Sewage Smells When We flush

[rlh1957]

scroll back up, it is in this post....
Dometic 300 series had the problem
switched to a 320 series and odor gone.

[orabun]

Originally Posted by campers302

Did you get it resolved?

Not totally. It's a lot better though. This has happened every time we start a camping trip, its just never been this bad. I think my tank is mounted low on the door side, opposite from the drain. Even putting it on leveling blocks a little high on the door side, it retains some waste.

[campers302]

Originally Posted by orabun

Not totally. It's a lot better though. This has happened every time we start a camping trip, its just never been this bad. I think my tank is mounted low on the door side, opposite from the drain. Even putting it on leveling blocks a little high on the door side, it retains some waste.

There is only one product that works the best IMHO.

I you have the opportunity rinse your tank by dropping two full toilet bowl of water and then drain it.

Now again drop two full bowls and add one bottle of the product in the link in this message. Now drop one more full bowl and leave it.
Now travel to your camp site, this will have agitated the tank and hopefully loosen all waste. If possible drain your tank on entry to the campground. This will be the only time you will do this drain on entry at a campground. In the future you will hopefully have a clean tank.
All the above was just to get you back to a clean tank.

To maintain a clean tank:
When you arrive at a campground repeat the steps above, 2 drops, bottle of chemical, one more drop and camp and enjoy. If it is very hot you may have to add a bottle as poop is heat sensitive.

From this point forward:
When ever you dump always do the above with two drops and chemical and one drop.
This way if you store your Rv the tank is treated with clean water and chemical. Also it is ready
for the next stop.

Hope this is as clear as mud or better. lol


Hope this helps.


here is the link to the product.

Aqua-Kem RV Holding Tank Treatment - Deodorant / Waste Digester / Detergent - 6x8 oz pack - Thetford 03106 Average rating:5out of5stars, based on4reviews4 reviews Aqua-Kem Walmart # 555402272 $11.47

[SlowrideHD]

I have been camping all my life and have never seen the need to use any sort of fancy chemical "waste digester". Your black tank is a holding tank, not a septic tank. If you keep it flushed and use it and dump correctly, there is absolutely no need to try to treat it as a septic system.
When I dump, I flush and drain as many times as I can. I will gladly stay extra days in a campground to avoid a line at a dump station, or move to a full hookup if available. After my tank is running clean water after dump/rinse, I make sure I am going to travel with about five gallons of water in the black tank. I believe a healthy tank needs to never dry completely out (just my opinion). Then before I pull out, I add a cup of Pinesol and about 1/4 cup of Dawn down the toilet. That sloshes around on the way to the next stop and not only cleans the tank, but helps keep the quantity sensors clean as well. This has worked for me for decades of camping. No odors, no problems.

[dannyabear]

Originally Posted by SlowrideHD

I have been camping all my life and have never seen the need to use any sort of fancy chemical "waste digester". Your black tank is a holding tank, not a septic tank. If you keep it flushed and use it and dump correctly, there is absolutely no need to try to treat it as a septic system.
When I dump, I flush and drain as many times as I can. I will gladly stay extra days in a campground to avoid a line at a dump station, or move to a full hookup if available. After my tank is running clean water after dump/rinse, I make sure I am going to travel with about five gallons of water in the black tank. I believe a healthy tank needs to never dry completely out (just my opinion). Then before I pull out, I add a cup of Pinesol and about 1/4 cup of Dawn down the toilet. That sloshes around on the way to the next stop and not only cleans the tank, but helps keep the quantity sensors clean as well. This has worked for me for decades of camping. No odors, no problems.

THIS is such a hard concept for some to understand!!!!!!!!!!!!!!

[Jakieboy]

Before we graduated to a TT with built-in black tank flush, we used an accessory sprayer that screwed on to the end of a garden hose to flush the black water tank. Before leaving camp, I would thread the garden hose in through the door to the bathroom, attach the sprayer, and help my wife lower it into the black water tank. I would then go outside to the fresh water nozzle and turn on the sprayer. That process worked for us for many years before we upgraded to newer RV's.

Nowadays, we always leave a few gallons of water in each waste tank, black and grey, before we head home or to the next campsite. We dose the black water tank with commercial deodorant, and each grey water tank with PineSol or other detergent. The sloshing around in all the tanks while we are driving really helps to dislodge contaminants in each tank, especially wads of toilet paper, by the time we reach our next destination.

[archer314]

From what I was reading earlier today,,it was the Dometic 300 that was holding pee water in a gap,,there was a picture up but cant find it now, they replaced toilet and the odor is gone

[tomm1947]

Most if not all units have a vent pipe from the black water tank thru the roof to exhaust some of those smells. There's usually a cap over the top of the pipe to keep birds & other critters from making nests & such. The vent is usually 1&1/2" to 2". But you have to realize that the toilet of your unit doesn't have a trap like houses do, so every time you flush you have a 3 to 4 inch hole directly into the black water holding tank. There are all kinds of holding tank treatments to help with the smell. Most do a marginal job of masking or covering up the smell. God Luck!

