Grey and Black Water Tanks connected?

[randhall]

Hello, I just purchased a 2015 Flying Cloud 28RB. To test the accuracy of the waste tanks monitor I emptied all tanks, then used city water to fill the grey water tank. I ran water in the kitchen and bathroom sinks until the shower drain showed water. I was surprised to find that the black water tank filled approx. 56% (according to the monitor), even though I did not run any water in the toilet. When I emptied the tanks the black water tank was indeed about half full.
Any explanation/ help you can offer is greatly appreciated in advance. Is this suppose to happen? If not, how do I deal with the problem?
Cheers from the Olympic Peninsula, WA

[Wayne&Sam]

The kitchen sink and shower go to the grey tank. The toilet and bathroom sink go to the black tank in our 25'. It's probably the same for you.

[OutdoorIdaho]

The owner's manual has a plumbing diagram showing what drains to each tank.

[ROBERT CROSS]

Old Fart advise...Don't depend on the monitor, it's based on the wild guess principle.

Bob
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[Krikati]

If the drain valves were open, there may be a connection. When you drain the black tank first (as is recommended), then switch to empty the grey tank, water from the grey tank may get pushed into your black tank. Try closing the drain valves and repeat your experiment.

[uncle_bob]

Hi

For whatever reason, AS randomly decides to pipe the bathroom sink into the black or into the gray tank. It's not even 100% clear that the plumbing diagram in this or that manual properly shows this.

Simple answer when sitting at a full hookup site and there's nothing to do:

1) Hook up the hose and dump both tanks.

2) Make *very* sure both gate valves are shut.

3) Pull the hose and run a bit of water. If it comes out, the valve isn't shut ....

4) Put the hose back on now that the valve really is shut.

5) Turn on the bathroom sink and only the bathroom sink. Let it run for a good long time.

Either the black or the gray should climb up past the 40% mark. You are past the "random guess" range by then. Now you know what's what. If both tanks came up to 40% then there is something very wrong in the plumbing .....

Bob

[WHERRWE]

In our 2015 Flying Cloud 28 rear bed, the bathroom sink drains into the black tank.

[JSteff]

You are so lucky! The plumbing diagram in the manual for our 25RB International shows that indeed our bathroom sink drains into black. We think it's quite the advantage, as when one tank or the other is getting full, we can wash hands, or drain dish-washing water into the other tank. We make a habit of washing hands in the bathroom because our black tank fills much slower than gray, most of the time. The 25FB's bathroom sink drains to gray and we've talked to quite a few owners who have to jump through hoops to keep their gray tank from filling too soon.

[NO NOIZE]

Originally Posted by WHERRWE

In our 2015 Flying Cloud 28 rear bed, the bathroom sink drains into the black tank.

Empty tanks, close grey valve, open black valve, turn on bathroom sink, if water comes out the dump pipe, obviously the bath sink is plumbed to the black tank.

[Ray Eklund]

Originally Posted by ROBERT CROSS

Old Fart advise...Don't depend on the monitor, it's based on the wild guess principle.

Bob
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If this trailer was lived in FULL TIME... Flush out the Black Tank. It is full of goodies and harder than Fudge... Flashlight is a good start looking down the 'hatch'. This is a good place to begin.

Our Fresh, Black and Grey Tanks were clean and run clear when we sell. Today our current 27 foot is the same. Good Housekeeping... pays off.

These 'gauges' are estimates... and even then not accurate. Fresh Water. Black Tank. Grey Tank. Drain the Fresh Water tank and get a reading of 20% or more... when empty? That is how they work. They go up fast and down slow, or maybe not at all.

Figure your fresh water tank volume. Estimate your Black Water and Grey Water use. It will total over 150% more, less, somewhat, depends when...

If you want to know if the shower, sinks drain into the black tank. Run water into one sink and have someone watch what comes out of the Black or Grey tank when the valve is open.

It will not kill you. You put whatever is coming out of the Black or Grey Water Tank. You could have a Mound of Feces and Toilet Paper taking up volume. Get a flash light and look down through the stool. If there is... take a hose and let it rip with a nozzle, drain what comes out, dump and repeat. We have no idea why your numbers are off. This is a good place to start with a Black Tank. Many have given advice on why the numbers do not add up and why. You will get if worked out. Get your hands... dirty... sort of.

The Fresh Water will be 100% and then drops. Not one percent at a time, but what appears to be preset numbers.

I do not even trust the Battery Voltage. We look at the number and then open the storage compartment battery voltage to see if the numbers agree. So far those do. I heard even that can be increased or decreased.

Bring along a five gallon bucket. Not refilling fresh water... get a reading on the Black or Grey Tank... and drain into the bucket. Estimate how many gallons. After you do this a few times, you will have a better idea. Although when the tank says 100%... it is time to figure things out. Buckets work. Your reading the gauges is for FUN.

[Gulliver72]

JSteff said exactly what I would have said if I said it first. You’re lucky, and the plumbing diagram is wrong!

[randhall]

Thank you to all that chimed in, great advise. I will isolate and test each sink/ tank next week. Cheers

[Ray Eklund]

Our 2019 27 foot International Signature has the 'normal' grey and black tank distribution as it was the last of the Signature models and no longer going to be made. Using up 'old parts'? For ME... ++++++.

What we heard from the Dealer Sales is that 2019 and future Airstreams will have grey water also flowing into the Black Tank. Maybe from the Shower? While moving it can slosh, dissolve and break down solids. Maybe not the toilet paper, paper towels and whatever else. We add several gallons of fresh water into the Grey and Black Tanks before leaving home. Much like having a cleaning crew working for FREE.

So many owners dump solids, toilet paper with the 3 ounce water flush that they get clogged up and complained, a lot. So... ? This true? Making everyone just happy, happy that they toss more into the Black and forced engineers to add more water and let the 'goods' slosh around? Lucky new owners?

Stationary at a RV Park with the hoses has the Water RUN OUT and leaves Solids to ferment and decompose releasing methane and hardening into an asphalt like organic substance...

Try rolling a tennis ball down the... slinky hose. Afterwards... toss it in the trash. It will be hung up unless your Airstream has a 16 inch LIFT KIT.

Draining your Black Water is nothing close to your Computer Deleting Trash and Junk Emails. Those are FAKE. The Black Water is minimal. What is no removed are the Solids, stranded like Islands, clinging to the bottom of the Ocean, clogging up the system that requires more attention than owners.

Think about it and then comment. I am just the Neanderthal behind the curtain. We figured this out camping in a TENT.

[mattRox]

For what it's worth, our 2018 25FB bathroom sink drains into the GREY tank. Maybe FB vs RB? Trying to find logic here.

[Wazbro]

Originally Posted by mattRox

For what it's worth, our 2018 25FB bathroom sink drains into the GREY tank. Maybe FB vs RB? Trying to find logic here.

Finding logic with decisions from Airstream, that's funny!

[Overstreet]

Wait till the sensor tabs get dirty. ��

[David in Lex]

In our 2020 FC 30 RBQ the lavatory sink (and toilet) drain into the black tank. Kitchen sink is grey. Can’t remember where the shower run off goes; we rarely use the shower.

[uncle_bob]

Originally Posted by David in Lex

In our 2020 FC 30 RBQ the lavatory sink (and toilet) drain into the black tank. Kitchen sink is grey. Can’t remember where the shower run off goes; we rarely use the shower.

Hi

Unless you have a combined black / gray, the shower always goes to the gray tank. The only variable with AS seems to be the bathroom sink.

Bob

[Daytonacoupe]

On our ‘87 the only input to the black tank is the toilet. All other drains enter the grey. The two tanks share a common vent pipe.