RV Dump Setup

RV Tips – How to Dump the Black and Grey RV Tanks

When we purchased our first ‘real’ RV we were a little afraid of dumping the black and grey tanks.  We quickly learned the RV dumping process is easier and cleaner than we could have imagined…although it took some mistakes in the beginning to figure this all out!

Most new RV’s come with a free dump hose that looks like this:

crappy dump hose

The first thing you should do is find the nearest dumpster and throw this piece of junk sewer hose away! (Well technically you should purchase a new one before you throw the free one away) Why? The factory sewer hose (typically) doesn’t come with attachments and worst, it will only last a season or less, before springing a leak (or worse). A good hose is worth every penny (trust me from experience)!  Here are the 2 hoses we have owned and both have withstood the test of time and quality (you can purchase them directly from our awesome travel store):

  • RhinoFLEX 15′ Sewer Kit – I’ve been using this hose for the past year and I like the way it accordions down into such a small size.  I didn’t think the screw on removable bayonet would work well, but it hasn’t let me down yet.  If the hose lasts as long as our Smart Drain I’d say I like this one best.  Don’t forget to purchase the extension (RhinoFLEX 10′ Sewer Hose Extension), you want to have a minimum of 25 feet with you, plus if the main hose fails you can use the extension as your main hose till you can order a new one.
  • Thetford SmartDrain Sewer System – I have this hose still…after 3 years of full-time use!  The hose is just now beginning to have issues:  I had to order a new connector (SmartDrain RV Valve Adapter) which cost $13, but once I replaced it the fitting is just like new!  Can’t believe it.  I originally purchased the 15’ Smart Drain and the SmartHose 15′ Sewer Hose Extension.  (The only reason I purchased the Rhino hose was to test it out for comparison while I was waiting on the valve adapter to arrive)

RV Dump Setup

Here are the other items I use on a regular basis for dumping our RV tanks:

  • 45 degree Clear Sewer Hose Elbow so you can see what’s coming out: 45° Clearview Sewer Adapter 3″
  • A 50 foot water hose used exclusively for dumping the tanks (its not safe to use your drinking hose for this), we have an old hose but I would order this one now: Expandable Garden Hose
  • Gloves; I use disposable because the reusable type can get just as much bacteria as your sewer line after using a few times (I’ve had the same box for over 1 year).  Also make sure you purchase the gloves 1 size larger than you need, the larger size makes them easier to put on and take off: Nitrile Glove – Powder Free, Latex Free
  • Sewer Hose Support to help keep your drain off the ground and provide a downward slope for the liquids to travel down: Camco 15′ Sidewinder Plastic Sewer Hose Support

Purchase the sewer hose first, once you receive the hose then purchase a clear elbow.  Some RV’s need a straight clear piece, some are better with a 90 degree, or like on our Fleetwood a 45 degree was best.  It’s always a good idea to carry a back-up sewer hose, or an extra extension and fittings just in case; typically I am not one to recommend carrying extra junk but in this instance it’s not a bad idea because when you need to dump…you need to dump!

RV grey water dumping kit

I have just started testing a new makeshift dumping system for discrete use for releasing grey water during wild camping, or for emergency backup use at campgrounds.  I cannot officially recommend this as I’m still awaiting return emails from BLM and National Forest offices on the legality of grey water dumping.  So far the test has worked well, here’s the links for the items I purchased on Amazon to create this concept:


This is the “How To Dump” stuff I covered in the video

Put on your gloves and connect the sewer hose, make sure the connection is tight.  If necessary use a sewer hose support to get a natural slope to the sewer drain.

Lightly open the grey water tank by pulling the ‘grey’ handle.  Confirm there are no leaks and close the handle.

Pull the black handle firmly to open the black tank, let the tank drain completely.  With the black tank still open connect your sewer specific water hose to the Black tank flush.  Turn on the water and let the built in spray nozzle clear out any leftover waste in the tank, this will take 3-5 minutes, or until the water comes out mostly clear. 

