Black tank flush 2021 T@B 400 question

Polanskyster

Today I did a Black tank flush.  I connected the water hose to the black tank flush nozzle on the brand new Nautilus panel.  I opened the black tank valve. Connected the sewer hose.  Turned on the non potable water from my storage facility.   

Here is my question and problem:  why did the the water fill my fresh water tank and also flush the black tank through the sewer hose?  Should I be concerned black tank matter going into my fresh water tank?  Any ideas?

ChrisFix

@Polanskyster
I have the same model 400 as you, and the black tank rinse should definitely NOT be filling your fresh water tank.
There is a Nautilus valve configuration to "Power Fill" the fresh water tank from the white (left side) "city water" connection...but the black tank rinse and the fresh water are never intended to come together.
Are you certain that the fresh water tank was filled during the black tank rinse?
If you had a steady supply of water coming from your black tank drain while using the black tank rinse, it would indicate that it was correctly adding water to the black tank, not the fresh water tank.

Polanskyster

Thanks ChrisFix for your response.  The hose was in the Black hose input of the Nautilus.  My Fresh water tank was empty prior to the Black tank rinse.  After the rinse I drained the fresh water tank for several. minutes.  I’m certain the fresh tank was filled during the rinse, I heard it being filled.  It was really strange.

There is no Nautilus configuration for rinsing the black tank.  The dry camping mode was used during this rinse.  The time I rinsed prior to this time I used the City water mode and  there was no problem.

Sharon_is_SAM

Can someone get a good picture of the 400 Nautilus from the rear so we can see the plumbing connections.  @Polanskyster, you can follow the plumbing line off the tank flush at the back of the Nautilus to see where the water goes.

ChrisFix

@Polanskyster
The fresh tank drains slowly, and there is almost always some more you can drain by tilting the trailer in different directions.
The sound you hear with the black tank flush is probably the black tank filling...It makes a similar noise to power filling the fresh tank.
Unless you had gallons of new fresh water, I don't think it is being filled from the black flush.

Polanskyster

@ChrisFix your comment makes lots of sense. I certainly hope so.  I will follow up in a few weeks on my journey to Utah.  Thank you

Denny16

As far as your black tank rinse goes, the black water hose fitting should go to the black tank directly and there is a check valve at the black tank end to prevent water coming back up.  This is dedicated water line on all the other TaBs that have this feature.  Chris is spot on concerning your water tank.  

Have fun on your next trip.
cheers

Kampa2020

Should we be using a water pressure regulator for flushing the black tank as well?

Denny16

That would be a good idea, it would not hurt if the source water pressure is higher than 50psi.  You can put the regulator between the outside faucet and hose, if using a RV park,hookup.  At a dump station, just use the wash setup provided.
cheers

ChrisFix

Kampa2020 said:

Should we be using a water pressure regulator for flushing the black tank as well?

I would just to be safe. Ideally, it isn't needed, as the black tank flush only goes to the open flushing spray inside the tank, so it can't build any pressure in the lines...but I use a regulator on my black tank flush hose as a 'just in case' prevention (like if the black tank flush spray was to clog entirely).