Clearing a Clogged RV Black Tank: Another Viewpoint

Clearing a Clogged RV Black Tank: Another Viewpoint

Last updated on April 18th, 2015 at 03:44 pm

As I said in my previous post this topic usually generates lost of comments.  The comment below come form friend and fellow RVer.  Since his comments are extensive I thought they warranted there own post.:

While I never use chemicals, I’ve never said it would not work.  I just think there are better ways.  On the down side, cleaning with chemicals is very slow and expensive.  It will take several to many applications.

I am a more pro-active person.  When I have a problem, I solve it.  While I have never had this problem due to my actions, I once bought an RV that did and I have helped several people who had this problem.  I solve the problem this way:

  1. My first consideration is, how much time do I have?  If the RV is parked for several weeks you can attack the problem in stages.  If they are living in it, can they use the camp facilities?
  2. Next in importance, is the RV hooked up to a sewer system?  It is impossible to clean the RV’s black tank if it is not hooked up to a sewer.
  3. Will water drain freely from the tank, or has the pyramid covered the drain?  As long as I can get a trickle of water I know I can attack the problem with water.  If the drain is plugged, you have to be very careful not to over fill the black tank.
  4. If I have drainage and I have several weeks, I will put in a cup of Rid-X, fill the tank with water and let it sit for a week.  This will soften the mound and make it easier to chip away at.  I am not attempting to completely clear the tank here, but to make the mound more amenable to reduction.
  5. If I do not have drainage that becomes priority one.  In this case I go directly to work with a long toilet spray wand.  I must attain some drainage.  I jab the wand down into the mound as far as I can and then turn it on.  I use low pressure to prevent filling the tank.  Once I have a little drainage, I will work in stages, never letting the tank fill.
  6. If time is of the essence, I go right to work with the wand.  It never takes longer than a few hours, but it is hard work.  You are in and out of the RV, filling and draining the tank, opening and closing the valve.
  7. My favorite method is to put the spray wand into the top of the mound and then press down at an angle, then I turn the water on.  The easiest path for for the water is back up the hole created by the wand.  If you go straight down, the ugly water may spray back in your face.  I have plugged the hole in the bottom of the toilet with a rag to prevent spray-back.  I try to destroy the mound from the inside out.  The object is to saturate the mound with water to help soften it.  Just keep the wand moving.
  8. From here on it is just wand on, wand off, valve closed, valve open.  If I have time, I like to fill the tank and let it sit for several hours or overnight.
  9. When I think I am done, I fill the tank half way, put in ten pounds of crushed ice and go for a drive.  Then I fill and drain several more times.

As you suggested, I leave the black tank valve closed until it is around 3/4 full.  And, I always use Rid-X.  It generally takes me two weeks to fill that tank.  I use a variety of my black tank, camp facilities and facilities I come across during the day.  The Rid-X, for want of a better word, emulsifies the contents of the tank.  It is a simple bacteria that breaks down lumps and clumps.  If I were cleaning the tank more often than once a week, I would not bother with the Rid-X.  It works best when it has time.

Going forward I will not own an RV that does not have a built in tank spray system.  It really helps.  However, if you generally leave your black tank valve open, you will have a problem.

I hope this helps.


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43 Responses to "Clearing a Clogged RV Black Tank: Another Viewpoint"

  1. I recently had a blocage and was told to try 5 gallons of bleach dumped down the toilet and to wait 24 hours. the next day after pulling the valve the result a flush of clear water came forth and the clog was gone…

  2. While bleach will “oxidize” fecal matter, it will also kill the bacteria in a septic system. So, if the resultant material is to be dumped in a campground’s septic tank, the campground owner should discourage its use, especially five gallons at a time. Five gallons of bleach in a municipal sewage treatment system, however, is unlikely to cause an upset both because the treatment process is different and because the volume of materials is so large.

    When I used to own a campground, we cleaned a number of clogs with the pressure washer (and a full face shield – shower immediately after). Owning a campground wasn’t all glory.

