Odor Control in your RV – Part 1 – Venting

February 21, 2008 by Gary Bunzer · 25 Comments  
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Holding tank odors are a definite problem experienced by the vast majority of RVers. But there is good news; relief is available! By following correct waste management practices, checking for proper venting and by using a few aftermarket products I recommend you can all but eliminate and certainly minimize those dreadful odors that seemingly plague us all.

First, fully realize that odors can originate in either the black water or the gray water holding tank. Foul odor is not limited to the toilet tank only!

That said, let’s take a look at a few areas within the RV waste system.

One important aspect of proper RV waste management is understanding the dynamics of holding tank venting. Each holding tank must be vented from the holding tank up and through the roof to the outside atmosphere; the typical vent consist of 1-1/2″ ABS plastic piping. Here’s an issue — Oftentimes coach manufacturers cut a very large hole in the roof for this vent pipe to pass through; it makes the installation a little easier. Sometimes this vent opening may not be sealed properly all the way around the pipe. In other cases the vent pipe itself may not extend far enough above the roof line. According to the NFPA 1192 Standards on Recreational Vehicles, “each vent pipe shall pass through the roof and terminate vertically, undiminished in size, not less than 2-inches above the roof.

But if you have a short vent pipe (less than 2-inches above the roof), and the area around the pipe is not sealed and an oversized hole exists, then it is entirely possible for tank odors to pass up the vent pipe, hit the roof of the sewer vent cap and bounce back down beside the pipe into the ceiling area where it makes its way to the living area and you inhale the results. Not all tank odors are lighter than air!

So, from the roof, pop of the top of each sewer vent on the rig and be sure the area around the vent pipe is sealed properly (no gaps anywhere around the full circumference of the pipe) and that the pipe itself stands at least two inches above the roof. Extend it by using an ABS coupling and a short piece of pipe if necessary.

In some cases, depending on the method used to connect the vent to the top of the holding tank, vent pipes have fallen down inside the tank, nullinfying any venting action whatsoever and allowing tank odors to exhaust well before the roof line, virtually within the ceiling void or even inside an interior wall pocket trapping odors inside the living sections of the RV. By inspecting the vent regularly, this can be avoided.

I actually recommend replacing stock sewer vents with one of my favorite aftermarket add-on products; the Xtreme Vent produced by Coil n’Wrap.

Xtreme VentThis unique roof vent operates around the Venturi Effect which, in simple terms, stats that as air is passed through the vent, it decreases the static atmospheric pressure inside the holding tank and literally draws vapors and subsequent odors out of the tank through the vent pipe.

The vent rotates 360-degrees and is made of heavy duty metal as opposed to plastic. This vent is indeed durable. The pivoting action is very smooth and it captures even the slightest wind. A 1-MPH breeze entering the vent opening creates 4-MPH air movement inside the vent pipe. Just imagine the effectiveness of ram air while driving down the road! The air moving through the vent actually sucks odors and vapors out of each holding tank. The faster the incoming air, the quicker vapors are drawn out of the holding tank. Installation is very simple; any handyman can replace an existing sewer vent with an Xtreme Vent.

Another added benefit, although I have not yet personally substantiated it, is that the lowered static pressure creates an oxygen rich environment inside the holding tank, thereby maximizing hte efforts of the natural (or added) enzymes breaking down the solids and tissues faster and purportedly more completely.

That’s it on venting; in my next few posts I’ll talk about additives, waste system components, holding tank blockages, and corrective evacuation procedures and how they can assist with controlling odors in your RV.

Gary Bunzer, The RV Doctor

View Part 2 – Additives

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25 Responses to “Odor Control in your RV – Part 1 – Venting”

  1. mike and pat maw on February 22nd, 2008 4:30 pm

    Good writeup on this subject. We had an oder problem and it did smell like the holding tanks and we used all the tricks that you can think of to get rid of the smell and nothing worked. The smell was comming from the washer because the water would stay in the lines and after awhile would start to smell the same as the holding tanks. To solve the problem we ran a rinse cycle and it cleared it up. so some food for thought.

  2. DAN on February 22nd, 2008 5:17 pm

    i have found that if you flush the toilet with a ceiling vent fan running, it sucks air down the roof vent pipe, through the blackwater tank and into the coach. very smelly. if you close the ceiling vent and turn off the fan before flushing, this doesn’t happen.

  3. butch on February 23rd, 2008 7:29 am

    I have been using an extreme vent for about two years now and my wife’s sensitive nose has not detected an odor since it was installed. PS we do not use any tank deodorant.

