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Old 04-11-2024, 09:30 AM   #1
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Black Tank Odor

Good Morning,

I know this is an old topic but I can not get rid of black tank odor. I have tried Calgon water softener, Dawn dish soap, Unique liquid, drop in powder packets, etc. I have recently run across on the internet Siphon 360 valve to place on the vent on the roof. Does anyone have experience with this product?
Any other suggestions?

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Old 04-11-2024, 09:40 AM   #2
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Originally Posted by RMHarville View Post
Good Morning,

I know this is an old topic but I can not get rid of black tank odor. I have tried Calgon water softener, Dawn dish soap, Unique liquid, drop in powder packets, etc. I have recently run across on the internet Siphon 360 valve to place on the vent on the roof. Does anyone have experience with this product?
Any other suggestions?

Wildwood Heritage Glen 22RBHL
Ford 250 2012 pickup

Thank YOU
We thought we had black tank odor that couldn't be squashed but it turns out, it was gray tank odor. I changed air admittance valves for both the kitchen gray and shower/bathroom sink gray and solved our problem.
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Old 04-11-2024, 10:17 AM   #3
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Few topics are more hotly contested, and there's lot of opinions. This is just my .02....

First, I'd look VERY carefully at your gray tank (as gray tank odors can easily mask as black tank odors). I'd also take a look at your toilet - older plastic units (like the Dometic 300) can crack and have a design that holds urine in a channel. Upgrading to the ceramic Dometic 310 or better (check clearances) will resolve this. Also check your venting for both black and gray - the chimneys and air inlet valving - to make sure it's not blocked (for instance, wasps LOVE to make nests and cause troubles for RV'ers).

But if it's truly your black tank, I'd suggest a DEEP clean, and then potentially a new approach to your waste tanks.

1. Deep Clean
Take this pre-season time to do a deep clean and sanitize run for your **entire** water system (including waste water and all tankage). RV holding tanks AREN'T septic systems, and aren't necessarily designed to harbor a colony of good bacteria to break down waste. RV fresh water tankage is usually cleaned with a bleach solution of 1/4c:~15gal. So, for a `60 gal tank, that'd be ~1 cup of bleach in a full tank. Run through the entire water system till you smell bleach at every outlet and let it sit 12 hours (better is overnight). Then drain and flush till you don't smell bleach at any output point anymore.

However, for more disinfecting power (and to deal with the bacteria that's making your bad smells), you can mix up stronger batches. Chlorox lists formulas for 1500ppm (1:48) and 2000ppm (1:36) mixes (which are both WAY more stronger than the typical RV drinking water ratio above):

https://www.clorox.com/learn/bleach-...n-ratio-chart/

I'm not sure of the year of your Heritage Glen, but the current year has tankage of: FRESH WATER - 49 gal.. GRAY WATER - 62 gal., and BLACK WATER - 32 gal.

Let's round everything for easy math:

FRESH WATER - ~50 gal.
GRAY WATER - ~60 gal.
BLACK WATER - ~30 gal.

FRESH water tank: RV standard sanitize: 1/4 cup for 15 gallons = .833 cup for 50 gal. Better safe than sorry, to I'd use a cup for your 50 gallons and be done with it.

BLACK and GRAY tanks: I wouldn't necessarily go Seal Team Six on these tanks, but - since you're having an issue - I'd step up to the 1500ppm version. This will still mean a lot of bleach (and a lot of bleach smell), but it will get the job done.

GRAY WATER - ~60 gal @ 1:48 = 1.25 gal of bleach. So you need to get 1 gallon + 1 quart of plain Chlorox bleach into the gray tank (eg, through your kitchen sink) and then chase it with 60 gal of fresh water.

BLACK WATER - ~30 gal @ 1:48 = .625 gal of bleach = 10 cups of plain Chlorox bleach down your toilet, chased with 30 gallons of water.

Let sit at least 12 hours (better 24) to kill everything in the tank and then drain. Chase with fresh water to reduce some of the leftover bleach smell (and there mostly likely will be some).

Ultimately, if you hold waste in your tanks for any length of time, you're going to want to support some aerobic bacteria. Bleach kills most everything, so we need to make an environment suitable to let good bacteria live and knock down bad bacteria that feed on the waste and cause your stink. So....