This step is controversial so attempt at your own RISK: Push the black handle in and let the “Black Tank Flush” water spray for an additional 2-3 minutes, DO NOT LEAVE DURING THIS TIME or START ANOTHER PROJECT as you do not want to get distracted during this process.  Open the black valve again till the bulk of the water has come out, then repeat.  When the black tank is clean you should see mostly clear water coming out.  Turn off the water and close the black tank by pushing in the black handle.

Now pull the grey handle to empty the grey water tank.  Always dump grey water second to help flush out any waste that may be leftover from the black tank.

Once all the water has emptied push the grey handle to close the grey tank and remove the sewer hose.  Cap the sewer connector to keep any sewage from dripping into the bay. Add your favorite tank enzyme to the black tank after each dump, and add an enzyme to the grey tank every 4 dumps.

Rinse the sewer hose with water to remove any leftover sediment.  Disconnect the sewer hose from the sewer pipe and rinse.  Once the sewer hose is thoroughly rinsed spray the connectors with a disinfectant to kill any remaining bacteria, we use a vinegar and water mixture. Spray everything including the black and grey handles, the sewer line, the floor of the wet bay, the spigot where you connected your hose…etc.

If you have a composting toilet like us then you may want to consider combining the black and grey tanks, check out our ‘how to combine’ post here:

As you can see dumping the tanks is simple and only takes a few minutes to complete, the trick is knowing what not to do. There’s plenty of dump specific things to keep in mind like don’t drag the hose on the gravel when its full, don’t repeatedly step on the hose, and so on…but I have to leave a few mistakes for you to make on your own!

Share your dumping horror stories below in the comments. If it’s too embarrassing just use a pseudonym! Nothing beats potty talk, especially when it’s an RV (Robin Williams movie) style mistake…oh baby just let it all out! If you have any tried and true RV dumping tips feel free to share those as well.

Remember these are our recommendations from our personal experience, we can’t guarantee your success so make sure you read our disclaimer and do your own research. We have all the items listed in Our Travel Store if you want to purchase anything we’ve recommended, you pay the same and we get a few cents from Amazon.

Famous for my "how-not-to" videos, and typically the man behind the camera, sometimes I’m forced to be here in the “spotlight”. When you see my face you’re probably reading something more technical than adventurous, but either way I do my best to tell it like it is and infuse my opinions into the commentary…after all this is a blog and not MSN.

Comments (47)

  • George Aguirre

    I have a small camper trailer, we have had it a little more than 5 months and we haven’t taken it anywhere yet because I want to understand the whole hookup process completely, my main question is, after i am at my hookup site and i attach my water hose does the water fill up my toilet bowl automatically. I’m not sure i understand the toilet process. Please help! Thank you. Take care . GEORGE Aguirre.

  • Liz KS

    I have been living in my RV like a tiny house and keep my lines connected all the time. In the winter everything is insulated and wrapped up. To prevent problems with build up and toilet paper clogging risk I wash my dishes in a dish pan and then dump the gray water down the toilet. This is a great way to reuse the gray water and to rinse the black tank out daily.
    I am going to move my RV to another state and was just thinking maybe I should just throw out the hose and buy a new one instead of trying to clean it but maybe I will buy a regular hose and fill my tank up and flush it a couple of times like this post says and then inspect the sewer hose before deciding. It gets really gross when it is in use all the time. Would you use bleach or pine sol in solution when filling the tanks and leave for ten minutes then dump? I think this would be fine to do.

    • Curious Minion

      It’s a little more work, but to avoid buildup inside your hose and your black tank, leave your blackwater tank valve closed. When it’s getting toward full, close the valve to the greywater tank and let it fill up a little bit (one shower or a couple rounds of dishes). Then go outside, dump the black tank, and then rinse with the greywater. Then close the black tank valve & leave the grey open if you want. That way icky things don’t have time to dry out inside the hose or your black tank.

  • jerry

    Question- We have a spray system in our camper that is in some way connected to the gray and black water tanks for a better “clean out”. The dealership told us to hook up a hose and flush the system after we have dumped the black and the gray as to rinse the tanks. This is my question: is it necessary to do this? We have been doing this process since day one. Here is the rest of my concern: we have been hooking one of our clean water hoses to this. Is there a chance that we have a contaminated hose? Another thought along this line is that we have seen many people use the potable water connection and attach it to their clean out system because the clean out connection is not capable of having a hose hooked to it. Is there contamination of the potable water for the campground?