  4. Karl on February 23rd, 2008 8:17 am

    On 3 separate occasions we noticed a sewer smell coming form the vicinity of our holding tanks and could not immediately find the problem. Finally after doing some investigation and downloading the drainage piping drawings from the manufacturer, we found there was a P-trap located on the discharge for the Washer/Dryer. When we had the local Honey Wagon come and suck out our tanks we found that they were pulling the water out of this trap and leaving it dry. The odor was coming from an area near the washer dryer and entering the coach through a sliding door opening.

  5. Stan & Ginny on February 23rd, 2008 9:41 am

    Our solution to oder from the holding tanks has been amazingly simple – not my idea, got it from another blog – it works great!!

    On a regular basis we put a cap full of Calgon Water Softener (we prefer the liquid form but dissolved powder works as well) into the tanks after being drained. We keep the tank drain closed to allow the Calgon to work (releasing any material from the walls of the tank). We also put a small amount of clothes detergent (bio-degradable) in the tanks as well. We do this almost every time we empty the tanks but it really is not necessary to do it every time. We have not used any of the chemicals sold for tank cleaning purposes. They did not work!

  6. TOM on February 23rd, 2008 2:12 pm

    Where is the Extreme Vent sold? Are two indicated for grey & black vent pipes?

  7. Pat Mackes on February 24th, 2008 5:32 pm

    We’ve talked to people who have the Xtreme Vent, who give it rave reviews. These people are full-timers. Our question is this: We are not full-timers. We camp about every other weekend from April through October and wonder if the Xtreme Vent is the answer for us. Before we make the investment (we have 2 black water tanks and 2 gray water tanks), we’d like some feedback from those who may have an insight. Thanks.

  8. Bob J on February 28th, 2008 8:30 am

    Tom: Here is the website for the Xtreme Vent…

  9. Sooter on February 28th, 2008 2:47 pm

    Funny how all the solutions to most RV related problems evolve buying some miracle gadget .
    We had stinky tanks bought something very similar to this product . Well it did not help with the smells !
    What finally made our tank smells vanish was treating with Cheap and readily available house hold bleach .

  10. Bert T. on March 3rd, 2008 10:11 pm

    I agree with Stan & Ginnys comments. I’ve recently just started 2 days ago following the directions given on a web site I found called, a site run by Dale & Gwen (last name unknown). I found the web site by reading the above article about the Extreme Vent and subsequently an article by Dale at, where he supplies an article on the “GEO- METHOD” used in an article titled “Black and Gray Water Holding Tank Maintenance Using Water Softener, Laundry Detergent, and Chlorine Bleach. In a nutshell, dissolve two (2) cups of the water softener in a gallon of hot water. Then, pour the solution down the drain into the empty tank. Use two cups of softener for each wastewater tank in your RV. (I did it with my black tank 2/3 full & it immediately got rid of the odor I had). (As stated by Stan & Ginny, use Calgon Water Softener as this water softener seems to work better according to the author of the “GEO METHOD”). The tank’s drain valve should be closed otherwise the softened water will just drain out. Then use the tank(s) normally until it is full and drain it normally. Add a cup of laundry detergent to the black (commode) water tank at the same time you add water softener. This will help clean the tank. The gray water tanks should already contain soap through normal use. The article states that Gwen quit using RV Tank chemicals and uses regular toilet paper. He subsequently switched to the Extreme Vent eliminating the use of the “GEO METHOD”.

  11. Odor Control in your RV - Part 4 - Tank Blockages on March 13th, 2008 8:00 am

    [...] activate your subscription. Thanks for visiting and enjoy all the information! RV.Net Blog AdminIn part 1, part 2, and part 3 of this series of posts I’ve discussed how venting, additives, and waste [...]

  12. Gary on March 13th, 2008 2:59 pm

    Thanks to all who have left comments regarding my holding tank odor submissions! I apologize for not posting sooner; I’ve been on the road for 3-1/2 weeks and just got back to the office.

    I’d like to follow-up with a few of the above comments if I may:

    Mike & Pat: thanks for your comment. Indeed it sounds like stale water had accumulated. Another item to check for the washer/dryer, the P trap. In some cases of infrequent use, it’s possible the water level in the P trap has become depleted enough to allow odors from that tank to enter the coach. See Karl’s comment above. It happens!

    Dan: I’ve seen your situation when the holding tank vent pipe exits the roof very close to the bath vent. You’ve found the solution to an otherwise impossible remedy without have to reroute the vent pipe.

    Butch & Pat: Indeed the literature from Coil ‘n Wrap suggests that chemicals or additive are not even needed when using the Xtreme Vent. Obviously a great fix for odor control.

    Bob answered Tom’s question, thanks Bob!

