Monday, December 5, 2022


That stink in your RV is probably the unsuspected gray water tank


The tech kept telling me, “That might just be the gray water tank. It can smell as bad as the black.” Actually, at least three or four techs told me that every time I brought up how BAD it smells inside the motorhome when we are traveling. Three of them said to add Pine Power to the tank.

Black water flushing fanatic

I am diligent about flushing out the black water tank. Over and over again until the water runs clear. I am the “flusher” in the family. My husband would not have the patience or perverse delight to watch “it” all go down the drain.

I am also diligent about making sure that we run water down all the drains—sinks and shower—to make sure gases don’t come up a dry trap. We have changed the cheater vents under the sinks, too.

Gray water tank flush

The gray water is another matter, though. At an RV rally, I was introduced to ways to flush the gray water tank. I even had it done professionally! I do that periodically now but, to be fair, not often because it is a major hassle. Here is the method I learned.

After another long text message to our beloved tech, he again said, “It’s the gray water! Gray water!”

Having to ride with the side windows cracked when driving the motorhome so that we wouldn’t keel over was getting old, not to mention a bit cold, so I decided to flush the gray water tank again.

New method to flush the gray water tank

I tried a new method this time. Instead of draining completely when we left the campsite, we kept in about 1/3 of a tank of gray water and added the Pine Power cleaner. Because it kills bacteria, I did not want to use it in the black tank and kill the enzymes that are digesting the toilet paper. Pine Power is not to be confused with Pine Sol. I have been told that Pine Sol contains solvents that can harm the seals. Pine Power is hard to find, though, so when I saw it in an out-of-the-way gas station this summer I bought them out! It can be ordered on Amazon here though, too.


We both realized that after about an hour on the road, there was no smell even though I had forgotten to crack open the windows.

Hmm… It might just be the gray water tank after all.


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1 month ago

We never had problems with smells…until recently after picking up the rig from the repair shop. These were the hottest days of summer, and the rig had been sitting awhile. We had also noticed when we picked it up that someone had been “playing” with the toilet (half a roll of TP laying inside, and some off-colored water in the seal area).

We always flush and clean the tanks after each dump, replace with some new water and drop ins before we even leave. Every so often we do the Calgon/Dawn “down the road” wash. We figured a good “down the road” wash would help. Not so much.

For the next few weeks, we put extra drop-ins into the tank after dumping and driving to another location. Then we began to leave the vent in the bathroom open when we weren’t stopped/set up. After a while the odor disappeared!

We finally decided it may have been a combination of extremely hot temps (boiling black tanks could not smell very nice) and perhaps a poo pile that took time to melt?

1 month ago

Since day one, we’ve used “Happy Camper” in both gray and black tanks. No smell whatsoever from either tank. No stinky artificial cover-up, orange, lemon, pine, or airline lav smells. After dumping, we add one scoop in three gallons of water to each tank, and we’re good to go until the next trip. It’s all natural and that stuff simply works!

BJ Wieland-Doucet
1 month ago

I discovered that too with my stationary rig. About every month or so I use a gray tank “cleaner” I get at Walmart. It says use 1/4 C down a drain, let sit a bit then run water thru the drain. Its supposed to clean the traps & the tank.
I’ve found emptying the tank(s) weekly also helps with the odor.
I also use the baking soda & vinegar clean on the kitcen drains. Keeps them clog free & smelling sweet AND won’t damage the pipes or the tanks. I have 2 gray tanks & 1 black.

Gary Lowe
1 month ago

Changing Lanes YouTube recently had their tanks professionally cleaned. The professionals agreed the grey tank is responsible for the smells.
They do use Pine Sol and commented that it no longer has pine oil, so it’s safe to use.

1 month ago

About every 6 months or so, we put 1/2 bottle in each tank with about a quarter full of water. We’ll travel for the next few days and then dump. No smells for the last 16 years and I hope not for the next 16.

Mara Sievers
1 month ago

Yep. I’ve been telling everyone who would listen: the grey water is way worse than the black water!

1 month ago

How much Pine power do you add to the tank? Whole bottle?

1 month ago
Reply to  Ran

The techs suggested half a bottle but I am frugal and only added about a quarter of a bottle.

1 month ago
Reply to  Nanci

Thanks! I’m gonna try it!

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