Bathroom sink drains to the black tank? That was a surprise!

[steverino]

Originally Posted by andyherman

I put a deposit on a 2018 27FB and it appears the bathroom sink drains into the black tank on that model (my 2007 Safari 27FB bathroom sink drains into the gray water tank). I was considering a 30 but after watching the Wandering Wagner's and their comment about their bathroom sink draining into the black water tank, I nixed that idea. It's absurd to me that they would drain the bathroom sink into the black water tank and not the gray water tank.

There appears to be sufficient confusion on this topic, especially if there are reports that newer 27FB’s are plumbed differently than older ones. Definitely my 2010 27FB lav drained to gray. Then again, Martee reports a 2018 25FB (with a virtually identical bed/bath floorplan as the 27FB) has a lav draining to gray.

Reading a couple threads on this topic, I am beginning to see a possible pattern... FB lavs draining to gray, RB lavs draining to black. But I won’t take bets on where my 30 RB drains until I test it :-)

Perhaps a call to Jackson Center customer support is warranted in your case to get the straight scoop.

[OTRA15]

You can't rely on any AS owner's manuals or schematics as gospel about where your particular bath sink drains.

Only the full-scale-model testing reported here will work definitively.

With an empty grey tank, and its drain valve open, pour water down the bath sink drain. If water comes out the grey drain, you have your answer. If not -- with the trailer very quiet, and no water pressure, hold the toilet flush stopper open, and pour water down the bath sink drain. You should hear it falling into the black tank [which should be empty-ish]. This must be done without running the pump because it is too noisy.

You can probably trust that the plumbing will not change configuration after this test, thus it need be done only once in the lifetime of your trailer.



PS -- If you can't perform the test above, these search results show other threads/posts on "sink drains into black tank" --

https://www.google.com/search?q=sink...=airforums.com

[andyherman]

Unfortunately, calling Jackson Center is not always a good option.
I called them because I wanted to replace the cloth covered flip down doors on my 2007 27FB with new doors that have the laminate. I also wanted to replace the white laminate Galley counter with a factory one that has the newer faux Corian finish. I got the part #'s from JC and gave them to my dealer. He sent me an e-mail a week later and JC quoted $2,345.68 for just the Corian Galley counter so I opted for the laminate instead, which was @ $400.00. I told the dealer to go ahead and order all the parts - 2 flip down doors in the lounge, the anchored panel where the furnace cold air return is located and the laminate galley counter.
When I went to pick up the parts, the dealer brought out the galley counter, which was what I wanted and 3 other "packages", 2 of which were really big and looked like they couldn't possibly be the flip down doors I wanted (the 3rd package with the anchored panel for the cold air return was fine). I told the dealer the two other huge packages couldn't possibly be the right parts. When we opened them up, neither of us had a clue as to what they were or where they went in any Airstream - they definitely weren't the flip down panels for my 27FB. We walked out on the lot and I showed him the flip down panels on one of the new FC 27FB's I wanted - they are all exactly the same size and shape as my 2007 27FB.

The dealer called JC and spent @ 45 minutes on the phone with them but JC couldn't even tell him what the parts (part numbers) they sent were for. I left with the 2 correct parts and a couple of weeks later the dealer e-mailed me with what were supposed to be the correct part #'s. He asked me to take photo's of the pieces I wanted and provide the exact dimensions, which I did. It took @ a month and half until JC shipped the "new" parts.
So JC isn't necessarily the definitive source for accurate information. They also "prefer" that you go through the dealer with these types of questions. I did call Colonial Airstream to ask how the International Signature 30 bathroom sink was plumbed as I was thinking of going with a larger model. The first guy I spoke to didn't have a clue and asked another Airstream salesman who said the Signature 30 bathroom sink drains into the black tank. (I didn't think to ask him about the Signature 27FB as I "assumed" it drained the same way my Safari 27FB does - into the gray water tank.)

[A W Warn]

IMO, the lavatory sink draining into the black tank is a good thing.

My reasoning;
1. When boondocking gray tank is always the first to be filled. The black tank never fills completely.
2. Additional liquid from the sink would increase tendency to flow freely, helping flush solids from the black tank.

My Safari that has an above floor black tank that does not have a tank flush/wash system. So, I have to go into the bathroom to fill the bowl a couple times to rinse/flush after draining the black tank.

Since the black tank vent is adjacent to the lavatory sink in my trailer, I am considering changing the plumbing so that the lavatory sink drains into the black tank.

[VaTravelers]

My 2017 28’ Serenity International lava sink drains into the black tank. I have learned to make sure there is water in the trap (especially after towing) to prevent black tank odors from escaping into the trailer. The toilet has a rubber seal and we normally keep about a cup of water in the bowl to prevent odors from escaping.

[RichardW]

The bathroom sink in my 2015 27FB International Serenity drains into the grey tank. I checked this by draining the grey tank and watched it refill from the bathroom sink tap. It's not obvious why some models drain into the grey and others to the black.