2. New Approach
Now that you've reset your tankage, I am a BIG believer in TR Bowlin's Bio-Geo method. Starting with dry tanks, add a good slug of water, plus boraxo and - to the gray tank, orange degreaser (I use Zepp); to the black tank, grease breaking dish soap (I use name brand Dawn). This is as easy as remember to add both (water + Boraxo + Zepp to the gray tank, water + Boraxo + Dawn to the black) at the start of any tank (or after dumping).

This has worked very well for us, and we've got very sweet tanks that we use and have had no problems with.

Again, just my .02. Hope this helps.
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Old 04-11-2024, 10:30 AM   #4
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Originally Posted by Rhumblefish View Post
Few topics are more hotly contested, and there's lot of opinions. This is just my .02....

First, I'd look VERY carefully at your gray tank (as gray tank odors can easily mask as black tank odors). I'd also take a look at your toilet - older plastic units (like the Dometic 300) can crack and have a design that holds urine in a channel. Upgrading to the ceramic Dometic 310 or better (check clearances) will resolve this. Also check your venting for both black and gray - the chimneys and air inlet valving - to make sure it's not blocked (for instance, wasps LOVE to make nests and cause troubles for RV'ers).

But if it's truly your black tank, I'd suggest a DEEP clean, and then potentially a new approach to your waste tanks.

1. Deep Clean
Take this pre-season time to do a deep clean and sanitize run for your **entire** water system (including waste water and all tankage). RV holding tanks AREN'T septic systems, and aren't necessarily designed to harbor a colony of good bacteria to break down waste. RV fresh water tankage is usually cleaned with a bleach solution of 1/4c:~15gal. So, for a `60 gal tank, that'd be ~1 cup of bleach in a full tank. Run through the entire water system till you smell bleach at every outlet and let it sit 12 hours (better is overnight). Then drain and flush till you don't smell bleach at any output point anymore.

However, for more disinfecting power (and to deal with the bacteria that's making your bad smells), you can mix up stronger batches. Chlorox lists formulas for 1500ppm (1:48) and 2000ppm (1:36) mixes (which are both WAY more stronger than the typical RV drinking water ratio above):

https://www.clorox.com/learn/bleach-...n-ratio-chart/

I'm not sure of the year of your Heritage Glen, but the current year has tankage of: FRESH WATER - 49 gal.. GRAY WATER - 62 gal., and BLACK WATER - 32 gal.

Let's round everything for easy math:

FRESH WATER - ~50 gal.
GRAY WATER - ~60 gal.
BLACK WATER - ~30 gal.

FRESH water tank: RV standard sanitize: 1/4 cup for 15 gallons = .833 cup for 50 gal. Better safe than sorry, to I'd use a cup for your 50 gallons and be done with it.

BLACK and GRAY tanks: I wouldn't necessarily go Seal Team Six on these tanks, but - since you're having an issue - I'd step up to the 1500ppm version. This will still mean a lot of bleach (and a lot of bleach smell), but it will get the job done.

GRAY WATER - ~60 gal @ 1:48 = 1.25 gal of bleach. So you need to get 1 gallon + 1 quart of plain Chlorox bleach into the gray tank (eg, through your kitchen sink) and then chase it with 60 gal of fresh water.

BLACK WATER - ~30 gal @ 1:48 = .625 gal of bleach = 10 cups of plain Chlorox bleach down your toilet, chased with 30 gallons of water.

Let sit at least 12 hours (better 24) to kill everything in the tank and then drain. Chase with fresh water to reduce some of the leftover bleach smell (and there mostly likely will be some).

Ultimately, if you hold waste in your tanks for any length of time, you're going to want to support some aerobic bacteria. Bleach kills most everything, so we need to make an environment suitable to let good bacteria live and knock down bad bacteria that feed on the waste and cause your stink. So....


2. New Approach
Now that you've reset your tankage, I am a BIG believer in TR Bowlin's Bio-Geo method. Starting with dry tanks, add a good slug of water, plus boraxo and - to the gray tank, orange degreaser (I use Zepp); to the black tank, grease breaking dish soap (I use name brand Dawn). This is as easy as remember to add both (water + Boraxo + Zepp to the gray tank, water + Boraxo + Dawn to the black) at the start of any tank (or after dumping).

This has worked very well for us, and we've got very sweet tanks that we use and have had no problems with.

Again, just my .02. Hope this helps.
Good information and procedures.