  3. Linda Kalinowski · Edit

    A similar question is how do you clean the probes from a gray or black water tank to get an accurate reading of the tank level. We have tried products labelled to do just that with no success and are now in the process of filling tank and flushing extensively with a back flush of water.

  4. Even if you can get them reading properly, there just isn’t any way to keep the stock probes working for very long. There are aftermarket probes available that claim to work and looking at the design they may live up to the claim. They are called Horst Miracle Probes. If you try them please let me know how they worked for you.

  5. We have solved this issue altogether and for good without using harsh chemicals or wasting your time. See our web-site and learn for yourself why you don’t have to be concerned about black/gray tank issues any longer.

  6. I had two friends that had this problem in their fifth wheels. We were sitting in a park for six months. Both had clogged up toilets.
    I believe the problem was do to two things:
    1. Using 2 ply toilet paper, and the wife using lots of it.
    2. Not putting enough water in the tank after emptying it.
    3. Leaving the blackwater valve open.
    The fix. Use single ply paper. Scotts, 1000 sheet works just fine.
    Put at least five gallons in the tank after emptying it and keep the valve closed until it is full and ready to dump.
    Anybody who does not use a chemical that masks the odor when it is hot out most not have any friends.

  7. Does the RV toilet (I have a Thetford Aqua Magic 5 I think) drain pipe just go down and angle 90 degrees and drop into the black tank, or is there a vertical elbow or trap or something before it drops into tank? I am having drainage issues and I am using a flexible hose wand, but I can’t tell if the hose is going down and angling and right into the tank or thru another trap. I am concerned about damaging a seal if there is one down there, by ramming that wand down into it.

  8. Usually the toilet just dumps straight down into the black tank. The exception is on fifth wheels where the toilet is in the upper level. In this case there could be an angle in the drain for the toilet to the tank. If that’s the case it should be evident inside a storage compartment. You cannot damage anything with a toilet wand.

  9. We have a fifth wheel and the sewer was blocked a few weeks ago. We used a 3 ft snake and released the blockage. Now, for several weeks we’ve been going through the same thing. After we use the toilet a couple of times, the sewer blocks up to the toilet opening. We use the snake when it fills and when the snake reaches the 3ft mark down the hole, everything releases and all the material rushes down the pipe. Is this just a problem that can be fixed with hot water or do we need to replace pipes? Is there a trap that isn’t working correctly that we keep opeining with the snake? We have a new toilet purchased but don’t want to install it until we find out what the problem is. Please help. Thank you.

  10. Our fifth wheel plugged at the drain valve itself,sitting at a RV site for months. not wanting to move the trailer to a commercial dump station or risk a mess, I just ran a clothes hanger right thru the neck of the drain hose outside, taped over the hole and hanger where it entered the hose and used it as a small snake to go thru the plug from the outside in, taping over the hole and hanger worked as a seal preventing any mess and could still run the hanger in and out of the line. after emptying it I just trimmed the drain hose up an inch to get rid of the hole.

  11. We live in a 5th wheel trailer at an RV site. Our toilet clogs constantly. Even with the special TP. From what I’m reading, the problem is that we leave the valve open at all times. We thought the problem was the design of the trailer (It’s a grand junction). From what I’m reading I think we’re doing something wrong. Any tips you can provide for folks who live in their trailer long term? It’s a real problem. We use Magic Bullet to unclog but it’s once a week and I know there must be a better way to go about this. Thanks for any help!

  12. You’re right… the Black tank drain valve needs to remain closed until full. Also, once the tank is emptied and the valve closed again, you should add 2-3 gallons of water to the tank then use extra water when flushing solids.

    Learn more from these articles:

    RV Gray Water & Black Water Holding Tank Basics

    RV Waste Water System Care & Maintenance

  13. I just bought a 94 Jayco RK3050 5th wheel for full time living (first time owning a trailer), and noticed that the black water tank is not letting anything out. We used Ridx a week ago, and nothing is draining yet. The tank is 3/4 full and with the valve open, nothing happens. We are hooked into a septic tank and our grey water tanks drain fine, so the clog has to be either in the tank or at the valve. When I open/close the black water valve, it feels different than the 2 grey water valves. Seems “looser”, and other times, “harder” to open/close. My thoughts are that it might have broken off, and the valve isn’t opening at all. Any thoughts?