    Sooter: Man where’s your sense of adventure? Just kidding of course. Whatever works for you is your best solution. I am a fan, however, of natural methods of holding tank maintenance by using live bacteria and unfortunately, bleach kills bacteria, so it’s either bleach OR bacteria. Too strong a bleach concentrate, however, can have a damaging effect on the rubber seals in the holding tank valves. Just like many roads can lead to a destination, so many fixes can be applied to RV maintenance issues. Appreciate your input!

    Stan & Ginny & Bert: Same thing again…bleach and detergents may indeed work fine, but may have long-term consequences for other components. Personally I’ve not tried the geo-method, but Bert’s shared good results. Is this a great country or what?

    Thanks to all who’ve taken the time to post. I’ll be getting to the other comments as time allows. Cheers!

  13. Bert T. on March 17th, 2008 6:00 pm

    I’d like to add an addendum to my article above. I do not use any bleach in my holding tanks due to the water softener & detergent getting the job done. I also might add that I still use 2 to 4 oz of tank deodorant as an added measure. The softener and detergent work great at keeping waste solids from sticking to the bottom of my holding tank as suggested in the GEO METHOD article. Where it was sticking before, it now no longer does. My toilet drain is right above my tank inlet, and by shining a flashlight in the hole I can see if the bottom is clean. I also have a black water tank flush which also helps. For those who have a problem with waste solids not evacuating on the first drain from the bottom of your black water tank, a simple solution exist that I read in my Good Sam Highways Mag. Using a 5 gal pail/bucket of water, pour it as quickly as possible down the toilet, after emptying the tank to the sewer. This produces a fast and voluminous flow of water into the tank. This works best if the toilet entry to the black water tank is opposite the drain exit from the tank, thus allowing the flush water to travel across the floor of the tank to the exit drain, taking the solids with it. I was doing this until I started using the water softener and laundry detergent. The last drain I did, I had no solids stuck to the bottom that I could see. For real stubborn solids, the article suggests two to three such flushings.

  14. Tami on March 20th, 2008 9:35 am

    We have Keystone Raptor 5th wheel and last year while camping we noticed a terrible smell coming from the grey water holding tank which the shower and bathroom sink drain in to. Tried everything we could do to eliminate the odor. It appears the vent cover popped off. Would a extreme vent take care of this problem? We tried tank cleaners and they didn’t work. Please help us out with some suggestions. We are only able to camp on weekends and look forward to enjoying our camper, but the smell is soooo bad. Thanks.

  15. Odor Control in Your RV - Part 5 - Evacuation on March 20th, 2008 10:38 am

    [...] activate your subscription. Thanks for visiting and enjoy all the information! RV.Net Blog AdminIn part 1, part 2, part 3 and part 4 of this series of posts I’ve discussed how venting, additives, [...]

  16. Mark Hamilton on April 16th, 2008 7:24 pm

    I’m a full timer since 2003 and spend alot of time in the hot Arizona Desert in the summer when holding tank odors can be most offensive. I purchased the xtreme vents by coilnwrap after comparing them with the cheap plastic alternatives found in the RV stores and Walmarts. I decided on the Xtreme Vents because they are vastly superior in craftsmanship (power coated aluminum and well crafted internal parts) to anything else I found. They work GREAT! No odors anytime, anywhere PERIOD! While I agree that there are alot of gadgets out there that are probably not necessary, I give the Xtreme Vents two thumbs up and highly recommend them as a REAL solution to RV odors.

  17. keith on May 22nd, 2008 5:34 pm

    How do you know which is the black water vent & which is the grey water vent. One of mine is located above the shower and the other above the bathroom sink. The one above the shower would be closest to the toilet.

  18. David on June 22nd, 2008 12:21 pm

    After reading the posts, my response was either a light went off in my head, or it was one of those Duuuuuhhh moments. I have been going crazy running down the sewer odor, most notably when the bath fan was on. Then I read the postings here about the washing machine water trap. We have not used the washer in well over a year, following the advice here, we ran a cycle and guess what, the odor went away. I had examined every drain, every possibility and never considered the washer sitting in a cabinet in the same area. One last thought, another discovery. I have a 99 Beaver Marquis, in my search of the phantom odor I discovered Beaver, using some questionable at best logic, did not vent the bathroom sink to the outside. Instead they put a stub on it, right under the sink, just out of sight unless you use a flashlight and stick your head under there. This stub is vented, vented to the space under the sink. Now, wasnt that brilliant? And someone some where fixed the problem by covering the vent holes with good old fix everything duct tape. If you have a Beaver coach you might want to look under your bathroom sink.

    Thanks for this page, you made my day……

  19. Joe on February 26th, 2009 1:01 am

    Has anyone herd about this brand new product called RV Shocker?

