black water tank smell

[nextlevel]

About this time last year I purchased a 2011 Puma 38PFSKB. I am still having problems with sewer smell in the black water tank. Let me state what I have done:
1. Replaced the old Thetford toilet with an upgrade.
2. Thoroughly cleaned the tank several times.
3. I have used Happy Camper water treatment.
4. After I clean the tank I put some water in it and put in some treatment. After maybe two weeks the tank gets close to full but it begins to smell real bad when I flush the toilet. I live in this RV.
5. I am connected to a septic tank so all I have to do is pull the valve to empty the tank.
6. I have checked the vent pipe several times.
7. I do not put any tissue in the tank. I have a flip top trash can with a bag and I put the tissue in the can with a deodorizer. Never have a problem with the trash can smelling.

I just need to know what to do about the bad smell. After emptying the tank the smell goes away for about another two weeks. I thought the treatment was suppose to help with the order.

[Grit_dog]

" Doc, everytime I do this, it hurts!"
Doc, "Don't do that anymore..."

Black tank stinks only when getting close to full for a year and you haven't thought of changing the routine to dump when less full?

It's pretty normal. If we get a fairly full poop tank, in the summer, and then give it a good agitation (i.e. Driving a distance with the tank full), it freakin stinks.
Presume your camper is parked, but same thing. Likely gets full enough to block the vent or something.

[Grit_dog]

GrandpaKip wrote:

trail-explorer wrote:

nextlevel wrote:
7. I do not put any tissue in the tank. I have a flip top trash can with a bag and I put the tissue in the can

EEEWWWWW... that is just disgusting.

That’s done all over in the Caribbean and Mexico. Really doesn’t smell. Toilet paper clogs a lot of sewer systems down there.

People dig holes and cr ap in the dirt too....doesn't make it the best way to take a dump!

[hawkeye-08]

The advice about waiting until it is full before dumping was only half the story. The other half is to not leave the dump valve open on black tank or you will have problems. So, answer is, close black tank dump valve until you are ready to dump, be it after a 3 day weekend or whatever. Make sure there is plenty of water and dump away. Close valve when done until next time you want to dump.

If you want to see what happens when you leave your black tank dump valve open, proceed with caution and make sure you have plenty of time allowed for showering and clean after you unplug that mess. Had a friend not understand this and he left his black dump valve open, backed up one night when it was raining, I don't think he ever did get the stinky slinky cleaned out, I think he replaced it.. It was several days of messing with the mess and boy did it stink around their trailer...

It is a holding tank and if the valve is left open, eventually, the liquids drain out leaving solids. It depends on usage and the plumbing, but it will happen.

My wife and I camped in the front yard of a house one of our kids was buying, dumped at dump station on way home (only parked there 4 nights so tank not very full.

[GrandpaKip]

trail-explorer wrote:

nextlevel wrote:
7. I do not put any tissue in the tank. I have a flip top trash can with a bag and I put the tissue in the can

EEEWWWWW... that is just disgusting.

That’s done all over in the Caribbean and Mexico. Really doesn’t smell. Toilet paper clogs a lot of sewer systems down there.

[trail-explorer]

nextlevel wrote:
7. I do not put any tissue in the tank. I have a flip top trash can with a bag and I put the tissue in the can

EEEWWWWW... that is just disgusting.

[wnjj]

secretcheese3000 wrote:

Lynnmor wrote:
If you leave the gray tank valve open, then any leakage from the air admittance valve will have a full time stink coming from the septic tank.

Can you tell me more about the air admittance valve? I thought the grey and black tanks were unconnected except for being drained from adjacent valves. But now we have a sudden and mysterious black tank smell after six years of full-timing. How does the black tank smell get into a greywater air admittance valve when the grey valve is left open?

We dump 2/3 full and run a Lil Stanker inline vent on the black tank. Weve had zero trouble until the grey valve was left open continuously. I just don't understand how the smell from one system gets into the other system. I thought the dump valve manifold separated the two completely. What am I missing?

If you are leaving your dump hose connected and the gray valve open, your entire gray system can potentially vent the sewer/septic system you’re connected to, not your black tank. If the air admittance valve is leaking, that foul air will enter your RV. Leave the gray valve closed and dump it frequently too or as was suggested create a P-trap in the hose to block the airflow.

[opnspaces]

I 2nd, 3rd, or maybe even 4th the posts above.

