Skip to Content

RV Holding Tank Dumping 1-2-3

RV Holding Tank Dumping 1-2-3

Dumping your RV’s black and gray tanks might seem like a no-brainer, but we can’t tell you how many times we’ve seen people who could use a little help with the basics. Properly dumping your RV’s holding tanks requires a few simple procedures to help keep things odor-free and running smoothly.

For everyday tank dumping, this video is the “express version” of our original “How To Dump & Clean an RV Black Tank.” If your black tank really needs a super cleaning, you can watch the original, more detailed video here:

How To Dump & Clean an RV Black Tank

If you’re not having tank odor problems and just want a quick overview of basic tank dumping procedures, this new video gets right to the point.

Many RVers seem to think their black tank is clean when they just empty it and flush out the sewer hose with water from the gray tank. Even those RVers who use a black tank flush system often don’t utilize the most important piece of equipment necessary for monitoring the cleanliness of the tank: a clear sewer elbow.

But using a clear sewer elbow on your camper isn’t enough. As we demonstrate, even a black tank flush connection still won’t do the job unless used correctly. We’ll show you how to be sure your black tank is really empty, keeping it clean & odor-free and making your motorhome, travel trailer or fifth wheel a nicer place to be.

Recent & Related Videos:

Featured & Related Products:

We'd Love It If You Shared This!

This site uses Akismet to reduce spam. Learn how your comment data is processed.


Sunday 29th of August 2021

We just figured out the issue my husband is having with tiny flies in our RV are most likely sewer flies.

We use Happy Campers Organic.

Is there some other product to use for sewer flies?


Sunday 29th of August 2021

Hi Diane. Sorry to hear you’re having a problem with bugs! We’ve never had an issue with “sewer flies”, but suspect that what they really are may be “drain flies.” The lower water flow down RV sink drains (especially when dry camping) can result in organic matter building up in the drain pipes themselves. And that dark, wet, nutrient rich environment is a perfect breeding ground for “drain flies” which, since you see them flying up out of the sink drains, etc, makes it easy to assume they’re coming from your black/grey tank.

Try treating the affected drains (or ALL of them if you’re not sure) with Happy Campers (mix it up and pour it slowly down each drain so it coats the pipe walls). That will eat away the organic sludge on the pipes and remove the home the flies have made. If that doesn’t work, you could also try using a foaming drain cleaner for the same effect.

Last, but not least, check out these tips from This Old House:

Good luck… we know how annoying bugs can be… even when they don’t bite/sting. 🦟🐝

Phylis Forsyth

Thursday 20th of June 2019

I have a private lot with water, electric, and a septic tank. I replaced the black tank hose and thought I had all the fittings to the camper closed and tight. When I started emptying, got an unwelcome surprise and quickly shut it off. Is there an extra part that I’m missing?


Wednesday 3rd of July 2019

Hi Phylis... without seeing your setup, it's a little hard to tell. If it was leaking from one of the fittings, it sounds like you may have a bad clamp that's not sealing properly. Sorry we can't be of more help... but we sure hope you get it fixed up!


Saturday 7th of July 2018

Hello! I'm about to try Happy Campers Extreme on my black tank. (Kind of excited actually). Does anyone know how long it can sit in there without harming the tank? We will be gone for a little over 24 hours this weekend and thought this would be the perfect time to treat the tank, but I don't want to harm it... ~ Katie


Saturday 7th of July 2018

Hi Katie! There’s no reason that you can’t keep happy campers extreme in the tank as long as you want to, and actually the longer it’s in there, the better it will work. That said, of course, follow the manufacturers instructions


Monday 15th of January 2018

I have a 2017 Montana fifth wheel that the black tank empties very very slow. I am considering checking the vent pipe to ensure it is not clogged but having three vent pipes on my roof, I'm not sure which is the black tank vent. Any suggestions would be greatly appreciated.


