Dual sewage drains?

[CooterB]

I'm very new to RVing and this is our first 5er. We bought used from a dealer and they gave us a quick run-through, but we didn't know what we didn't know. So, I have a lot of questions. Thanks to so much information on this forum, I have been able to answer most of them.

There are two sewage drains. One is obviously the "regular" one, as the pipe is 3ish inches in diameter. The other is much smaller; on the order of 1.5" prior to the capped connection point. When we hooked up at our first park, I did not connect anything to the smaller point, but since have realized that something is draining through it and have a sewage hose connected and draining it.

Can someone please explain the dual sewage drains? Is the black tank and one of the grey tanks on the large one and the other grey tank on the smaller one? Also, there is a distinct odor in the kitchen, but that may have been solved by me opening and leaving open the drain valve on the second grey tank. I have completely drained and flushed the black tank, and BTW the monitor says it is 2/3 full. TIA.

[Mikendebbie]

Mike - can you post a pic of the two connections. This is a new one for me - but maybe others have heard of it and will know what the small connection is for.

[rohrmann]

Many times when they can't get the plumbing tied together because of obstructions, they will have two outlets, so yes, probably the black and grey tanks are on the 3 inch and the galley is on the two inch. You can use a Y fitting and a short length of hose so you can have both drains connected. https://www.campingworld.com/rhinofl...alves-fittings

[jsb5717]

I agree with the "Y" fitting, had to do that on our previous 5er with 2 sewer connects. However, a smaller exterior drain is a new one for me. I am aware of only the one type of sewer connection used for draining tanks. Is there some new trick for this old dog to learn? Yes, a pic would be helpful. It's possible that a previous owner changed something.

[Carl n Susan]

Originally Posted by Mikendebbie

Mike - can you post a pic of the two connections. This is a new one for me - but maybe others have heard of it and will know what the small connection is for.

This is a new one to me too. I have seen a second outlet, usually for a second black tank, but it is always a 3" outlet.

[Mikendebbie]

If I had a photo so I could see how the two sit in relation to each other - it’s the sort of thing that would drive me nuts until I re- plumbed them together into a single hose connection. I’m just too lazy to want to mess with two different size hoses every time we set up...but that’s easy for me to say sitting in this easy chair typing this comment and not knowing how difficult a re-plumb would be for you.

[CooterB]

Well, I see that I have confused the crowd. Both of the sewage drains are 3" connections. It's just that one of those 3" connections is on the end of a 1.5" pipe. As soon as it quits raining, I will post a pic of the connections.

[CooterB]

Here is the pic

[jsb5717]

That's not an unusual setup. I had this on my last 5er. Only one black tank but I assumed that the tanks were far enough from each other that they added a separate outlet.

[Mikendebbie]

Thanks for the pic Mike. Now it makes sense.

[RMcNeal]

I've seen several Toy Haulers that have a second bathroom, 1/2 bath sink and toilet only, that have 2 outlets like this. I've never seen a connection that isn't 3" though. Most people I have seen with 2 outlets generally use the "Y" connector to bring them into a single hose to the sewer connection.

[CooterB]

Robert, the two hoses go into a wye right at the hole in the ground. I have a clear wye there. It just made more sense to do it that way, at this CG.

All, it seems to be working, but I still am unsure about what is draining from the second sewage outlet. I assume it is coming from the kitchen sink, but am unsure.

[RMcNeal]

If you don't have a second bathroom in the rear of the coach, then it is most likely the kitchen grey water. To confirm, you could open the drain valve on this line, turn on the water in the kitchen sink and go outside to see if it is running through the drain.
I have 2 grey tanks and 1 black tank, but only 1 outlet under the rig. If you have the 373RD (rear den), then your kitchen is in the middle like mine. I wonder why they didn't plumb the 2nd grey tank to the same outlet?

[jsb5717]

In my last 5er the 2nd sewer drain was just the kitchen galley water.

[JandC]

Is it set up for a w/d? Where does the washer drain?

[DutchmenSport]

My current Montana fifth wheel:



This is the reason I always carry a LOT of hose. I have 4 more sections, for a total of 10 lengths, and yes, there have been times I've had to use it all.

Here's our previous travel trailer, a Keystone Outback:



Another good reason to carry lots of length:

[CooterB]

It is, but we don't have it installed. I think it is from the kitchen sink.

[CooterB]

J&S, I believe that is what it is. I have tested it and it seems to be.

[MARK A]

Looks like possibly a previous owner add on to prevent filling the tank in a long term hook up situation.



Mark

[CooterB]

Thanks everyone. I believe the second drain is from the grey tank that holds kitchen drainage. Everything seems to be working as expected.