  • D. Kennedy

    Quick question, my husband and I are new at this and seem to have lots of issues with our new RV that we’re working with the dealer to get fixed under the warranties. Our most recent issue…we hooked up the hose to the outside flush connection, opened the black water valve and turned on the water. Instead to the water going into the tank it went into our cabin and flooded. We read the I manual and can’t find that we did anything wrong. Can y shed any light?

  • Audrey Maclure

    Have you ever heard of the sewer opening up on it’s own and dumping the contents on your camp site. We have a new Fleetwood Excursion (2016), used it twice and it dumped it self out on the second morning. The dealer says they can’t find anything wrong. Any advice?

    • Sam

      Sounds like a case of the “nearby children with nothing better to do”.

  • Christie

    Did you ever try the Sewer Cap with Hose Connection you mentioned? I’m starting with a composting toilet and am planning to use that method of emptying the grey tank.

    • We have tried it when we stayed on a few farms that allowed us to sprinkle and it worked great!

  • Ski

    We just purchased our first used RV. Everything was fine until we did the first “tank dump”. We followed instructions, precisely. We could see the waste being emptied through the hose, seemed everything was going well. Until we checked the toilet. There was still waste water about 6 inches below the toilet bowl, inside the tank. We followed the dump process 3 times, with the same results. What are we doing wrong? Frustrated.

  • Pete Halsted

    Here is another tip for those of you with a regular RV Toilet and Black Water tank. No matter how much you flush the tanks eventually stuff gets built up in them. What we did, with our old RV that didn’t have a composter, is every once in a while after flushing, and knowing we were in for a full day of travelling, we would dump a bag of ice into the black water tank via the toilet. As another poster mentioned you should add a few gallons of water in you black tank to keep from having to much “dry” stuff in it when you first use it. So we would put a few gallons of water in the black tank and then slowing dump the ice into the commode with the “flush value” open so the ice would go in the black water tank. After driving a few hundred miles the ice sloshing around with the water did a great job of scrubbing the inside of the tank, and of course had melted into just plain water by the time we camped for the night.

    We did this a few times a year, and it definitely keep our tank monitor clean and accurate as oppose to many of my RVer friend who’s black water monitor always report 3/4 or full.

  • Sandy Dechert

    Run hose water into toilet to clean the black tank after flushing.

  • Sandy Dechert

    Can also clean black tank after flushing by hosing through toilet?

  • Steve-O

    One just needs to be careful not to fill the black tank while rinsing. I always leave a few gallons of water in the tank when dry camping in order to avoid dry waste in the tank. I’ve seen this happen many times with new RVers who complain that the toilet won’t flush. It won’t because they have built a “pyramid of poo” in the tank. I can easily rinse my sewer hose with my water hose by being careful. I work at an rv park during the summer and see a few humorous dumping incidents every year. Unfortunately I usually have to clean up the mess after I get done laughing.

  • K.M. Morey

    I am so very thankful for your excellent tanks-dumping video. I wish I had room for a composting toilet, but in my 26′ Class C, I’m just glad to have the Thetford marine/RV toilet.

    I bought through your site and Amazon all the sewage-dumping items you recommend, including the gloves, plus other stuff through your site, and today, my SECOND attempt at dumping went so much more smoothly than the first, which was fraught with my nerves, the previous owner’s aged equipment, and amazing inexperience on my part! I queued up your video, watched each step and then paused the video, performed the step “in the flesh,” and then went back to watch the next step (tapping the trackpad with my gloved knuckle, not my hose-handling fingertips).

    Now I think I shall run through the park yelling, “I JUST DUMPED MY HOLDING TANKS WITH THE HELP OF THE WYNNS!!!!”

    What a gift your videos and your site are! A thousand thanks! (Yes, I have used the Tip Jar.)