Monday 15th of January 2018

Hi Ron,

Sorry to hear you're having trouble! There's a couple of ways you should be able to go about identifying which vent pipe is for the black tank... some more desirable than others! ;)

You can do the "nose" test... and just get up on the roof and take a whiff from each one. While the gray tank won't smell like roses, either, you should easily be able to tell the difference between them. You can do the "ear" test... have a helper open the toilet and pour water into the black tank, slowly (it helps if there's already some water in the tank) while you listen at the vent pipes on the roof. When you hear the sound of water pouring in, you've found your pipe. We've heard of people removing their vent caps and using a hose to put water into the tank from the roof. By checking to see which tank begins to fill up using their monitor panel, they know which tank that vent is for. On the plus side, this technique can also help to clear anything in the pipe that may be causing the lack of air flow... but if there IS a blockage, this could also end up having water pour out somewhere it shouldn't. We wouldn't want to rely on the vent pipes being water tight... since they weren't designed to be.

There's a couple of things to consider:

Depending upon the layout of your tanks, one tank could have more than one vent pipe to the roof. As an example, our black tank is "U" shaped... and is installed so that the upper legs of the "U" extends up around the chassis rails. As a result, there are two vents for it, one on each side coming out of the top of each leg of the "U". This ensures that if the tank fills up to the point that there's isn't a path for air across the top of the tank between the upward facing leg sections, each side still vents. It's possible (and not unheard of) that what's causing your problem is a piece of the tank wall itself. When they make the tank, they cut the holes in it for all of the plumbing connections... and, sometimes, those pieces are left inside the tank. When that happens, they can end up finding their way to the drain pipe and clog it. We hope that's not your problem, as it's quite difficult to get that removed... and it's quite a messy/smelly job since the tank doesn't drain properly with that in the way. You may want to try doing a soak with a heavy-duty waste digestor (like Happy Campers Extreme or NoFlex Waste Digestor) to see if the blockage is organic. Fill the tank with fresh water and a healthy dose of either of those two products and let it soak for a couple of days, then see how it drains. If nothing else, it should help to clear out any organic matter/tissue that's clumped up around a possible disk of plastic from the tank wall, allowing it to drain better so it won't be so messy getting out that piece.

Hope all of this helps... and let us know how you make out!

Nancy Carter

Wednesday 31st of May 2017

I am set up with a plumbed sewer line to a septic that others on the property are also using. My issue is while I opened the blank tank (after opening the grey tank and hearing the water empty) the black tank also sounded like it emptied into the same sewer line (septic). The light indicator shows the blank tank is still at about 75 % full. My question is how to I empty the black tank? I can't see what else I can do? I must be doing something wrong otherwise it would empty on it's own wouldn't it?


Wednesday 31st of May 2017

Hi Nancy! There are a couple of possibilities here. The first thing to determine is if the indicator is showing 3/4 full due to a sensor malfunction rather than it actually being that full. Even though you're connected to a permanent sewer line, gravity should be doing the job of draining the black tank. It sounds as though you're not making the (serious) mistake of just leaving the black valve open, so pyramiding (liquids running out and leaving solids behind in a pile) shouldn't be the issue. You should be able to tell if the tank is really 3/4 full by seeing if you have very little capacity after dumping. If only a day or two goes by and your tank shows full, it was indeed likely 3/4 full, as indicated. If you can use the tank showing 3/4 full for a considerable time without it going to a full indication, it's likely just a sensor issue (showing 3/4 when it's really not). That would best be dealt with by doing a good tank cleaning with a product like Happy Campers Extreme Clean:

This site uses Akismet to reduce spam. Learn how your comment data is processed.

PLEASE NOTE: We're handy RVers, not professional technicians. We're happy with the techniques and products we use, but be sure to confirm that all methods and materials you use are compatible with your equipment and abilities. Regardless of what we recommend, consult a professional if you're unsure about working on your RV. Any task you perform or product you purchase based on any information we provide is strictly at your own risk.

We participate in the Amazon affiliate program, which provides a means for us to earn a small commission by linking to products there. But our opinions are our own and we only link to products we can recommend to friends with complete confidence. And using our links won't cost you an extra penny!

$750 My Magic Carpet Giveaway - 2 Winners!

Enter Now!
00 days
00 hr
00 min
00 sec