Bob
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Old 04-11-2024, 10:44 AM   #5
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Originally Posted by Mr. Dan View Post
We thought we had black tank odor that couldn't be squashed but it turns out, it was gray tank odor. I changed air admittance valves for both the kitchen gray and shower/bathroom sink gray and solved our problem.
X2

Question though on cleaning the holding tanks. If they are sealed correctly how does the smell get into the camper? Maybe on a stagnant day when the odor from the rooftop vent happens to drift down? I haven't come across that yet though. I've even done the "dreaded" flush with the vent fan running, the toilet valve is not open long enough to bring the smell up. At least not in my camper.

Experiment: Pee in your toilet one time and don't flush. Come back two hours later and open the lid. Phew!!!!

So in my opinion as soon as you use your holding tank the first time it will stink again. Why clean them as long as they are dumping good?
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Old 04-11-2024, 11:17 AM   #6
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X2

Question though on cleaning the holding tanks. If they are sealed correctly how does the smell get into the camper? Maybe on a stagnant day when the odor from the rooftop vent happens to drift down? I haven't come across that yet though. I've even done the "dreaded" flush with the vent fan running, the toilet valve is not open long enough to bring the smell up. At least not in my camper.

Experiment: Pee in your toilet one time and don't flush. Come back two hours later and open the lid. Phew!!!!

So in my opinion as soon as you use your holding tank the first time it will stink again. Why clean them as long as they are dumping good?
Again as many have said before, it is a HOLDING TANK and not a septic system. I recommend using a generous amount of water to rinse the tanks after dumping. Then dump again. We add about a 1/2 cup of Pine Sol to each grey and black tank after flushing or dumping the tanks.

Bob
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Old 04-11-2024, 11:33 AM   #7
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What golfingdave said

Clean your toilet seal then You can even use a small smear of plumbers grease on it to make sure it is a good seal add some water to the bowl after each flush
Fast flushes I have a plastic drink glass at the sink to add water to bowl instead of trying to use pedal
Don’t have the exhaust fan on in the bathroom it can pull air up from the yukky tank

Check your sink in the bathroom too as they sometimes connect to black tank
Make sure it has water in P trap
Test it by f
Plugging up sink and add some water
If smell goes away you at least know where to fix
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Old 04-11-2024, 11:39 AM   #8
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Make sure there is water in the P traps at the sink and at the lavatory. Also, the shower if it has a P trap or it may have a HepVo valve that is stuck or obstructed and held open by hair and residue.

Bob
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Old 04-11-2024, 12:26 PM   #9
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Again as many have said before, it is a HOLDING TANK and not a septic system. I recommend using a generous amount of water to rinse the tanks after dumping. Then dump again. We add about a 1/2 cup of Pine Sol to each grey and black tank after flushing or dumping the tanks.
That doesn't answer my question though(if you agree a tank will start smelling as soon as you use it) of how does cleaning a tank keep any smell from getting into the interior if everything is sealed as it should be.
Traps are a seal in my opinion.

Being a holding tank has nothing to do with smell or not. If a septic tank was not sealed properly(such as water in traps) your house possibly could start to stink. I admit I am not taking into account the leach field here. That probably comes into the equation somehow.
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Old 04-12-2024, 05:20 AM   #10
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Also, there was a post within the last year that the vent pipe going to the roof had come loose from the tank and that was causing the odor.
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Old 04-20-2024, 02:39 PM   #11
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That swirling spray hose for the black tank, just let it rip for minutes. For grey, just some dawn. I will use a gallon of white vinegar in each tank to help clean sensors. Letting it sit full a few days. Then use the drop in sanitizer with bio goodies for storage plus a few gallons.
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Old 04-20-2024, 04:17 PM   #12
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Originally Posted by GolfingDave View Post
X2

Question though on cleaning the holding tanks. If they are sealed correctly how does the smell get into the camper? Maybe on a stagnant day when the odor from the rooftop vent happens to drift down? I haven't come across that yet though. I've even done the "dreaded" flush with the vent fan running, the toilet valve is not open long enough to bring the smell up. At least not in my camper.

Experiment: Pee in your toilet one time and don't flush. Come back two hours later and open the lid. Phew!!!!

