Friday, October 7, 2022


Hold down summertime holding tank stink

“I stink, therefore I am,” says my philosopher. He lives under my RV, and travels everywhere with me. He’s a rather nondescript fellow, about six feet tall, four feet wide, and a thin six inches thick. He seems to prefer a dark suit. In fact, every time I lay eyes on him, he’s laying about, clad in the black skin of plastic suited to folks of his kind. Although he is never invited inside, from time to time he does—in an awful way—make his presence known. He is a windy fellow, and many of my associates simply state, “He’s full of it.” And so he is, for my friend the dark philosopher is a black water holding tank.

Hot weather fanfare

We’ve found these fellows usually make the most fanfare during hot weather. They can’t really help it, it’s just their nature. So what can we do to make summertime RVing as “nose-comfortable” as possible? Here are a few tips:

Odor from black water comes from the naturally stinky nature of what we put down the pot. Some holding tank treatments deal with that by masking the odor with perfumes or other deodorants. Others deal with the smell by reasoning this way: Since the breakdown of the waste is what’s causing the smell, stop the breakdown and you’ll stop the smell. These “biocides” do just that: They kill all bacterial action in the holding tank, the wastes stop breaking down, and the odor, to some degree stops. How well these work in really killing the odor is rather subjective, and can certainly be affected by outdoor temperatures. The hotter it is, the worse the stink.

Treatment-free an option?

Some RVers tell us they don’t use any sort of holding tank treatment at all. Almost universally among these we find that most thoroughly flush their black water holding tank every time they dump it, and few venture into hot climates. If you do choose to skip the treatments altogether, the consensus of RVers is to “get it out of there as quickly as you can, preferably in a week or less.”

That’s a tough assignment for some. Since it’s not wise to dump a holding tank if it’s less than three-quarters full, a rig with a large holding tank could go a LONG time between dumps. Our fifth-wheel’s 40-gallon tank only required dumping every three weeks when we full-timed. On the other hand, since we were boondocking most of the time, we were pretty careful about how much water we used to flush. So, if you want to move-it-in, move-it-out quickly, don’t spare the flush water. Flush away to your heart’s content and fill up that tank with water for a quicker release.

Au naturel?

When it does come to treatments, we lean toward the more “natural” bacterial-enzyme treatments. We found them to be quite effective in keeping the odor down, and in keeping the tank free of buildup. Ah, but when summer’s warmth came, we did find some issues.

One foul-smelling experience occurred when the combination of heat and non-motion did “shut down” the bacterial action in our tank. That was bad! To get out of that problem we had to empty the tank and fill it completely with water and a large dose of baking soda. After 24 hours we emptied the tank, then started using it again with a fresh dose of our favorite “natural” treatment. The odor was gone, and we were happily back in business.

The stuff we’ve been using for the last couple of years, is “Happy Campers.” It’s a powder that’s scooped into a full toilet bowl of water after the tank is dumped. Flush down into the empty tank and let it do the job.

holding tank

What’s in it? Here’s the manufacturer’s statement: “Happy Camper is a highly concentrated monohydrate blend of minerals and micro nutrients.” Eh? “There are nine trace elements and two heavy elements that make up a highly concentrated blend of minerals and micronutrients. In layman terms, it is the good bacteria doing away with bad bacteria to eliminate odor and accelerate the natural decomposition of the waste. It has the ability to work longer and stay odor free in over 100° temperatures.”

Apparently California doesn’t think the stuff is “natural” enough, because you can’t buy it in or ship it to the Golden State. Anywhere else, you can buy the stuff from Amazon. We’ve been happy, and with 4.7 stars out of 5 rating, we aren’t the only ones.

Dump more often—and keep movin’!

Our experiences lead to warm weather holding tank tips. As we’ve already pointed out, the more often you dump, the happier you’ll be. Here’s the corollary: Keep moving! The more you stir up the contents of your holding tank (logically, by driving) the fewer odor problems you can anticipate. Besides, the more you keep moving, the more of the country you’ll see!

What about treating your gray water tank? Few RVers ever do much of anything about treating their gray tank. We recommend you abstain from pouring grease down the drain, but for the most part, a gray tank will give you few problems.

Wrinkle up your nose—here’s more on the subject:



Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Inline Feedbacks
View all comments
Rey L.
4 months ago

Interesting…I live in Ca. & have ordered & received “Happy Campers”.

4 months ago

The Bio-Geo Method Works For Us : )

4 months ago

so for us unfortunate Californians that used to use Happy Campers, what do you recommend?

Jeffrey L Kirk
4 months ago

I have found over the years the majority of “black tank odors” are not from the black tank. They are odors from the grey tank. This happens when the water in the j traps dry out and let odor into the RV. The shower that is not used except for storage is notorious for this. If you smell a “black tank odor” run water in sinks and showers for just a few minutes. Wait till the next day and the odor probably will be gone.

captain gort
4 months ago

I always wipe dirty dishes and pans out with paper towels before I wash them. Give the gray tank a break! Sometimes I pour a big shot of liquid dishwasher soap down the drain BEFORE the next leg of a trip and let it slosh around…really cleans it out.

captain gort
4 months ago

I highly recommend the new vent caps that create a suction when the wind blows. I installed them on my gray and black tanks. Also- the black tank flusher option is a MUST. I wish I had one on my gray tank!

4 months ago

Happy campers is also used for gray tank. Love this product and it’s the only one I use

4 months ago

No black tank odor here.
Flush with a lot of water. Then, after flushing, fill toilet again with water, and flush again. That goes for #1 and #2. Mostly water in the tank at that point. Haven’t “backflushed” the tank at all.
Installed a new toilet a few months ago and was dreading the anticipated stink when I pulled the old one. Nope. Barely a wiff.

4 months ago

Our problem is the gray tank Oatey 39012 internal gray tank vents. When they work they’re great, but when they stick open, like after dumping gray tank, it’s horrible. Made us think it was black tank smell. But when galley area was stinking, I found this valve ( 1st of 3), under sink. Washed it out, works for a while, but sticks again really soon. So now just carry extras. I have found & replaced 2 of the 3 in our 2016 Bounder 33c, still haven’t found bedroom 1 for the laundry drain that we don’t have. I know this saved a little plumbing, but they are a pain. Good thing Amazon sells them, & they are available at most hardware stores.