Black water tank overflow

It's not uncommon at all for the bathroom sink to drain into the black tank. I know mine does.

What the guy above said. Many bathroom sinks drain to the black tank.

Winnebago has two different plans for the 42qd it has to do with serial number. I picked the first one, check it out it may help

https://www.winnebago.com/Files/Files/Winnebago/Resources/Diagram/2013/13_r42qd_plumb.pdf

As others have said, some rigs do plumb the bathroom sink water into the black water holding tank.

I'm thinking that your rig has a separate holding tank for the 1/2 bathroom sink & toilet, is that correct?

In our rig, all black and gray water go to their respective tanks. If the gray tank overflows, we'll see it in the shower stall. If the black tank fills up...well...you just see it when looking down into the john.

Having a Winnebago product here is definitely an advantage because the technical docs are all online, as posted by craig7h. I really like our rig, but as one who does all of my own maintenance, upkeep and upgrades on the rig, it would be REALLY NICE to have access to all of the documents like Winnebago provides.

~Rick

See my reply on irv2.com

As others have said, some rigs do plumb the bathroom sink water into the black water holding tank.

I'm thinking that your rig has a separate holding tank for the 1/2 bathroom sink & toilet, is that correct?

In our rig, all black and gray water go to their respective tanks. If the gray tank overflows, we'll see it in the shower stall. If the black tank fills up...well...you just see it when looking down into the john.

Having a Winnebago product here is definitely an advantage because the technical docs are all online, as posted by craig7h. I really like our rig, but as one who does all of my own maintenance, upkeep and upgrades on the rig, it would be REALLY NICE to have access to all of the documents like Winnebago provides.

~Rick

I have another question for the OP;
All my life I have been told water seeks it's own level. And I have never seen a bathroom where the top of toilet is higher than bottom of sink. Even if a pipe tied the 2 together how could water flow into sink from toilet?

JRscooby wrote:
I have another question for the OP;
All my life I have been told water seeks it's own level. And I have never seen a bathroom where the top of toilet is higher than bottom of sink. Even if a pipe tied the 2 together how could water flow into sink from toilet?

Can't speak for the OP, but in my case, it's not actually sewage that backs up into the sink.

I have a Tecma toilet (macerator type that pumps to the black tank).

When the tank level gets full and blocks the vent line, the next flush pressurizes the tank - the only way out for the pressure is through drain line from the sink. What actually "backs up" in mine is not black water, just the water from the sink trap. When this happens, it comes with the tank gas and smells just like the black tank.

rdhetrick wrote:

JRscooby wrote:
I have another question for the OP;
All my life I have been told water seeks it's own level. And I have never seen a bathroom where the top of toilet is higher than bottom of sink. Even if a pipe tied the 2 together how could water flow into sink from toilet?

Can't speak for the OP, but in my case, it's not actually sewage that backs up into the sink.

I have a Tecma toilet (macerator type that pumps to the black tank).

When the tank level gets full and blocks the vent line, the next flush pressurizes the tank - the only way out for the pressure is through drain line from the sink. What actually "backs up" in mine is not black water, just the water from the sink trap. When this happens, it comes with the tank gas and smells just like the black tank.

Thank you, the pump idea makes sense. Your explanation got the smell of 4-1 out of my nose.

Winnebago has always plumbed the 1/2 bath sink into the black tank on the 43 and 45 foot Class A rigs along with both toilets. The grey tank gets connected to the rear sink, kitchen sink and shower.