Black Water Smell Under Sinks

[Keith W.]

Hello-
Newbie to the RV world and looking for advice. We have a GD Imagine 2800BH. The very first trip we plugged up the black water tank since my kids used diaper wipes in the toilet and I couldn't dump it. I drove with a full black water (BW) tank for about 5 hours and it created a horrendous odor throughout. I was able to clear the BW tank, and majority of the smell, but I continue to have some odor coming from under the bathroom & kitchen sinks. Someone told me to change out the plug/cap for the vent line under the bathroom sink as they typically fail. The thought was that odor was seeping out through the cap. However, it has not helped.

I'm concerned that when the BW tank was full and I drove 5 hours, it backed up into the vent line and now dried out. Has anyone ran water down their vent lines on the roof to clear them? Based on your experience, is some odor during the hot summer month's typical? Any input is helpful as I'm concerned the BW seeped somewhere that I can't find.

Side Note: We do have chemicals in the BW tank for odor, but I still have some odor. Also, we fill the BW tank 2/3 full before flushing it each time as I heard that will help clean the tank. Thank you.

[WhittleBurner]

Try a few full back flushes then let it sit full with some bleach...be sure there is no chemicals residue left. Bleach and formaldahyde do not play nice together.

Some odor is not unusual, I suggest no diaper wipes in the system. As you found out they are not as septic safe as advertised.

[boyscout]

Newbie to the RV world and looking for advice. We have a GD Imagine 2800BH. The very first trip we plugged up the black water tank since my kids used diaper wipes in the toilet and I couldn't dump it. I drove with a full black water (BW) tank for about 5 hours and it created a horrendous odor throughout. I was able to clear the BW tank, and majority of the smell, but I continue to have some odor coming from under the bathroom & kitchen sinks. Someone told me to change out the plug/cap for the vent line under the bathroom sink as they typically fail. The thought was that odor was seeping out through the cap. However, it has not helped.

Did the things you replaced under the kitchen and bathroom sinks look like this?

https://www.homedepot.com/p/STUDOR-1...dalType=drawer

That's the recommended replacement for the cheap and fail-prone valves that GD installs. The "someone" who told you to replace them was not necessarily wrong. Those valves if malfunctioning can allow air from the kitchen and bathroom gray tanks, respectively, to come up into the cabinets under the sinks. Gray tanks can get really stinky, just as bad as and not dissimilar to the odor from black tanks.

I'm concerned that when the BW tank was full and I drove 5 hours, it backed up into the vent line and now dried out. Has anyone ran water down their vent lines on the roof to clear them? Based on your experience, is some odor during the hot summer month's typical? Any input is helpful as I'm concerned the BW seeped somewhere that I can't find.

Possible, but the black tank usually vents up to the roof and you don't normally smell what's inside that vent pipe. I'm afraid that it's more likely that something has leaked from connections on the tank - connections for the vent pipe, the main pipe from the toilet, the sensors. It wouldn't take a whole lot of leakage to leave a stink-mess on the tank and/or on top of the coroplast (corrugated plastic sheet) under your trailer. Smells from down there will be inclined to drift up through the holes under cabinets drilled for your sink plumbing lines.

It's probably worth checking for this by looking at the coroplast - is it sagging a lot? - and pushing up on it to test if there is water laying on it. Careful; if there is liquid there it may come out the side where you're laying.

If there's no liquid there then you probably haven't had much leakage and the stink should fade in a few days (but you may still have a leaking problem that should be investigated). If there is liquid on the coroplast there's a messier job there for someone - an insulation layer has been inundated too - and the urgency of finding the leak is higher.

Side Note: We do have chemicals in the BW tank for odor, but I still have some odor. Also, we fill the BW tank 2/3 full before flushing it each time as I heard that will help clean the tank. Thank you.

There are enzyme packets for RV tanks which may help dissolve what's in there. A few people have used Pinesol. Some use Dawn dish soap and water softener. Regardless of what's used, keeping five or more gallons of water in the tank at all times helps prevent stuff building up in the tank. The gray tanks should not be ignored in this regard - as I said they can get really stinky too - so also add cleaning agents and five or more gallons of water to those tanks.

