holding tank plumbing question

[phenrichs]

I have a 2012 Sprinter 311BHS. It has 3 tanks. 2 grey and 1 black. I am trying to figure out what is draining where.

I want to know exactly which water sources end up in which tank. I am most curious to know what besides the toilet drains to the black tank.
I have suspicions that my bathroom sink drains to the black and perhaps the shower. Our first trip out the black seemed to fill way to fast for a weekend. We didn't use the shower just the toilet and sink. Although part of it may be a teaching issue with our small children and flushing.

[gkainz]

No idea but a quick way to check would be to make sure all tanks are empty, close all the dump valves and run a gallon or so of water down each drain, one at a time, and open the dump valves between each gallon. That will tell what dumps into what.

[skifreak76]

i have the same trailer and same year. it was described to me that the larger gray water tank is for the bathroom sink and shower, and the outside kitchen sink. the galley tank is the smaller tank that is just for the kitchen sink. and the black water tank is just for the toilet. hope this helps, Ken

[phenrichs]

I wonder if something just got stuck on the sensor that made the black tank appear full. Seemed odd that it was 2/3 full after only a weekend. I do think a little teaching for the kids on flushing the rv toilet is in order.

[rnkburg]

What type of chemical did you use, heard if you don't pit enough water in the bowl when flushing the powder chemical it will cause the sensors to mess up

[johnnyrose]

Phenrichs,

Skifreak is correct on this one. Most, if not all trailers with two gray tanks have a galley tank just for the kitchen sink, a gray tank for all other waste water other than the toilet and the black tank is strictly for the toilet. That being said, the black tank sensor is often tripped by solid waste sticking to it and skewing the reading on that sensor (mine does it all the time). You can agitate the tank after emptying it with a couple of gallons of clean water to get that stuff out of there or use one of the after market sprayers that are sold through camping stores such as Camping World. Hope that helps!

[fla-gypsy]

A little liquid laundry soap and liquid fabriic softener will help the sensors stay clear but they are notoriously inaccurate under perfect conditions.

[phenrichs]

Mine has a factory built in black tank flush. Just hook up the hose outside and open the valve. I will admit that it was the first time we had taken it out so there was nothing in the tank when we started other than a few gallons I put in while setting up camp.

[JRTJH]

Some outdoor kitchen sinks drain into the black tank. If this is the situation with your RV and you used that sink during the camping trip, it may well have nearly filled your black tank. There was a big discussion on another thread in this forum about the "drain hose/valve" on the outside sink not having a P trap on it and black effluent (probably just the gas) flowing back to that sink and causing the outdoor kitchen to have undesirable odors. You might want to verify where your outdoor sink drains. There may be nothing wrong with your black tank sensors.....

[DEW]

My Laredo has an outdoor sink and it does drain into the black tank. I know this for sure as I performed the test indicated earlier about pouring a a few litres (sorry the Canadian in me slipped up) I mean a gallon of water down each drain to see where it emptied.

There is no P trap on this out door sink, but you can see there is something in line with the drain on my Laredo - so I assume it is a 1-way check valve. I have never smelled sewer odor in my sink drain.

Maybe yours is the same way... hope this helps.

[Kb86]

I have a 2012 Sprinter 311BHS. It has 3 tanks. 2 grey and 1 black. I am trying to figure out what is draining where.

I want to know exactly which water sources end up in which tank. I am most curious to know what besides the toilet drains to the black tank.
I have suspicions that my bathroom sink drains to the black and perhaps the shower. Our first trip out the black seemed to fill way to fast for a weekend. We didn't use the shower just the toilet and sink. Although part of it may be a teaching issue with our small children and flushing.
We have 2013 311BHS and last year noticed foul smell every time we opened the hatch to the outside kitchen. We have 3 kids under 7 and they use the outside sink and often leave the water running while washing hands etc. last time we camped the black tank was getting full and didn't realize how full until brown 'water' started filling the bowl in the outdoor kitchen sink.
Fully emptied the gray tanks. Fully. Sink was still full. Pulled the black tank....sink emptied. Not comforting knowing we wash dishes in that sink, store food in the cabinets and our oldest sleeps in the bunk above the cabinets with a continuous smell coming up through the sink!

[JRTJH]

There is a thread here that's about 2 years old regarding exactly what you're experiencing. It seems a P trap won't work on a moving RV, so the manufacturers came up with a "one way valve contraption" (I'm trying to be nice) to drain the outside sink into the black tank. You're not the first one to have that valve fail and black tank effluent perk up into the sink. If you're still under warranty, take it to the dealer and have them fix it right, if you're out of warranty and need to do it yourself, you can "try" the replacement valve route, but what some have done is remove the drain from the black tank, seal the tank so it won't leak or smell and then build a new drain for the sink that goes into a blue tank or into a 5 gallon bucket.

Do a search for outdoor sink drain, or outdoor sink and you should get a lot of good information.

I can imagine how you felt with "brown dishwater" YECHT :(