There is a real concern about what the future holds for RV dump stations. RV dump stations everywhere are closing down operation because of several reasons. Some, but not all of these reasons are the costs and headaches involved to keep them operating and properly maintained, the wrong types of chemical treatments used by RVers, and because of neglect and poor housekeeping by RVers who use these dump stations.

RV holding tanks are used to hold, or store waste water until a sewer system is available to empty the tanks. Because little water is used, in comparison to a domestic wastewater system, RV holding tank wastewater is far more concentrated. Adding to the problem are the chemicals required to assist in breaking down the waste and controlling odors. This requires more treatment than a regular house type waste system and it complicates the disposal of RV holding tank waste. In many cases it is much easier to just close the dump station.

The problem that the average RVer is confronted with is how to control holding tank odors. Formaldehyde based chemicals do a better job of controlling odors. The problem with this is the organic strength from the mixture in an RV holding tank can be fifteen to twenty times stronger than a typical wastewater system. This leads to more complications for dump station owners. This problem is compounded when the RVer gets some odors from the holding tank and dumps even more chemicals in the holding tank in an attempt to control the odors. Environmentally friendly enzyme based chemicals use natural organic chemicals. They have a lower organic strength, which is better for the dump station but they don’t control odors as well as formaldehyde compounds. Note: There are inexpensive aftermarket products, like the RV-360, that effectively work to control holding tank odors. View the RV-360 installation video

Something else to consider is how much water you add to the holding tank when you use the toilet. Think about the toilet in your house. Even water saver toilets use about 1.6 gallons of water when you flush it, plus there is water in the bowl. The water level in your holding tank can help to control odors. You need to get in the habit of adding additional water to the holding tank whenever you flush the toilet. It is absolutely necessary that you keep the water level above the contents of the holding tank to assist in controlling odors and to prevent future holding tank problems.

Another thing that I think happens frequently is that people don’t add enough water after they empty their holding tanks. You need to know what size holding tank you have and make sure you add enough water to completely cover the bottom of the tank each time you empty it. One RV holding tank might only need three or four gallons to cover the bottom of the tank where another one might need six or more gallons.

It’s important that we do our part to make sure RV dump stations stay open and operational for the future of RVers everywhere. Here are five easy steps we can take to do our part.

1) Use plenty of water in the black water holding tank.
2) Use enzyme based holding tank chemical rather than formaldehyde based chemicals.
3) Use only the amount of holding tank chemicals recommended for the size holding tank you have.
4) Practice good house keeping every time you use a dump station. Imagine that you are the person that has to clean up behind everybody else.
5) Never dump your holding tanks anywhere except in authorized dump stations and campground sewer systems.

Happy Camping,

Mark Polk

RV Education 101

RV University

Leave a Reply


  1. I camp for long periods and have never used any chemicals. There are plenty of bacteria that are designed to do that job of breaking of down the paper and … effectively. If you have been using chemicals then it takes time for the bacteria to build up. When living in my RV with 2 on board I dumped 2 x a week at most and often could manage a 1x week trip., and this is with showers too. It is amazing how little water you can manage with if you plan and are careful.
    I also use much less water as I use Happy Bowl toilet bowl liners , they save using water to clean the bowl as it doesn’t need cleaning after using Happy Bowl liners. It also saves the unpleasant job of cleaning the bowl; you can find out more and get a free sample pack on my website. They were given product of the month in the Camping World flyer.

  2. Maxine Mougeot

    One way I add extra water to the black tank is to empty the hot soapy dish water into the toilet. I have a nice little dish pan which I wash dishes in so it is easy. The hot soapy water works wonders – I have not used much black tank treatment and never had an odor problem.
    Maybe cleaning it out really well is the answer but the extra hot soapy water can’t hurt.

  3. Sue – Try going to the homepage of your manufactuer. Often there or perhaps on the specs page there will be a listing for the specs of past years. Look around the site carefully and do a search if it is available there. For my model, I was able to find the holding tank capacities back to 2002.

  4. IMO there is no reason to use chemicals in your waste tanks. I bought and installed the wind venturi’s on the vent pipes about 3 years ago and haven’t used chemicals since nor do we have odors coming from the tanks except when we dump. When we use the RV every weekend we only dump every other weekend. We haven’t been using our motorhome the last few weeks except we stay in it at our house once in a while. The black tank is close to half full and we haven’t dumped in probably two months. Still no odor.

  5. These are some good comments. I’ll try to answer a few of your questions.

    Sue, there is no easy way to determine the capacity of your black water holding tank. One method would be to take a 5 gallon bucket and when the holding tank is empty continue adding buckets of water through the toilet until the tank registers full at the monitor panel, or until you can see it is nearly full using a flash light to look down in the tank. If you’re lucky it will be a reasonably small tank!