    It easily remove any severe odor including pet, cigarette smoke, mold and mildew odors by completely sanitize the interior within two hours. It is revolutionary new technology that makes Chlorine Dioxide and its benefits available to the general public. Chlorine Dioxide is the strongest and yet safe biocide which up until now has only been accessible to large industries like food packing plants and sanitation, to eliminate odors disinfect and decontaminate.

    The company introducing the product is Biocide Systems. They are so confident in the results that they offer a money back guarantee.

    The product works very much like a fumigation bomb. It comes with a cup you add a little water and let sit for four hours in the RV.

    Not only dose it remove the odor after two hours but it literally sanitized the entire interior leaving it smelling crisp and clean.

    a great benefit to any RV enthusiast.

    This was my experience.

    My family and I took the RV out over this past Presidents’ Day weekend. We went to one of my favorite spots near Kennedy Meadows. As we were packing up the final things to head home our dog decided to dance with a skunk. As you can imagine our dog lots and darted right into the RV. By the time we were able to get Rosco our dog out of the RV and wash him down the skunk odor had permeated the entire RV and everything in it. We were left with no choice but to suffer a four hour road trip with the awful smell. Needless to say the ride home was one of the most challenging experiences but that’s another story in itself.

    When we finally got home we had a professional auto detailing company come out on an emergency call. They steamed cleaned the carpets and cushions then they sprayed an enzyme cleaner. It did not put a dent in the odor. The next day they tried using an Ozone machine. $400 later no major improvement.

    Then my daughter-in-law insisted I go to a website called She used a product called Room Shocker to get rid of cigarette odors out of a vacant apartment she needed to rent out. She claimed it delivered the most amazing results and bet me it would work or she would pay for it. When I went to their website I was pleasantly surprised to find that they not only had a Room Shocker for homes but also an RV shocker and Boat Shocker. I went ahead and ordered the RV Shocker for $24.95. It was at my door in the next morning.

    I follow the instructions and set off the RV Shocker. After two hours I peeked my head in the RV to check on everything and I could smell a chlorinated sent but no skunk odor. I could not believe my nose. I went ahead and stepped in to the RV and was baffled when I realized the skunk odor was gone. I was literally in an overwhelming state of disbelief and shock. I immediately took the cup out and put it in the storage shed where I placed all the items that were tainted in the RV. I’ve opened all the doors and windows to the RV to air it out. Within 20 minutes the chlorinated smell was gone and no skunk odor left. I then brought my wife in for the final approval. She literally had tears of joy when she relies that the odor was gone and our RV was back to normal and even better than before.
    Not only did it remove the skunk odor but it also removed the stubborn pet odor and left the RV smelling crisp and clean.
    A couple hours later everything in the shed was the same crisp and clean. Even the damp mildew odor in the shed was gone.
    Amazing is the only word to properly describe the results.

  20. Merl and Gisele on June 14th, 2010 11:31 am

    We have been full-timers since 1998 and have been able to deal with any odors that have occurred in both the black and gray water tanks in our 5th wheel. During the off season, we use a truck camper and this spring when we de-winterized it, we noticed a “skunk” smell in the bathroom. We have checked the venting system, have used all the methods we know of but to no avail. The smell seems to be coming from the sink drain – we would appreciate any suggestions.

  21. JJ Henry on October 13th, 2011 1:36 pm

    If you are like me and did not do all the research about RV odors before owning one, then you let all the odors come in the RV, then did all the repairs and steps necessary to fix the problems, but you are still stuck with a smelly RV because the odors were absorbed into all the furnishings. My friend told be about RV Shocker, an odor eliminator. I was skeptical, but it actually worked. All the smells are gone. It is also environmentally friendly, so there are no harsh chemicals. I highly recommend it to anyone. You can find it at

  22. JJ Henry on December 15th, 2011 5:45 pm

    I have had a lot of success with RV Shocker. It works like a fumigation bomb but for odors. Therefore, the product gets deep into the upholstery killing the odor at its source. It doesn’t have any harsh chemicals and it’s easy to use. Check it out at

  23. Jim Yeager on January 28th, 2012 5:31 pm

    We have a 2007 Cedar Creek 5 th wheel we use infrequent mostly during the summers we use it all summer on weekends, we did not use this last summer of 2010 we recently used the r v and it reeks of a moldy smell and the smell is brutal it sticks to cloths and anything and everything in the unit. I took two stress less chairs out a number of months ago and put them in our home and they smelled like mold for months. I have metered the entire unit for leaks and there is no visible signs of damage to do with leaks. My wife brought a bag of cookies back from the unit last week after we stayed in the unit over the weekend and even the plastic smelled like mold. The sheets we cleaned in our home washer smell of mold after being washed twice, what the heck could be causing this stink? Our unit is cleaned serviced and maintained by professional services? I have read on your site about the washer p drain etc.. We have a washer and dryer in the coach, is that the culprit?

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