Connecting front and rear gray tanks

[TomPanning]

On our Reflection 28BH fifth-wheel, there's one black tank and two gray tanks. The front gray tank is for the bathroom and is right next to the black tank. Both of those tanks drain out of the front sewer connection. The second gray tank is behind the axles and is just for the kitchen sink. It drains out of a separate sewer connection behind the axles.

It would be nice to connect the two gray tanks somehow, for two reasons:

1. When we have full hookups, I could make just one connection to the trailer. Right now, I have to run two sewer hoses (and usually at least one of them requires an extension) to a Y connection.
2. When we're at a campsite without sewer hookups, I could use a gate valve on the output to "tie" the two gray tanks together. Right now, the shower gray tank will fill much faster than the kitchen tank.

I've had the chloroplast down already for other reasons, and unfortunately the fresh tank is over the axles between the front and rear gray tanks. There's a little space on either side against the frame, but the side that has the sewer connections is also where the hot and cold lines run to the rear, along with the underbelly furnace duct, so adding a rigid pipe there seems complicated at a minimum. To make things even more complicated, the two sewer outputs (which are pretty much in line with the actual tanks) are about 15 feet apart, so in a house you'd want almost a 4" drop in the pipe over that distance.

Has anyone tried to do something similar in their trailer? What did they do, and how has it held up over time?

(I'm sure people talked about this before, but I can't seem to find the right search terms to find the forum posts. Feel free to just point me to the right forum posts or search terms if there's already a good discussion somewhere.)

 

[huntr70]

On our Reflection 28BH fifth-wheel, there's one black tank and two gray tanks. The front gray tank is for the bathroom and is right next to the black tank. Both of those tanks drain out of the front sewer connection. The second gray tank is behind the axles and is just for the kitchen sink. It drains out of a separate sewer connection behind the axles.

It would be nice to connect the two gray tanks somehow, for two reasons:

1. When we have full hookups, I could make just one connection to the trailer. Right now, I have to run two sewer hoses (and usually at least one of them requires an extension) to a Y connection.
2. When we're at a campsite without sewer hookups, I could use a gate valve on the output to "tie" the two gray tanks together. Right now, the shower gray tank will fill much faster than the kitchen tank.

I've had the chloroplast down already for other reasons, and unfortunately the fresh tank is over the axles between the front and rear gray tanks. There's a little space on either side against the frame, but the side that has the sewer connections is also where the hot and cold lines run to the rear, along with the underbelly furnace duct, so adding a rigid pipe there seems complicated at a minimum. To make things even more complicated, the two sewer outputs (which are pretty much in line with the actual tanks) are about 15 feet apart, so in a house you'd want almost a 4" drop in the pipe over that distance.

Has anyone tried to do something similar in their trailer? What did they do, and how has it held up over time?

(I'm sure people talked about this before, but I can't seem to find the right search terms to find the forum posts. Feel free to just point me to the right forum posts or search terms if there's already a good discussion somewhere.)

Not enough space for the needed drop to get them together, that's why they are plumbed the way they are.

 

[TomPanning]

I found someone who has done this on the same floor plan, and posted a video explaining how. He even mentions that he has the required ¼” drop per horizontal foot.

Having lived with two drains for a while, this is definitely a mod that I want to complete.

The only disadvantage I’ve heard so far is: if I’m at a dump station that is out-of-level I might not be able to fully drain the tank. In that scenario, I would have to put my rear levelers down to fully drain the tank. I can live with that.