Dave Solberg

How to Sanitize Your RV Waste Holding Tank

Dave Solberg
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Over time the RV waste holding tank can begin to smell. This is caused by a build-up of bacteria and other waste products left in the tank after dumping. Even if you properly dump your RV waste holding tanks and use the appropriate cleaning chemicals in the tanks, it is still important to take the time to thoroughly clean and sanitize the grey and black water tanks. It is a good idea to do this every now and then, especially before putting the RV in storage.

The best way to clean and sanitize your RV waste holding tanks is to fill the tank with a bleach and water solution. To make the solution, mix one-quarter cup of bleach with one gallon of water. The total amount of bleach-water solution you will need depends upon the size of RV waste holding tanks you have. For most, eight gallons of this cleaning solution should be enough.

Completely fill the tank with the solution and leave in the RV waste holding tank for at least eight hours. It will be best if you are able to fill the holding tank with the solution before going on a long drive. This way the fluids can swish around inside the tank, breaking up any residue left behind. Doing this will clean up and sanitize any pathogens left inside your RV waste holding tank. The bleach-water solution used to clean the tank is safe to dispose of at a dump station. Completely drain the holding tanks into an approved dump site.

If you plan to put your RV in storage or do not plan to go out on the road for a long period of time, take some time to clean and sanitize the holding tanks. This will kill all of the bacteria and ensure you have a cleaner, nicer smelling holding tank when taking your RV back out on the road.

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21 Responses to “How to Sanitize Your RV Waste Holding Tank”

    • Customer Service

      Hello Terry!

      We’d love to help! Could you give us a little more information about the issue you’re having with the tank?

      Thank you!

      Jessica
      RV Repair Club Video Membership

      Reply
  3. Michael J Pomante

    You CANNOT SANITIZE AN RV HOLDING TANK…BLACK, GRAY, OR OTHERWISE!!! Duh!!! Retired Mortician/Undertaker/Embalmer

    Reply
    • Customer Service

      Hello Ramona,

      Bleach at full strength left in a pipe with rubber seals for a long time may begin to break the rubber down, however if diluted properly as indicated on the side of the bleach container and left overnight will not affect any of the components in a plumbing system.

      Typically I use about 1 cup bleach for every 50 gallons.

      Thanks,
      David RVRC Video Membership

      We’d love to have you be a part of our community. We are convinced you will enjoy the benefits of becoming a member and having access to the best instructional how to videos and professional tips. We would like to offer you a special promotion for your first year membership.
      https://go.rvrepairclub.com/C11174

      Reply
    • Carl R Shepard

      I rent my RV out and stopped using bleach because it did make my valves tough to close…I realized I was ruining my seals. However, I was using a far stronger concentration. I use a tank cleaner, then flush with a sanitizer like bleach or Mr. Clean, but not so strong now. I always rinse it out though…I never let it sit for days. In order to keep the seals “soft” I put fabric softener in there after the rinse and I will let that sit for days.

      Reply
  5. Mike

    I work in the water/waste water business and I am very familiar with the dangers of bleach. There for I don’t use it. I use a box of baking soda and vinegar. This will do just as well and make everything smell fresh and not “bleachy”. Hope this helps.

    Reply
  6. Terrence

    I was told by an RV shop that bleach can damage pump seals. Also, what is the best way to “refresh” a holding tank that has odor? I’ve heard that adding baking soda is a good method.

    Reply
    • Customer Service

      Hi Terrence. If you look at the label on the side of a bleach bottle, you will see the recommendation for mixing a small amount of bleach with water, usually 1/4 cup to 1 gallon. This mixture will not deteriorate the rubber seals or gaskets used in RV water systems if just used to flush the system out
      and not letting it sit for weeks on end. I’ve used bleach for 33 years in RVs and had no problems often times using it to remove stale
      water odor from fresh water tanks. My wife does not like the smell of bleach so I use the flowery scented version and it has always gotten
      rid of the smell and taste and left a pleasant scent. Baking soda is also good to get rid of the odor, but not as effective. Thetford
      also makes a product that you can put in fresh water tanks for odor treatment.

      Reply
  7. Tom

    Thank you for the useful information. However I would like o point out something about your comment on bleach and arsenic in a well. Arsenic is a heavy metal, and bleach has no affect on it in any way. Bleach will shock a well and help eliminate bacteria, just not arsenic.

    Reply
    • Customer Service

      Hi Tom. Thanks for visiting the RV Repair Club and clairifying the arsenic comment. You are correct, adding bleach to a well will provide a “Shock Clorination” and is meant for high levels of bacteria and not arsenic. There are specific treatments/filters for arsenic which fortunately is not a common problem with RV water supplies.

      Reply
    • Customer Service

      Hi Tom. Thanks for the update and correct information. I was even told by a plumber a few years ago that he shocked my grandparents well for bacteria and arsenic? After your comment I researched and you are correct, arsenic can only be treated by anion exchange, reverse osmosis, activated alumina, and other types of adsorptive media filters depending on the type and severity.
      Thanks again, it’s a good day when I learn something new!

      Reply
  8. Chris

    The video said usually 8 gallons will be enough to sanitize your holding tanlk but it also said to fill the tank. My tank is 40 gallons. I don’t understand why it said 8 gallons is enough and then they said to fill the tank?

    Reply
    • Customer Service Techs

      Hi Chris. Thanks for visiting the RV Repair Club site and watching the sanitizing video. The 8 gallons stated in the video was referring to using a 1/4 cup bleach with one gallon of water and making 8 gallons of this and then fill the tank with regular water. You are right, it is a little confusing, so with a 40 gallon tank, I’d recommend dumping 2 cups of bleach into the tank and filling it with regular water.
      Thanks for the catch!

      Reply
  9. Val

    I read a story a few years ago about someone putting bleach in their holding tank not knowing there was a bit of waste left in it. I’m not a chemist but I guess urine will turn into ammonia after a few days of sitting. When this person put bleach down their toilet it mixed with the “ammonia” and caused a very foul smelling bomb that blew out the exhaust vent and rained down on their RV. I have never put any bleach products in my toilet since reading this!

    Reply
  10. Steve Korsvall

    My profession is hydrocleaning holding. I have special jetters that scour out the tanks.

    Reply
  11. Terry Moore

    My travel trailer manual specifically states not to put Bleach in any of the holding tanks as it will cause damage.

    Reply
    • TERRENCE

      Customer Service – please comment on whether using bleach in holding tanks can be an issue.

      Reply
      • Customer Service

        Hello Terrence,

        I have used bleach for years in a holding tank without any issues other than my wife does not like the smell of bleach but hates the smell of the holding tank even worse! I typically use only about an 1/8th of a cup per gallon so a 40 gallon tank would take 10 cups or about one small bottle of bleach and 30+ gallons of water. Drive around for 15-20 minutes and then let it sit overnight. It will be fine to dump into an authorized dump station as that will be connected to a treatment plant system.

        Thanks,
        David RVRC Video Membership

        Reply
  12. Jeff

    Good article on cleaning the tank. I have used this method for years. It is also advised to use a little Liquid Laundry Soap as well. Many laundry soaps have a disinfectant quality as well. I will use this method when I start out on a trip and then completely flush the system at my first RV stop. Never have had any odors in the coach!

    Reply

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