    Thanks, Scott

  14. Scott we have a 2011 Jayco Super light eagle and last year had a major clog. Turned out the handle came un screwed! Try screwing it back in. My problem is does righty tightly. Lefty lousy apply to these handles? I’m not sure. I worry all the time my husband might be un loosen it again. Our biggest problem is were not sure all the toilet paper is being flushed out and building up. We only use it for emergency bowel movements. Once you have it back up into the camper were afraid it will happen again. What a mess! We are still fairly New to a Fifth Wheel. Had a Pop-up before no toilet. He empties about every other Day. It has an outside hookup for a hose to flush it which helps! Do you think if we poured Hot water down it would help loosen any build up, Steve?

  15. If you are having problems with your Rv Toilet Cloged . The simplest and
    Fastest fix is to buy the Amazing New Twister . It’s a Rv Toilet Plunger it’s
    For sale on EBay. With a few simple Twist the
    Waste Pile is gone. Pile Moving Magic the Twister.

  16. I’ve been having some blockage issues with my black water tank draining. I’ve tried all the above except for the bleach because I heard it could damage your rv sewage system. a couple years ago I had a friend put Drano down my toilet which caused it to explode. So lesson learned and after replacing the black tank itself I find I still have issues regarding blockage. What is the best solution to digest tissue and solid inside

    black tank that won’t cost me a lot of money. Or is there somebody that can be recommended as far as a local mobile RV service handyman near everett WA that I can come to me if need be? I’ve looked online everywhere with only one person 100 miles away from where I am permanently parked.

  17. Having trouble with a blocked shower. We have tried everything but nothing seems to work Tried vinegar and baking soda. Tried hot water. Tried plunger Has any one got any ideas. We have a 1993 Kustom Koach fifth wheel

  18. Go to your local home store and get a drain snake. Get the one that looks like a mini plumber’s snake not the flat ‘tape’ kind. Get one at long enough to snake the whole line down to the holding tank. If you are lucky you should be able to get by with 25 feet. I’m stuck for a solution if that doesn’t clear clear the drain.

  19. First time Rver, rented a class A for a week some years ago. Not knowing any better, left the drains wide open all week. Just before leaving, toilet is plugged up. Not having any tools or supplies, solved the problem with gravity. Closed the drain valve and tied a rope to the sewer flex line, looping it snugly every foot or so. Ran the rope and the flex line straight up the side of the class A until the end was at the roof, about 12 feet high. Put my 12 year old son on the roof with the hose and slowly filled the flex line with water. 12 feet of water creates a reasonable amount of water pressure. quickly opening the drain valve forced the blockage out of the way. Stationed the wife by the toilet to watch for movement and quickly closed the drain valve before I created a massive overflow. Worked great and had an interesting story to share with the owner when I returned the RV.

  20. I’ve heard a lot of creative ways to unclog a black tank, but that’s a new one Tim. I am glad it worked for you but I have to admit I had visions of the Robin Williams movie RV while I was reading your comment. 😎

