Get Some Control Over Holding Tank Odors

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June 21, 2009

Holding tank odors can be a real problem, especially if you don’t know how to deal with them. If you are new to the RV scene, this issue is perhaps the most popular complaint (aside from dead batteries!). When purchasing a new RV, part of the delivery process is explaining how to empty and rinse your holding tanks, as well as preventing holding tank odors by using chemicals. But on a particularly hot day, even chemicals can’t stop the odoriferous emanations gagging you out of your RV. It’s the same problem porta-potties have which everyone has probably experienced at one time or another. So what can you do to assist in controlling tank odors? Do the Lil’ Stanker holding tank fan mod.

The Lil’ Stanker fan mod consists of a 12-volt powered fan and a switch to control fan operation. The fan mounts over the top of the black water holding tank vent pipe on your RV’s roof. When switched on, it provides suction, helping draw odors up and out of your holding tank. The fan also has a shroud that prevents water from entering the fan assembly and is similar in shape to the standard vent pipe cap.

The company that makes the Lil’ Stanker roof fan also has another option to fit a fan inline with the tank vent pipe. This type of fan is located inside the RV rather than on the roof. If you have easy access to your holding tank vent pipe inside the RV, you may opt for this type of arrangement. It’s both easier to install and wire up than the roof mount type since the fan is simply a slip fit. It is contained within a housing whose ends fit standard-sized RV vent pipes. And you don’t have to feed the wiring down the vent pipe as is the case with the roof mounted fan.

Both types of fans have two speeds: low and high. The low speed is recommended in all but the most stinkiest of situations. The fan switch is a three-way switch with off being in the middle. So it’s easy to tell what speed the fan is on at a glance. There is also a power indicator to show when the fan is operating, but doesn’t show whether it’s low or high speed.

There is also another type of vent pipe mod you can do to help draw odors out of your holding tanks. It’s a replacement vent pipe cap that has an angled fin (for lack of a better term) which follows the direction of the wind. It provides a venturi effect which creates a vaccum at the end of the pipe. This draws out smelly air from the tank. The only drawback to this type of odor controller is that it requires air movement to work. Going down the road, it works great. But if there is little to no wind when your stationary, it won’t work as intended.

Doing this mod, in conjunction with regular draining, rinsing, and sanitizing of your tanks with your favorite odor-eating concoction, will have you getting some control over those pesky tank odors. And don’t forget. You can also do this mod for your gray water tank as well!

For more information, installation pictures, and wiring diagrams, head on over to and have a look at this article:

Happy modding!

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  1. Pingback: YUCK! Get rid of your holding tank odors | I Love RVing

  2. I use HAPPY CAMPER and it workes very well, no strong chemical smell , even when you are dumping there is very little or any smell .

  3. Pete Woodward

    Please the amount of Calgon and Bleach for the mixture….. Thanks Pete

  4. Richard

    Like many others, that most awfull odor would meet me each time i stopped and entered the trailer. I gave it much thought and finally realized that it was the turbulence in the air passing over and past the roof vent that caused a positive pressure on the vent pipe. As a diagnostic atempt, i removed the vent cap. To my relief that odor was no longer present when we stopped. Yes i may get a few drops of rain water down the pipe when it rains however a four inch rain would give me less than a 1/4 inch of water in the holding tank. My stinky problem has been solved for free. I now have a slightly used vent cap looking for a new home.

    Richard W

  5. EDC

    Regarding controlling odor in holding tanks. We spend January thru March in Florida. During that hot mostly dry time we have experienced odors from our “Black water tank”. We do use the toss in chemical packs, lots of water, and empty tanks about every 3 days. And, generally leave the door open to the bathroom “Commode area” to allow for better general air circulation through the camper.
    I agree with the comments about the water being sucked out of sink and shower traps causing some problems. One thing we do when on the road is always place the “Stoppers” in all sinks and shower drains before traveling. This will help to keep water in the traps while on the road.
    We are going to install one of the 360 degree Vents on our “Black water Vent” yet this fall.
    Also, the posting that “Dan & Jill” made on June 21st about only using “Bleach & Calgon” in their black water tank. I would like to try that also. I would like to know if they are using a specific mix of the two, or just dumping in a little of each one every 3rd dump. Appreciate any info they might share with us.


  6. Thomas Becher

    check somehow to see if the vent is properly put into the tank. mine was just shoved in the hole they drilled for it and never sealed. I put some of that sticky caulk that they use to seal the campers where the sides meet the caps (under the aluminum edge) and that took care of my stinky problem. Also, when you flush some smell can come up from the tank. Do it quickly. Dominic Sealand has a new residential type toilet coming soon that has a trap to hold water and so smells out. No blades or seals and balls. Expensive yes.

  7. M Guay

    If you take everyones thoughts and combine them, this is the simple fix. After you dump, re-fill all the traps, sinks, shower and toilet. As you dump your systems through a 3in hose you draw more air than a 2in vent can handle, thus sucking the water from the traps. If you install this fan….how much air is going to be extracted from your tanks? It isn’t strong enough to suck the traps dry. Therefore there is no intake air….hense if there is no source of intake air, there is no exhaust air. A waste of electricity, if dry camping. On the other end of the spectrum. If this fan is installed, it will further restrict the vent intake durring the dumping process……sucking the traps DRY!

