Gray and Black water tank cleaning.

February 6, 2008 by William Gotthelf · 27 Comments  
Print This Print This ·

If you're new here, you may want to subscribe to our E-mail Digest or RSS Feed. We will then send you the stories that are posted each day in an e-mail digest. We use a service called Feedburner for delivery of these emails. You will receive an e-mail from Feedburner after you subscribe and you must click on that email to activate your subscription. Thanks for visiting and enjoy all the information!

RV.Net Blog Admin

You mean I have to clean them? Well yes you actually do. Gray water tanks accumulate soap scum on the sides of the tanks because most of the time people leave the valve open when camping so the tank mearly has water pass through it. Old soap scum along with food particles eventually will combine to make some nasty odors. If you have been camping for any length of time you will hear many different ways to freshen the gray water tank and in turn improve the accuracy of your holding tank gauge.

 Before your next camping trip go to a pool supply store and buy a 32 ounce bottle of de-foamer solution. This is used in spa’s to eliminate the foam caused by detergent residue in peoples swimming suits. Stop and pick up 2 lbs of baking soda. Now after your next camping trip and before you head home fill the gray water tank about a third of the way. Add 6 ounces of the de-foaming agent down the kitchen sink and let the faucet run for a few minutes. Okay now drive home. The sloshing of the tank will neutralize soap scum and wash the tank walls clean. Leave this solution in the tank until you head out for your next camping trip or next campground. Before you head out add the 2 lbs of baking soda through the kitchen sink running water again for a few minutes. When you get to the campground dump the tank and you have cleaned out the gray water tank.  Black water tanks are cleaned a little differently but moving the camper sloshing the mix around helps it get cleaned out also. So you could do both on the same trip. First, one of the biggest mistakes campers make is keeping the black water valve open when camping.


This is a no no as that allows the liquid to leave the tank and solids to build up. I have seen tanks so plugged we had to use a pressure washer to open them up. In the good old days all there was was a very strong smelling blue liquid that had formaldehyde in it. It did a very good job on odors but was very hard on campground septic systems. Today you have dozens of choices and the most environmentally correct are the enzymatic additives available from any camping supply store. These do a great job breaking down solids and actually help septic systems but don’t do as good a job of controlling odors like a formaldehyde based tank additive. You should wait till the tank is at least 1/2 full before dumping to allow these chemicals to act and liquefy wastes. If you have been camping and keeping the black tank valve open you can still clean the tank. Either way starting with an empty tank fill balck water tank about 1/3 of the way and add the recommended amount of black water tank additive. Some people have said adding a bag of ice will help but I find the tank gets clean enough from the constant sloshing of the water/additive mix. Drive home or to the next campground and at the next available hookup dump the tank. This should be enough to clean the tank and restore accuracy to the black water tank gauge.  Now for the black water tank smells that will be next week…..

[Slashdot] [Digg] [Reddit] [] [Facebook] [Technorati] [Google] [StumbleUpon]

Most Commented Posts

Last 5 posts by William Gotthelf


27 Responses to “Gray and Black water tank cleaning.”

  1. 2oldman on February 7th, 2008 7:59 am

    A couple or three paragraphs would make your post easier to read.

  2. DocHoliday on February 7th, 2008 9:13 am

    Never use a drain cleaner in either tank. 8-10# of crushed Ice + non-sudsing ammonia + 5 gallons water, through the commode just prior to traveling will take care of most buildup problems.
    Or, the tablets used in your dishwasher will slosh around, break down, and take the grease and soap scum off.
    Safe travels.

  3. wigglesnwoofers on February 7th, 2008 3:32 pm

    A cup of Calgon and a cup of Tide(use regular tide, not the bleach or downey type) mixed with warm water and throw most down the black and the rest down the grey, add about 4 gal water after down the black(toilet) and this keeps our tanks sensors working, I do this when I return from a trip and leave it until the next time I dump after a camping trip. I also add a chemical packet when I leave for a trip. No problems with sensors for several years and now on our fourth camper.
    hope this helps

  4. Justiceb on February 7th, 2008 4:30 pm

    I think your complete explaination was perfect. Reason and results are what most new rv’ers don’t know about. I picked up some new ideas to try from your article. Keep up the good job and I look forward to your next post!