So in my opinion as soon as you use your holding tank the first time it will stink again. Why clean them as long as they are dumping good?
If it's hot enough, and you aren't using double dose of chems, all it took was a quick flush of the toilet for noxious fumes to rise up out of the tank to bowl you over, I nearly made a Wiley Coyote hole in the door running out of the camper. HEAT after a few days makes a toxic brew. Those conditions required more frequent dumping/flushing, or more chems.
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Old 04-20-2024, 05:00 PM   #13
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If it's hot enough, and you aren't using double dose of chems, all it took was a quick flush of the toilet for noxious fumes to rise up out of the tank to bowl you over, HEAT after a few days makes a toxic brew.
I guess I have been lucky. Midwest summers, full time, no chemicals or cleaning of tanks(dump and go) and have not ever had a fume problem. Even with the exhaust fan on and flushing.

I will admit though now, just a few days ago I had a faint smell for the first time. Cleaned the floor, walls, shower door and toilet inside and out and it was gone. Nothing extreme, just spray and wet with some cleaner and wiped down.

My kitchen sink stinks worse than the bathroom but that is from putting the cover on before it dries, it gets that musty smell when I do that.
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Old 04-20-2024, 05:23 PM   #14
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Fake Questions

Does it bother anyone that people join, leave a complex question that requires a lot of detailed answer, and they never return again? This Question was posted the 11th and the OP has not been back on the forums since.



I love the information, great know as a newbie myself, but in these days of "Swatting", this just bothers me.



Sorry, end of rant!
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Old 04-20-2024, 08:55 PM   #15
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I guess I have been lucky. Midwest summers, full time, no chemicals or cleaning of tanks(dump and go) and have not ever had a fume problem. Even with the exhaust fan on and flushing.

I will admit though now, just a few days ago I had a faint smell for the first time. Cleaned the floor, walls, shower door and toilet inside and out and it was gone. Nothing extreme, just spray and wet with some cleaner and wiped down.

My kitchen sink stinks worse than the bathroom but that is from putting the cover on before it dries, it gets that musty smell when I do that.
I can tell you for sure that our exhaust fan is our entire issue in our rig. If you step on that toilet flusher with the fan on toucan feel the wind come out of the tank.
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Old 04-20-2024, 09:05 PM   #16
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Does it bother anyone that people join, leave a complex question that requires a lot of detailed answer, and they never return again? This Question was posted the 11th and the OP has not been back on the forums since.



I love the information, great know as a newbie myself, but in these days of "Swatting", this just bothers me.



Sorry, end of rant!
Very common on all internet forums.
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Old 04-20-2024, 09:40 PM   #17
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As I stated earlier, we just add a cup of Pine Sol to the grey and black tanks. No odor issues.

Although sometimes after a flush, the immediate area smells like someone crapped a Christmas tree.

Bob
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Old 04-21-2024, 09:21 AM   #18
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Originally Posted by GolfingDave View Post
I guess I have been lucky. Midwest summers, full time, no chemicals or cleaning of tanks(dump and go) and have not ever had a fume problem. Even with the exhaust fan on and flushing.

I will admit though now, just a few days ago I had a faint smell for the first time. Cleaned the floor, walls, shower door and toilet inside and out and it was gone. Nothing extreme, just spray and wet with some cleaner and wiped down.

My kitchen sink stinks worse than the bathroom but that is from putting the cover on before it dries, it gets that musty smell when I do that.
It was actually a midwest summer that got me that day! We were at the Goshen, IN FROG rally a few years ago, it was in the 90s every day, and oppressively humid. I think it was day 4 of that constant heat that did it. Had already dumped the grey, but black was only half full, so had planned on waiting till it was full. Was rolling my eyes thinking wife must be exaggerating how bad it was. She wasn't. Now I know when it's that hot, double the orange syrup! It's a 30g tank, so doesn't require much syrup anyway, even doubling it.
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Old 04-21-2024, 09:22 AM   #19
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As I stated earlier, we just add a cup of Pine Sol to the grey and black tanks. No odor issues.

Although sometimes after a flush, the immediate area smells like someone crapped a Christmas tree.

Bob
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Old 04-21-2024, 09:26 AM   #20
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Does it bother anyone that people join, leave a complex question that requires a lot of detailed answer, and they never return again? This Question was posted the 11th and the OP has not been back on the forums since.



I love the information, great know as a newbie myself, but in these days of "Swatting", this just bothers me.



Sorry, end of rant!
Yes. If I don't see that the OP has come back since the day he posted, I try to point that out as well so people stop trying to help the ungrateful post and run types. But now we are just BSing. Emphasis on the S.
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