Good luck.

[Longshhm]

Help, please.
Took delivery on a Reflection 295RL on May 29, 2020. We have now developed a problem that we can’t live with.
When we flush the toilet, we get black tank odors in several locations - the bathroom, the cabinet nearest the toilet (where the control center is located), and outside the RV near the steps. Has anyone encountered anything similar, or does anyone have an idea what may be going on?
I’ve checked the vent on top of the RV, and the vent pipe appears to be open, but there’s not much smell coming from it. I tried to see if any water was collecting on the Coroplast by opening a couple of small holes, and found nothing that way.
Any help would be appreciated. I’ll probably be taking it to the dealer, but their service department isn’t exactly the leading edge in knowledge and service.

[Dick Noble]

There may be a black mold problem. A bleach solution ( in all tanks let it set overnight and then rinse the heck out of it) may help. I will once in a while put the blue deodorizer in the grey tank(s) as well as the black tank. . Good luck -- you are going to need it.

[Dick Noble]

One more thing -- I once had the black tank overflow on to a floor. I had to use a bleach solution ( about half and half) and clean everything, including behind the basement wall and under the stairs.

[boyscout]

There may be a black mold problem. A bleach solution ( in all tanks let it set overnight and then rinse the heck out of it) may help. I will once in a while put the blue deodorizer in the grey tank(s) as well as the black tank. . Good luck -- you are going to need it.

One more thing -- I once had the black tank overflow on to a floor. I had to use a bleach solution ( about half and half) and clean everything, including behind the basement wall and under the stairs.

@Keith W. if you find evidence of spillage or mold then bleach will help, but a 50/50 solution is far stronger than is required or advisable. A 10% solution is considered very strong, and a 5% solution enough to do most jobs. Unless the bleach you buy is already diluted (some are, read the label) then use it more sparingly.

Good luck. Please report back here with whatever you figure out, so that someone else coming along later with a similar problem can find it.

[boyscout]

Help, please.
Took delivery on a Reflection 295RL on May 29, 2020. We have now developed a problem that we can’t live with.
When we flush the toilet, we get black tank odors in several locations - the bathroom, the cabinet nearest the toilet (where the control center is located), and outside the RV near the steps. Has anyone encountered anything similar, or does anyone have an idea what may be going on?
I’ve checked the vent on top of the RV, and the vent pipe appears to be open, but there’s not much smell coming from it. I tried to see if any water was collecting on the Coroplast by opening a couple of small holes, and found nothing that way.
Any help would be appreciated. I’ll probably be taking it to the dealer, but their service department isn’t exactly the leading edge in knowledge and service.

Wow, suddenly a few of these complaints in brand-new trailers. I wonder if Grand Design has made an "improvement" to their manufacturing processes.

Your report of odor "outside the RV near the steps" suggests a higher likelihood of leakage on the top (vent or toilet fittings) or side (sensors or black flush fitting) of your black tank. I don't know your trailer but on many GD trailers the black tank is located in front of the axles and close to the entrance. Look at the middle of my post #3 above for some ideas about tracking that down.

Good luck. Please come back and report what you find.

[Dick Noble]

boyscout -- You are right. I am sure that I did not use that strong a mixture. Also, I washed it off a couple of times with plain water and dried it as well.

[Longshhm]

Thank you all for your input and suggestions. Further usage shows that the smells occur immediately after flushing, but then dissipates within a half hour or so. I can find no evidence of leaking, although, admittedly, I've not dropped the coroplast to look at the insulation. I've been up top and removed the vent cap - no obstruction noted there, but also very little smell coming from the vent pipe. At this point, I'm inclined to think that the vent pipe has broken loose from the tank. Got several calls in to my dealer (who still hasn't any of them 3 days later) and an e-mail sent to Grand Design (still waiting on their response, too). I'll be sure to post whatever I find.

Mike