  5. William Gotthelf on February 7th, 2008 7:49 pm

    2oldman thanks for the info. I am new at this blog writing and the format we write in is different than any word processor program I have used. Hey one day I’ll get the hang of it. :)

  6. FullTimerNormie on February 7th, 2008 9:03 pm

    What is the best way to clean tanks if you are parked for a few months straight and not moving, and using the tanks everyday?

  7. William Gotthelf on February 12th, 2008 8:11 pm

    FullTimerNormie make sure you let the black water tank fill before you dump it and use a good enzymatic additive to help break down solids. These generally do a good job of keeping the tank fairly clean. You can also buy a wand that attaches to a hose and is placed into the tank thru the toilet connection. This uses water pressure to help keep the walls clean in the tank. There are also attchments that you can buy that attach to the dump connection and have a builtin hose connection. These again use water pressure to back flush the black water tank. Some campers come with a tank sprayer built in to make flushing even easier.
    As far as the gray water tank let it fill up and use the same defoamer I talked about above. Use that for a tank full and the next tank full add a box of baking soda. Let each stand for a few hours before dumping.

  8. Getup'ngo on February 15th, 2008 3:19 pm

    My MH has a black tank flushing system. Due to an unbeknownst-to-me problem with a black tank valve that won’t completely close, I developed a lot of sludge. I’m trying to clear out more of the buildup each time I dump the tank. When I attach a hose & turn the water on, the tank flushing system sounds like it uses a rotating spray. Is that what it’s doing? I’d like to know more about the internal tank mechanics. Anyone?

  9. MooseLodgeRV1 on February 16th, 2008 6:46 pm

    Black water valve closing problems can be minimized by leaving the valve open a short time after the black water tank has emptied and fill the toilet with clean water and flush. Doing this once or twice each time you “dump” BEFORE closing the black water valve will help assure all solids are flushed by the valve — allowing it to totally close – and help avoid it sticking.

  10. beverly on February 17th, 2008 5:05 pm

    we are thinking on buying a winabago 27ft cambera…any complaints anyone have

  11. William Gotthelf on February 23rd, 2008 7:21 pm

    Getup’ngo usually builtin tank flushing systems usually do rotate in the tank. They are usually mounted high on the tank so as to be subjected to the least amount of buildup. Camping supply houses sell a wand that has a rotating head with fine jets of water that spray out to help clean out tanks also. You hook up a hose to the end and put it down into the tank through the toilet. They do a very good job.

  12. Linda C on May 5th, 2008 8:08 am

    Help please. Our black water tank is not emptying. Unfortunately we were not told to make sure the tank was 2/3 before empyting. What do we do now? The valve to empty it opens and closes fine. Might we fill it to 2/3 and then drive it around and try again or do have to start taking things apart?

  13. Bill Gotthelf on May 19th, 2008 6:32 pm

    Linda if you fill tank about 1/2 to 2/3 of the way full, add about a 1/2 cup of detergent and drive around. Iit should loosen up the buildup you have from keeping the valve open. You may have to do this more than once. After it starts flowing again fill the tank completely with water adding 4 ounces of one of the “green” black water tank additives. If you let sit for awhile (days) and then drain you should be back to normal.

  14. TommyT on June 6th, 2008 3:33 pm

    Linda, you may have to get one of the clear plastic elbow fittings that connects to the sewer outlet (between the outlet and the hose) and includes a fitting to attach a garden hose to in order to backflush the system. They have a fitting that prevents any backflushing into the gray hose. If there’s much build up at the black water valve, you might need the reverse pressure to “shake” everything loose. I’ve only had to do it once, but it sure made life easier, and cleaner.
    Are you sure that the valve’s shaft hasn’t disconnected from the valve plate? I just replaced the valve on mine because the shaft pulled loose from the valve plate (door). I got it open by removing the “T” handle from the shaft, reversing the shaft (so that the threads went into the valve housing first), and , using pressure and pliers, managed to screw the shaft into the plastic plate. Then, I was able to get the valve open so that I could drain and flush the tank and replace the valve assembly. But, I’d recommend trying everything else before removing the valve!! The entire process was very unpleasant.