[Beauty and Beast]

What HangDiver said. Make sure you are not running the exhaust fan when you flush. It will suck the fumes up past the ball valve when you open it to flush.

[TitanMike]

Originally Posted by SlowrideHD

I have been camping all my life and have never seen the need to use any sort of fancy chemical "waste digester". Your black tank is a holding tank, not a septic tank. If you keep it flushed and use it and dump correctly, there is absolutely no need to try to treat it as a septic system.
When I dump, I flush and drain as many times as I can. I will gladly stay extra days in a campground to avoid a line at a dump station, or move to a full hookup if available. After my tank is running clean water after dump/rinse, I make sure I am going to travel with about five gallons of water in the black tank. I believe a healthy tank needs to never dry completely out (just my opinion). Then before I pull out, I add a cup of Pinesol and about 1/4 cup of Dawn down the toilet. That sloshes around on the way to the next stop and not only cleans the tank, but helps keep the quantity sensors clean as well. This has worked for me for decades of camping. No odors, no problems.

A lesson I learned from my dad about 70 years ago. " If you want to get rid of an odor, get rid of what's causing it."

Like you said, travel with some clean water in the black tank rather than just dumping and leaving it empty.


If one can't dump when they leave the campground/campsite fill the tank with water so it's at least 3/4 full. Travel motion will keep solids in suspension rather than turning to a layer of "mud" on the bottom. When this happens it's just like when the tide goes out at the mouth of a river. Water will first start flowing out the valve and as tank empties a channel is formed in the sludge that's been just sitting there.

Something I haven't read yet on this forum but it was frequently mentioned on another RV forum, often the largest source of stench is the top of the tank. If it has any "organic matter" splattered on it, and it's not cleaned off regularly, it just sits there and decomposes releasing odors. This is why lots of water in in the tank before dumping as well as a good flush before closing the dump valve. If no tank flusher built in (or not working) then use a wand type tool connected to a water hose.

As for chemicals? I use Odorlos. Does a great job of keeping down the "Potty Smell" that's inevitable when using a holding tank system, even a super clean one.

[AceCombat]

Has it been windy where you are. If so the wind could be giing down the vent stack and when you flush you get a little puff of not mountain or countey air! Or if your camping in an open area you might get more breeze over the vent stack.

[orabun]

It's cleared up now. Thanks for all y'alls help.

[Tundra 2014]

A lot of great suggestions. Wall-Mart used to carry a Camco flexible toilet hose w/ spray head that did a pretty good job of cleaning my sensors and getting odor out of camper that had set. Once you get it under control, start using something like Happy Camper after every trip with a couple of gallons of water in all tanks. Basically water softener to keep stuff from sticking to tank sensors and walls.

[Jomo]

Get you a bowl chock from Walmart or Amazon or an Rv store it goes into the commode so the water runs. As far as the tank goes i use bleach and dawn

[Trobec]

I had a bad smell from my toilet once. Took me a day to figure it. I have tank heaters and for some reason the switches for them are close to the floor. My dog would lay down on the floor with his back against the wall and it would turn the switches on. 80 degrees and thank heaters make for a nasty smelling rig!lol

[Jerry D]

Just a suggestion regarding possible cures for sewage smell. All of prior suggestion a very good and we have had occasion to use them. But it occurs to me that a clogged toilet air vent could also be a problem. What say you all.

[ARICE]

Originally Posted by orabun

You know, I didn't think about it, but I had both a/c's running so it could have been pulling gases out!!! Thanks for your help.

No the ACs are not causing that and really an exhaust fan won't either unless you stand there with the pedal to the floor for 10 minutes and even then, with a maintained tank, I don't think it would do it.
Have you checked your vents? Sounds like a vent blocked and not allowing the gas to escape.
No matter what you do, if a vent is blocked your going to have the same issue after a day or two cleaning.

[B. R. Mullen]

First we had new trailer every time we flushed smell came into trailer through air conditioner cuss they didn't tape over edges and was sucking it in to trailer once taped up edges it quit. 2nd you can buy a back flush valve to back wash your black water tank lot safer then hose in camper works better 3, 4 times should be cleaned out. Good luck

[A32Deuce]

Tank heaters don't come on over 40 degrees.

[Seamule]

My 2018 Roo 23BDS has the Dometic 300. I was going crazy trying to find the odor. Brand new camper with sewage smell...something is not right. After many searches on the net, you tube had the answer. My plastic Dometic 300 is cracked and retaining waste in the toilet housing. Not leaking on the floor. I threw a tank bomb behind the toilet in an opening to help make it through the trip. I ordered the Dometic 320 porcelain elongated bowl to replace it along with the Siphon 360 roof vents just for good measure. Going camping again in 2 weeks and I can’t wait to change it! I have used the 320 before and loved it! Everything fits LOL!!!