    • Ha ha, I love it! So glad to hear you found this helpful and thanks so much for letting us know. It’s comments like this that keep us chugging along, making videos and sharing. You made our day, so thanks!

      • DC

        Question–what is the controversy about whether to close the valve after emptying the black water and letting the water spray in to fill it up some? In our old camper, we did that and were shown that by the dealer. Our current camper (2010) has a specific warning to never run the flush while the valve is closed. I haven’t done it because I am afraid I will damage something, but being sure it was clean was so much easier with the old camper and rinsing it with the valve closed. Thanks for taking the time to share your knowledge!

  • Learning Lesson # 243: We are coming up to our 1 year anniversary of being full timers, in fact we didn’t have ANY RV experience before we started full timing. I had a general idea about how to dump and luckily in that time frame we’ve only had 1 disaster. It was sort of like a cartoon where the hose keeps flying around all over, although not as extreme. It just seems extreme when you are dealing with waste rather than water. I didn’t have a weight on the connection to the ground and it popped up when I pulled the lever and started spewing all over the place. Good thing our RV has an outdoor shower….

  • Kevin

    When the waste hose is slightly twisted the dump end may twist out of the ground drain pipe and spill waste. It has happened to me. I purchased a threaded dump connection to drain pipes to prevent this, but not all waste connections provide threads . A weight on the dump end can prevent this.

  • Cindy B

    You two are awesome! I have a dilemma… just bought a Prowler TT. I plan to go composting in a few months. I am full-timing in CO (15 degrees, and 3 ft of snow) My valves are always frozen shut. I believe I have treated the tanks correctly with antifreeze and tank treatment. I have heard of using a hair dryer, but would need to shovel several hours to get power out there. Hand warmers on the valves?

  • patty lile

    help dont know what to do gray and black tanks both filled with poop. yep we bought it used and didnt know to check the valves. both were open 24/7. if you close the black tank valve it backs uo the drains into shower and sink any suggestions would be appreciated

  • chas steiner

    want a horror story..I had just dumped my sewage holding tank 4 days ago….we ere sitting in the camper eating lunch when all of a sudden there was a loud BOOM and the trailer rocked like someone ran into with something….went outside to find the sewage holding tank EXPLODED !!!!
    Wondering what would have caused that considering the tank probably only had 10 gallons of waste in it

    • Kevin

      Tanks have a roof vent for pressure variations, perhaps your roof vent was sealed somehow.

  • Gary

    So there I was preparing to evacuate the holding tanks of our travel trailer. We’ve had the trailer for several years so it’s not that I wasn’t firmilier with the process. My sister and brother in law were at the dump station next to us. I was visiting with my sister as I prepared for the task at hand. I reached under the trailer grabbed the holding tank twist lock cap. It had a tenancy to kind stick now and then so I put some pressure on it and she came lose, I looked down at the pipe and noticed a LOT of materiel coming out. It took me a second to get my mind around what was going on. I grabbed the flex hose and stuck it up under the drain and somehow realized the wastegate was open so at the same time I reached over a slaped the handle closing the valve.
    Not much hit the ground thank heavens. My sister thought it was quite humorous after the fact. At the time though she slipped into the background thinking there might be a bit of irritation in the area.

    I guess that I neglected to close the wastegate after the last tank dump.

    We traded the trailer in on a motorhome since then but I use a clear section of pipe now with a wastegate on the bottom so that won’t be happening again. 😉

  • Tom Draggoo

    We bought our 1974 El Dorado fifth wheel from a friend of a friend who was an auto dealer so we got precious little information. Imagine my surprise the first time I pulled the black water tank T-handle and blew the hose off the connector because no one had thought to mention the necessity of a hose clamp. Yes, it was messy, not to mention hard to explain to the RV resort owner. That was 40 years ago and I still remember how frantically I was trying to push the handle back in.