  15. Tom Bender on July 29th, 2008 12:31 pm

    I always install a tank rinser in my black water tank. About $30 and an hour labor if you can read and follow directions. Need drill and drill bits, and a screwdriver.
    Good luck

  16. stephen on August 2nd, 2009 4:05 pm

    I bought a 40 sierra cbra 2 years ago it sits in a aprk. I have no mannual how do I nd clese levers for black and grey water no one told me how to do correctly??? Help

  17. Dan LIlis on December 7th, 2009 6:17 pm

    My wife and recently moved into our 5th wheel trailer so pay debt. So, my problem is the solid waste in the black water tank is building up. I have had to have a septic tank company come and pump out the tank. How can I keep the solids from building up in the tank?
    Thank you very much

  18. Don Zimmermann on February 18th, 2010 11:08 pm

    All the suggestions certainly will help, but in inspecting thousands of holding tanks with a fiber optic camera I have discovered that the major problem of odors and build up is mineral deposits from the water and urine. Cleansers will not remove it. The only proven way all foreign matter can be removed is by high pressure hydrojetting. I question the wisdom of the enzyme treatments also. The do break the solids down, but they turn into a paste that is heavier than water and ends up drying out in the bottom of the tank. How does that help? My camera reveals that once a tank starts to clog, pumping and roto rooter only break a pathway through the sludge and it just clogs again. Hydrojetting will correct sensors and throughly clean the tanks.

  19. Breeze on June 3rd, 2010 10:40 pm

    We just got our 06 Fleetwood prowler regal 5th wheel. We are living in it for now and are new to the R.V. life. Our problem is gnats. I think they are coming from the toilet when flushed. They are annoying . Has anyone had this problem before and how do we deal with it ? We would welcome any tips too. Thank you from El Paso, Tx.

  20. YUCKIE on July 9th, 2010 7:12 pm

    We always have used the drop ins with our pop up…well when we upgraded to a travel trailer we continued the same process. We use public facilities for all BM. We have screen catches in the bath and sinks. Every now and then the black water would just trickle out. The sensors kept telling us it was 2/3 or full and at that point the water should gust out. We did the ice and that helped a bit, but the problem continued. Finally I said forget it, I am using the liquid we have for the gray water tank to see if that helps. Almost immediatley the sensors went from reading 2/3 to 1/3. On departure however, when we opened black water valve…notta. We took out the water hose shoved it up as far as it could go, turned on the water, and opened the valve. The hose went in, we then knew it wasn’t the valve. Well out started coming the toilet paper (which is only one ply camping paper) and with it the drop in packs. Its like they got stuck and clogged everything up. I will NEVER use drop ins again.

  21. bbwolf on August 15th, 2010 3:41 pm

    We found an interesting product for eliminating the black water gases and smell. It turns out that the MaxxAir covers we installed allow us to keep the vent in the roof open, even when we drive. That, and anytime we partially open a window and drive, was the reason we were ending up sucking the black water tank gases into the RV through the toilet venting inside the bathroom. Something to do with low pressure caused by the air we were bringing into the coach?

    Well anyway, after researching for a solution we found one that did not require any moving parts and would cause a constant “draw” pulling the black water gases out of the vent on the roof, like it should!

  22. bbwolf on August 15th, 2010 3:45 pm

    We just took a trip after putting the new vent cap on, and even with the fantastic fan running, or just open while driving (and covered by the MaxxAir cover), we had NO MORE sewer gases coming inside the coach. We had windows open, vents open, driving down the freeway and it actually worked.

    The product is a 360 vent. (I am just an RVer, so I have no affiliation with these folks, but I really am sold on it).

    Watch the video demonstration in the center of the page: (inside the white strip of words)

  23. C. Howell on December 11th, 2011 1:36 pm

    Since staying in an RV that we have rented, we are experiencing dizziness and headaches. Checked for carbon dioxide and clear on that. Also sensor is not registering any propane leaks. Could it be the black water tank? We are not experiencing any foul odors from the tank.

  24. bud on May 18th, 2012 8:03 am

    does any black water tanks have a flap about 6 inches below the toilet slide . I baught a aljo 5th whell and it looks full and the top is very hard almost like plastic

  25. Rockford Devilliers on June 12th, 2012 2:44 pm

    Johns Creek Septic Tanks Hey I had been just wandering around the web and identified your website, certainly glad I did because it had some from the details I had been in search of for any report for school, thanks.

  26. Homepage on July 6th, 2012 12:57 pm

    … [Trackback] …

    [...] Informations on that Topic: [...] …

  27. get pregnant fast on July 29th, 2012 1:00 pm

    get pregnant fast…

    I saw this really great post today….