everyone should watch it.

Gary W.
1 month ago
Reply to  Bob p

Bob, Jane posted the link 2 post above yours if anyone is interested

1 month ago

We’re fortunate. Our toilet sits directly over the black tank so we can actually see down there when the flapper opens. Probably a rare feature.

1 month ago

Ice cubes did not work; however, hot water does.

Tommy Molnar
1 month ago

Even if you somehow get the sensors to finally work using ‘whatever’, the minute you start actually using the tank again the sensors go to pot. You just have to get used to how much black tank space you use and know when you need to empty it. I know there are sensors out there that some RV’ers swear by (after market, of course) but I can’t remember those product’s names.

1 month ago
Reply to  Tommy Molnar

I 100% AGREE with you Tommy. It is our experience as well. In fact we laugh each time we dump. With each dump we clean to clear water. Our tanks sensors say 2/3, 1/2 1/8 fill & never ever 100% empty. We guess each time to make a game LOL. Happy Safe & Good Clean Black Travels!

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