  • Nice post/video! We haven’t had the “opportunity” to explore this area yet since we are still renovating our RV, but I’m glad you suggested the better quality hoses. Ours has one of those reddish colored ones…I figured they were all the same but I guess not. You may have saved my life!…or at least saved me from cleaning up a mess 🙂

  • Suzy

    I think the more people we tell out not using your drinking water hose for any other purpose is really important. We have been in line at the dump station and watched in horror as people fill their fresh water tank with the hose that just was inserted into someone elses sewer hose.. It is hard to watch. I would like to know more about ways to keep the fresh water and grey water tanks free of sludge and build up. They say you should never pour bleach down the drains to sanitize. So What do we do? I can image sludge building up over time even with the best of cleanliness. What do you guys do to maintain your fresh water? Do you ever flush it our or use anything to keep it fresh?

    • Suzy

      When you say “sanitizing spray” any type you would put the Winn seal of approval on?

      • We actually use a mixture of 2 parts water to 1 part vinegar… because vinegar is natures best cleaning, deodorizing and disinfecting solution!

  • Dominick Trentacosti

    It’s never a bad idea to spray the CG water connection with disinfecting spray since the last person who was using it probably had his black water hose on there last thing before he left.

    Thanks for another great video!

  • A dumping horror story – with lessons learned!
    We’ve been full time RVing for about 6 years now… Toward the beginning of our Full-timing.. we experienced an especially cold winter in Lexington, KY… We (being new) thought it’d be a good idea to leave the inside water drip overnight.. but.. if we have the grey tank closed, this will fill up and overflow.. The obvious decision was to let the grey valve remain open too…

    The next day, we realized our black tank needed dumping.. I walk outside, close the grey tank and wing open the black valve. There was the immediate and expected woosh… then it just stopped. A quick check found that the stinky slinky had clogged with frozen grey water from our overnight drip.

    So, as the hose is relatively compressible.. I thought, hey, it can’t be that frozen.. so I can just compress the hose a bit w/ my foot to knock the freeze loose. Turns out, the hose is *not* that flexible when that cold… (8 Degrees F if I remember correctly).. The hose ruptured under the pressure of the waste and my foot compressions…

    Poo’cicles everywhere!

    A quick trip to the local home-improvement warehouse to pick up some lime powder… and that spring yielded exceptionally green grass!

    Lessons Learned:
    * Don’t drip your faucet overnight.. Instead, bring on water to your onboard tank, and disconnect/drain your freshwater hose.
    * Consider picking up a heated hose, or making one if you’ll be in cold weather for any period of time..
    * Don’t leave grey (or black) valves open full time in extended below freezing temperatures..
    * Don’t kick a clogged hose in very cold temperatures… they become VERY brittle!

    Happy trails!
    aka Linuxkidd

  • Randy

    Sprinters don’t all have that issue, my grey tank is under the trunk, and black is behind the driver’s rear tire. The back corner is where both outlet into a single hose fitting. Many LTV Serenitys have a macerator attached, I had one fitted aftermarket.

    The sink in the bath runs into the black tank so lots of water mixed into the black. Still have faulty tank readings that will not clear with ice or calgon splashing around the black tank before dumping. Custom switch panel means I cannot upgrade to externally mounted sensors…

    Dumping was faster w/o a hose, but the contents of my tank dumped onto the skirt of the dump site and needed to be washed away. Stinky, gross. Now I don’t see the contents, really became white glove, despite the extra wait for all the contents of the tank to be pumped.


  • Robert L

    I didn’t see anything black coming out of the black tank….are you guys aliens?

  • Many RVs don’t have the black tank flush connections. On our Navion iQ, the only way to get water into the tank is through the toilet.

    To complicate matters, there isn’t a common outlet that the hose connects to. There is a hose connection for the grey tank and a hose connection for the black tank.

    That makes the process a little more interesting. (Dump the black and flush from inside. Close the gate valve. Move the hose to the grey connection and dump the grey.)

  • Ami

    I love the “enzyme every four dumps” for the gray tank…and the tip to open it lightly to check for leaks – would’ve never thought of the latter (until I’ve had some type of horrific tank dump accident), and the former will save some money! Love your site, excited to check out the new features! I’m so envious of you guys and your life on the road, but am thrilled with the fact that our family gets to go out and RV as many weekends as we can…especially once school is out. Next trip is just a couple of weeks away!


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