  8. W Tourtillott

    Most tank stink problems happen on the road when traveling with a side window open or a roof vent “cracked a little”. The reason is that the air traveling along the sides (and top) of the rig forms a venturi. It’s strong enough to make the traps gurgle and flood the room with that familiar “perfume”.

    Try traveling with the windows and vents closed. Use the “flow through” setting on your driver’s controls to keep a little positive pressure in the coach. Chances are you’ll solve the problem right there!

    If you don’t have these stinky issues while you’re sitting still at a campground, It’s an odds – on bet that this is your answer. If that doesn’t do it try those “weathervane” swivel tops for at least one of your grey water vent pipes. They’ve done the trick for every one I know who’s tried them.

    Good luck!

  9. Jake Heugel

    The reason oders ocurr is that the vent pipes are usually 2′ diameter while the dump outlet is at least 3″. As the pulls in air, it needs an opening more than 2″. The vacuum created draws water from the traps in the grey water. The problem can be elimianted by placing a thin rubber pad over the shower drain and closing the sink vent. The tank may drain slower, but will eliminate inside oders after a dump. This is also true where a sing on a 2 bathroom system empties into theBW tank. Plugging the sink is a must in this case. I use Pine – o – Pine after the last wash and keep it and a few gallons of water to slosh and clean going down the road.

  10. Pingback: RV Weekly Round-Up (June 20-26, 2009)

  11. Rich D.

    In my opinion, “Lil Stanker” is not a solution to the problem, just a way to cover up a problem caused by a malfunction in the vent system. If you are getting odors into your RV, as others have said, it is probably from a dry trap. The tanks should be sealed from the RV interior by water in the traps or by water in the toilet bowl. If they are full and you still get an odor check for a broken or slipped vent pipe.

  12. I think Taz has the answer. Keep the traps full. I don’t understand how sucking air out the vent will help if the traps are full. Could even empty the traps.

  13. Taz Ciesla

    The shower is the lowest fixture in almost all rigs.

    When you drain the gray water holding tank, it may suck the water out of the shower p trap, thus allowing odor from the gray water holding tank to vent into the rig. Gray water can stink pretty badly.

    Just add about 12 ounces of water to the shower drain and see if that doesn’t eliminate the odor.

  14. I placed two very small 12V “muffin fans” in my black water tank vent and capped it with an inverted stainless steel bowl. Total cost: about $8.00. I ran the wire down the vent to a switch (SP-DT-center off). With the switch in the low (series fan wiring, yellow LED on) the current draw is a measly .05A. With the switch in the high (parallel, red LED) position, the draw is still only .25A.
    Presto! No more odors. The wiring exits the vent tube (sealed) in the corner cabnet, the switch resides on the cabnet side. Current easily (well, maybe not REAL easily) accessed from the bath light switch. Another cheapo fix.

  15. Jim the Tucson Traveler

    I don’t have any odor after using Happy Camper for about 3 years.

  16. Dave Planitzer

    The roof vent sounds like an ideal application for solar power.

  17. Hi All.

    Myself, I think the Lil’ Stanker Holding Tank Fan Mod would be a waste of money and time. Lets start with the roof mounted version:. “Ah”, where do you plan on getting your 12 volt power from ? Are you going to drill a hole throught your RV’s roof to get the power there ? Are you going to try and tap into your Bathrooms Celing Light, and try and fish feed the 12 volt power to the vent pipe, and then up along side the vent pipe to the top of your RV’s roof ? Now the Bottom Version: Getting power to the underside of your RV isn’t a big deal. But are you acutually going to break the seal on your RV’s roof vent, in order to lift the vent pipe up and out of the Black Tank to hook up the Lil; Stanker Holding Tank fan ?
    Myself, I have found the 360 Degree Black Tank Vent to work very well. And the way its worded, it made to sound like it needs a lot of air movement to even work. Actually it takes very liitle breeze for it to work. We have used our 360 Degree Black Tank, and Gray Tank Vent ever since they first came out. We don’t have any problems with oders, even on very hot days. A good part of keeping oders down in the first place, is to keep your Gray and Black Tanks
    as clean as possible. Next, in very hot weather, dump your Tanks often. We don’t use any cover up smelly chemicals. The only thing we ever add to our Gray and Black Tanks, is some Bleach and Calgon, about every third dump. Keeps things slick, so things don’t stick to the inside of our tanks. That, and a lot of water. Just one RV’er’s thoughts. Good Luck. Happy Camping. Dan & Jill

  18. soricobob

    In the Southwest, where dry air takes on whole other meaning, I find that a lot of odor(s) can be eliminated by running water. That is, after not being used for a while, before heading out of storage, I run the water so all the traps are full. You see, the water evaporates so fast out here that the traps empty and the odor escapes after about 3-5 weeks in storage.