  21. Well I will start by saying this has been a great blog. I have had several issues through the years dealing with several RV Black water tanks stopping up on a variety of trailers I have owned. I currently have a 2013 montane 40ft 5th wheel II recently had a few extra visitors staying with me and went home for the holidays and a vacation. I told the one I left in charge not to do nothing but keep the trailer locked and adjust the thermastat as needed, well it seems like that just did not quite soak in. While I was home for Christmas the same people came to spend Christmas with my wife and I, while he was there he informed me he had drain the sewer and I told him that that was not what I had told him to do,I had told him I had drained every thing and he didn’t have to worry with it, well I returned to the trailer and went to work and completely forgot about it until a few days had past and decided I better drain it, when I went to drain the tank the first thing I noticed was the valve was cracked opened about an inch and when I opened in all the way only a little water came out, I have the clear fittings attached to the trailer on both ends of the sewer hose I can see if the water is draining and there was only a little. I used my trailer flush system to try and free it up but that did not work, so I called the person and he came to help me I ask him I noticed the paper I had in the trailer was gone and he informed me he had purchased some good toilet paper . I thought O that was really good and in a week you used 4 rolls of toilet paper and now there was only a little left on the current roll (Seriously!!!!!!) We then then ran the water hose in with the wand that did not work, then I took off the wand a ran the water hose as far down into the tank as I could. No surprise still only a little water. I then hooked up my spare hose to the fitting on the clear fitting and tried to back flush, that did not work, all the time I was doing that I was trying to close the valve and still the valve would not shut completely and there was still no water coming out, so I knew it was still plugged and all the water I was using would eventually fill the tank up and then there would be an issue for sure, I have had that happen once before and was lucky I finally busted it up by running the water hose up and down in the commode all the time I was looking at the water rising but it finally started draining. This time I was expecting that to happen so I was really making sure the water never rose up to the toilet. I even pulled the panels off in the storage compartment to look at the routing of the pipe and to see if anything could be done from that side and there was nothing that I could do so I removed the fitting and ran the hose straight into the the pipe this should be your last resort because that can get really ugly quit if it breaks loose but that didn’t happen I was luck but it was still clogged up and then there wasn’t even a trickle of water so I had pushed the clog in tighter. Now I was really starting to worry so I boiled water and poured four pots into the tank, still nothing. I bought a large bottle of Liquid Plumber and poured it all in. all the time not knowing if that would hurt the tank based on several things I have read but that was all I could do. Once I poured that chemical in the tank I boiled more water and pored it directly into the tank once again and let everything set for about an hour all the time I was checking to see if I had anything draining still nothing so I started running hot water in from my flush valve and started tapping on the line where the sewer hose connects to the sewer line and it finely started to trickle then it broke loose.
    Always keep your black water valve closed and keep water in the tank, when you dump it fill it up a few times and dump it again until you get clean water also put a clear fitting at the trailer the one that a water hose can be screwed to it ale add another one where the hose ties into the dump line in the ground. Use RV toilet paper,use a good order additive and everything should work out.One other thing to remember when your flushing with your flushing system do not forget to turn it off because the tank will eventually fill up and either come out the commode or blow a hole in the tank, I have seen both happen to people I have known. Sorry for the long story but this pretty much covered it all. Good Luck.

  22. We’re new to this RV life but just bought a 2012 Palomino Puma TT. Two bathrooms…yay! Yep 2 toilets to unclog!! Can someone explain why we are suppose to leave the black water tanks closed? We are permanently parked and connected to sewer. And should we also have the gray water tanks closed too?
    Think I’ll just buy a diaper genie and cheap baby wipes!
    Thank you!

  23. First, you need to use plenty of water when flushing the toilet.

    You need the liquid in the black tank to help flush the solids out of the tank and drain hose. If you leave the drain valve open, the liquids drain out leaving the solids in the tank. Over time the solids build up, usually right under the toilet, making it difficult to flush the toilet and clean the tank.

  24. *** Leaf Blowers just aren’t for Leaves***
    I had a clog that I could not get to dump,I was gonna get a snake after watching a u tube video.On the way to get a snake I had a light bulb go off and thought what if I got a leaf blower and stuck it up to the flexible outdoor line and cranked it up so I tried it to no avail..then I decided to go inside and run the nozzle of the blower right down the toilet hole 10 seconds later I had free flow !!! Problem Solved!!! Quick and Easy !!!

  25. What of the tank is completely full? Staying in a rental where the black tank was left open. The water seems to go at a slow trickle, but is completely full. What now?

  26. My tank was completely full so I waited for a time until the fluid drained down far enough to use the leaf blower. Of course, you want to turn off the water and make sure ther is no water left in the toilet (electricity and water don’t mix well). I have a heavy duty leaf blower. The upper end of the tube is fairly round and fit the opening pretty well. Worked great…Thanks Tim.