    Ian, Years ago dumping gray water on the ground was more acceptable than it is today. Whether dumping the gray water on the ground is acceptable or not depends on several factors. One being the state or possibly the federal lands where you are doing it. Some states and federal guidelines prohibit dumping gray water on the ground. In some cases bathroom sink and shower water might be okay, but kitchen sink water can contain solids which is considered the same as blackwater.

    Vetrncwby, You would need to check with local officials to make sure you can empty the holding tanks into the city sewer line. I have talked to RVers who got permission to do this and others who cannot. Not being allowed to do this would probably be due to the authorities not knowing what was used to treat the contents of the holding tanks. I personally have a septic tank and empty my holding tanks into it if I wasn’t able to empty them prior to returning from a trip, but I only use enzyme based treatments which are fine with septic tanks.

    Barbara, I don’t recommend using bleach in holding tanks. Too much bleach will damage holding tank valves, seals and gaskets in a short period of time. And even though bleach kills the bacteria that is causing odors in the holding tank it can also kill the bacteria in the wastewater treatment facility contributing to failure of the treatment system.

  6. Barbara Chedester

    Are you saying, no bleach? AZ doesn’t allow bleach but most do.

  7. TXBrad

    Good reminders & info for RVers.
    However, Federal, state,local, & comercial parks are all in this issue w/ us.
    Some parks have info on dumping w/ Park Rules Handouts; suggest more operators incl. info ( help renters newbees) and some need to better repairmaintain the site connections plugs.
    If, we all do not work together, our wacked out Washington officials will pass a law ! Already after Pig Farmers : pigs expell Gas & affects Global warming !!!!

    Tx Brad

  8. rcsly

    In over 20 yrs of RVing I have never used chemicals in my black water. I flushed the tanks with a hose through the toilet to keep it residue clean. I have always had a flow through top on my vent pipe and flush that pipe a couple of times a year [I now have the vent top with the wing that controls it even better and a direct flush from the outside on my Pina]. Purchase, (1) a pail to catch any drip while attaching and detaching (2) a proper dump hose and always (3) check the clamps before using said hose.
    I wrap my hose into a square plastic container with a top to collect anything I may have missed. It is easier and less embarrassing to clean that other than the pavement. I never smell our toilet and have a good sniffer.

  9. My wife and I just returned from RV camping in Argentina, where they really don’t even have any dump stations. As you can imagine, this restricts what type of RV one can use (ie. no black water tanks) and dramatically affects the overall experience. So, thanks for posting this article. It’s a good reminder that we RV’ers in the USA need to appreciate our blessings and properly maintain these services.

  10. Roxie

    I, too, have wondered about dumping into the city sewer outlet that is behind my house.

    I have been very mindful of using only biodegradable products that contain no formaldahyde. I have recently been adding more water after emptying the holding tank. So far I have not had any odor problems!!!!

  11. judie rose

    We have been rving for many years. We use Rid-X for our black tank. After we dump we empty the ice maker into the commode and flush. This serves double purpose of dislodging anything dried and stuck and puts water in the tank as well. We have never had any trouble with odor or not being able to dump.

  12. You can’t dump grey water in most parks. I sometimes do when it’s full, but only dump enough to make it until you dump. I saw a newbie dump his black water and someone had him dump his grey in the park with nothing left to flush out his hose! yucky

  13. Vetrncwby

    Is it legal to dump your RV holding tank into the city sewer line that comes out of my house?

  14. Ian McKee

    Good advice on black water tank care. I needed reminding about keeping a minimum level of water in the tank.
    Another issue rarely discussed is gray tank disposal. I lived in Santa Fe, NM for about five years just before I bought an RV. The southwest has been in a multiyear drought and a recommended practice there is to recycle your gray water from your house to the garden, gray water being shower, kitchen sink, laundry, etc. Yet I meet many RVers who consider dumping gray water on the ground a sin. Obviously, you don’t do it in a paved lot but a grassy one?

  15. Vegasdan

    I hope that everyone takes this to heart and not ruin this valuable service for everyone. I sometimes wonder if many of the problems regarding this could be the folks who rent an RV for a week or two and have no training on what to do or how to do this properly.

  16. Sue

    How can I find out the capacity of my holding tank? I bought my RV second hand and don’t have the manuals.

  17. Eric Strom

    Thank you for this timely post! We’ve been RVing for less than a year, and have only been out in a situation where we had to use the holding tank 2 or 3 times.

    Every one of these RV.NET posts reminds us of what a lousy job our dealer did “briefing” us on the use of our RV.

    For instance, we never knew we needed to keep water in the black water tank, other than the amount initially put in when we add the chemicals. But this makes total sense.