Tips for Efficient Flushing of an RV Holding Tank

Man servicing an RVThe last thing you want to do while taking a road trip is to have to pull over in order to dump and clean the holding tank. Do not overthink this process and let it get in the way of you enjoying your time on the road. Though it is not a fun job, it is not a very difficult one either. As long as it is done properly and routinely, you should have no issues with your RV holding tank during your travels.

Here are some tips to help you efficiently flush your RV holding tank:

Gather all of the supplies you will need before flushing your tank at an approved RV waste site or connect up to one at the campsite. Supplies needed include a hose dedicated to dumping gray and black water tanks, flush hose, hand sanitizer, disinfectant wipes, and a good pair of heavy disposable rubber gloves. Some seasoned RVer’s use an inhale filter, however done properly, you won’t have to much odor when dumping.

Your first step is to check the dump valves (the large one is for black water and the smaller one is for gray water) to make sure they have both been closed. An open valve means there will be waste water at the cap and you’ll have quite a mess when opening it. With your gloves on, remove the sewer cap and attach the clear adapter to the drain valve. This product allows you to see when clean water is flushing through the tanks. Add the dump hose to the adapter and ensure there is a tight seal before continuing.

Cleaning drains

Carefully carry the hose to the sewer connection or the dump site’s drain system and attach the hose. Most dump hoses have special engineered fittings to make a secure connection. If not, you will need some type of weight on the hose to keep it down in the dump station hole.

Pull the valve on the black water valve to empty the black water tank first. If you have a black water tank flush, attach a garden hose and run water at the same time to help flush out the solids. If you do not have a black water tank flush valve, run water through the toilet by depressing the lever at the toilet. This will take 2 people as one will need to watch the flow. You can also run a hose through the bathroom window and connect a toilet wand.

Once the flow seems to be clear, it’s a good idea to close the valve and fill the tank up with water to about ½ full. Open the valve again and you will be amazed at how dirty the water is after it seemed to be clean! If you have more than one black water tank to dump, always dump the back or furthest away from the valve.

After the second flush of the black water tank, close the valve and open the gray water tank valve. This is much cleaner shower and sink water and will make it easier to clean the dump hose when you are done. Once done, disconnect the hose from the sewer dump and the RV. Carefully coil up and place in its storage area. Securely close the drain cap and make sure all valves are closed.

Run additional clean water in both tanks and add an approved tank solution to the mix. This will help clean the probes, lubricate the valve, keep odors down, and disinfect. Only dump the tanks when they get more than ½ full to help get rid of solids in the tank.

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57 Responses to “Tips for Efficient Flushing of an RV Holding Tank”

  1. Deb

    Our sensor readings are always incorrect. Is there a way to clean the sensors so that the black water reads properly

  2. Steven Larson

    What do you do when you run across a campground dump station flushing hose that does not have a garden hose fitting. You will find this at National parks and National campgrounds. Sometimes they have a wand with a compression fitting or just a hose with no fitting at all. I lose more water than I use trying to hold this up to my RV inlet that wants a garden hose type connection.

  3. Steven Larson

    My black tank only partially drains (maybe 40%) unless I flush it. Then, after quite a bit of water builds up, more of the solids and toilet paper come out in a rush. After a while the clear water appears. Is this normal. I would think that quite a bit more should come out prior to flushing. The way it is it makes it difficult when there is no sewer hook-up at the site. I only get a partial dump into a Rhino waste tank leaving most of the solids in the RV black tanl..

  4. Michael Hammett

    Looking for a complete owners manual

  5. Deanna Long

    how di i identify and update the water inlet hoses the fresh water inlet broke and a man rigged it so it would only run with city water on he used pvc pipe and i paid him befor seeing what he did im a disabled cancer survior and buy the grace of GOD Imarried a man a year ago knowing how sick i am he is not a mechanic my any means but with the direction and advice he could fix whats wrong im 57 and hes 62 id like to go rving when he retires problem is we live in illinois and we are in south texas wherei bought the rv before i met him i am a disabled nurse hes a wonderful husband with no rv experiece neither do i but the rvtrips and life has been a dream of my for decades i know your all busy and enjoying your rv life but any advice would be a gratful blessing bless you all and thank the lord for this website again any help or advice would be an answer to my prayers abd believe me I pray all the time i want to be an rver more than anything with the time i have left with my wonder husband. He can do construction, electrical, plumbing,dry wall and mudding, cabinets and flooring and carpet laying hes great at it all but that homes and apartments and rentals but when it comes to RVs hes almost completely

  6. Martha Barthle

    What do you do if the black tank valve is stuck closed?

  7. Dale Lucas

    I want to flush out my gray water tank. I will put in a solution then add fresh water. the container I am using says add 50% fresh water. Which would be 35gals. Is there another way to add water to the tank other than the shower and sink.

  8. Ronita Adams

    I tried to use the "sanitizing the lines" levers and also "sanitizing the black tank" levers.When I turned the water on it ran for a couple of minutes and then water started coming out of the overflow lines (like it does when you fill up the fresh water tank). It has never done this before. I also didn't hear the sprayer arms in the black tank like I usually do when I put it on tank sanitizer. I am wondering if there is a clog in the lines somewhere. The black and gray tank both empty easily so the clog isn't there. How can I fix this please?

  9. Tamela Hassell

    Toilet won't drain and nothing is coming from the black tank and the valve is open?

  10. Kathleen Gensman

    How do I empty the 2nd grey tank? Preparing for a freeze