  27. Well I’m in a bind. I have a clog that will not bust. I’ve snaked it, I’ve shoved pipe down there in hopes to push something loose, I’ve run pipe down with water on only to have it back up into the camode. I’ve run pipe in from the drain side with water flowing, I’ve used a balloon to build pressure and blast the clog loose from the drain side, I’ve used chemicals now and tried boiling hot water. I can’t get anything. It was slowly draining down but now I think I’ve angered the clog and it won’t even drain anymore. So now here I am with a camode full of satans punch and it won’t go away. I’m going to try and build pressure on a line and run it down the camode and see if it will blast it out of there but I think I’m going to have to manually drain the camode. Cup and a bucket. I’m at my wits end. I Travle for work and so I live out of it full time. The piping 90s under the toilet into the tank. I can’t say for sure just how long the run is from the tank to the hole in my floor. Earlier my wife was pushing on the pex pipe and I could hear it scraping the tank but wasn’t getting any kind of drainage. Any help would be greatly appreciated at this point in feeling defeated and hopeless. Thank you.

  28. I have a black tank clog not sure where it is but im seasonal camper and pvc piped sewer from camper to sewer trying boiling water now somewhere a clog …. Husband is at work i dont know what to do any suggestions???

  29. Great suggestions everyone… I’ve gone back and forth trying to convince friends the proper way to use your tanks. First of all every camper has a tank. One of my buddies said his rv didn’t. Lol. So as long as we are on the same page about the design of these tanks it should be simple and self explanatory. Think of a long thin rectangle. At the toilet side of the tank there is an opening at the top of your tank that hooks up to your toilet. At the complete opposite side and at the bottom is a drain where your debris leaves and enters the sewer line. The pull handle is how you release the black water from the tank and the same thing for the grey water. ALWAYS KEEP YOUR BLACK TANK CLOSED WHEN CAMPING. NO MATTER HOW LONG YOU ALWAYS KEEP IT CLOSED UNTIL IT FILLS UP. When you start to notice your black tank is getting full…… Close your grey water tank. Don’t shake your head…. just do it…. you’ve has your grey water tank closed for a couple days now and your black water tank is ready to clean…… here we go…. release your black water…… (grey tank has a good amount of water in it by this time) after releasing all black water close the black water off and fill black water with hose or auto clean. Let get about full and turn water off. Release black water again…. do this one more time …….. or until all floaters have not visible. (You should always have a see through link at the end of your drain so you can see what your dealing with) lol. Black water is clean and at this time push lever in and close black tank. Now there is about 5 feet of black water debris that washed up the grey water tube when you released the black water…..this is why you now have grey water closed right now….. open grey water and look at what comes done. This is why you have ever a mess when you get done cleaning your tank and drive to your next spot and open your safety cap.

  30. So, how do we break down a hard mass of material clogging our black water tank? Can get liquid to flow & air from a leaf blower to blow through, but matter has already hardened.

  31. My husband and I live in our rv year round. We’ve ran into a serious issue. My husband left the black water valve open & now the tank is full of solids. How do we get the built up solids to drain out? We’ve tried running a hose down the tank. All that happened was the liquids drained out & the solids remained. We’ve even used a septic wand with good strong water pressure. Still the same results. The liquids drain & the solids remain. We’ve got to get this issue resolved. What can we do to get the tank to empty completely? Any ideas or suggestions would be very much appreciated.

  32. I have a Newmar Kountry Aire 5th wheel. where the holding tanks are located, the underbelly of my camper has began to “bow” and looks like it could bust open at any time! what can I do?

  33. Of course, you know what has to be done. There are four possible causes for what you describe, 1) the underbelly material is just sagging from age, 2) a holding tank has stretched and is sagging down on the underbelly, 2) a holding tank has come loose and is weiging down on the underbelly, 4) there a a leak in the plumbing and water and/or waste is sagging the underbelly. You will not know which until you investigate. If you do not feel qualified to do the work then it is time to see your trusted RV technition.

  34. I am very new to the whole RV life. We are living in our RV and went to dump the black tank for the first time. (We kepr the valve closed until itvwas fairly full) The fluids drained but the solids did not. I foolishly ran the black water flush and dlushed2 rhe toilet, now the tank is very full. So now we can’t use the wand is that correct? It seems like it’ll overkill. What do you suggest is our next move?

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