1. You can really dump at almost any time. The common advice given on here is fill it to 3/4 tank before dump. But you can go to half tank and it won't be any worse for draining.
2. It's a tank full of poo, there's no real benefit to cleaning it; Especially if it's in constant use like yours, and not sitting for a week before uses.
3. Make sure the vent fans are off before you flush.
4. Check or just replace the air admittance valves. See link in post above.
5. Add more chemical if it starts to stink. Though I somehow don't think this will solve your problem.
6. There's no benefit to keeping the paper in a can. The tanks are smooth sided and the paper will just flow out with everything else, go ahead and flush it.
7. RV specific toilet paper is a waste of money.
8. You can use whatever septic safe paper you want. I use Costco Kirkland brand and have not had a problem in 13 years.
9. See the link below to this guys videos about dumping. They're entertaining and informative.

Link

[opnspaces]

secretcheese3000 wrote:

Can you tell me more about the air admittance valve? I thought the grey and black tanks were unconnected except for being drained from adjacent valves. But now we have a sudden and mysterious black tank smell after six years of full-timing. How does the black tank smell get into a gray water air admittance valve when the grey valve is left open?

You are correct that the two tanks are not connected. But the gray tank can be just as stinky as the black tank. If you look under your sinks you'll see a T in the drain that goes up to what looks like a cap. That is you air admittance valve, Unscrew the valve and it should only allow air to flow in one direction, down into the tank. If it's faulty or if you're not sure, spend the $7 to replace it.

Link

[spoon059]

Ummm... used toilet paper in the trashcan in the bathroom? Wouldn't that cause a bad odor? This is the very first adjustment that I would make. IF you are doing everything right, toilet paper is perfectly fine in your toilet.

The key things to check...
#1 is the toilet bowl holding water? The water seal will prevent toilet odors.
#2 the black tank vent. Not sure how to check, but you need to make sure that the bottom of your black tank vent is exposed to AIR in the tank, not soiled water. Then you need to make sure that your black tank vent is venting and not obstructed.
#3 air admittance valve under the sink. Most RV sinks aren't vented up and out like traditional plumbing. There is a burp style vent under the sink. Check to see if odor is coming from that.

[secretcheese300]

Lynnmor wrote:
If you leave the gray tank valve open, then any leakage from the air admittance valve will have a full time stink coming from the septic tank.

Can you tell me more about the air admittance valve? I thought the grey and black tanks were unconnected except for being drained from adjacent valves. But now we have a sudden and mysterious black tank smell after six years of full-timing. How does the black tank smell get into a greywater air admittance valve when the grey valve is left open?

We dump 2/3 full and run a Lil Stanker inline vent on the black tank. Weve had zero trouble until the grey valve was left open continuously. I just don't understand how the smell from one system gets into the other system. I thought the dump valve manifold separated the two completely. What am I missing?

[beemerphile1]

It is a tankful of waste, it should stink. When the toilet is flushed there is an open pathway between you and that stinky stuff.

There should be no smell anytime other than when flushing. The brief moment of flushing is likely to release some stench, due to the design of the system.

Make certain your exhaust fan is off when flushing to minimize the release of odors.

[Bobbo]

nextlevel wrote:
I don't keep water in the gray water tanks being that I am hooked up to a septic tank.

Since it only happens when the black tank is nearly full, this isn't your problem, this time. However, be sure you have put a "U" shaped trap in your dump hose to hold water to keep the septic tank smells from coming back into your gray tank, and possibly into your trailer. It also keeps insects that may be living in the septic system from infesting your gray tank. (The insects are a problem in sewer systems, I don't know about septic systems.)

[ken56]

You stated that it only starts to smell when the tank is near full so that may be because the vent tube is being covered by the water/sewage level and not able to vent. Without putting a camera down there to see if the vent tube protrudes into the tank by any amount we are just guessing here.

Also, pick up a water wand for flushing the tank from the toilet end. I use one and it does help remove more debris than just gravity flow.

[sgfrye]

i vote for dumping more often.

i never dump our black tank before its full. we are weekend warriors so we never fill it while camping. im lucky to have a cleanout on our septic tank at home so i usually wait and dump when we get home.

i use a garden hose from our water spigot at home and finish filling black tank with water straight down the toilet with foot valve open until its totally full before i dump.

then i use the garden hose and wand style tank flusher to flush and dump again.