Info on class C rv

[Cathy and Paula]

I am trying to figure my friends rv out and I am a little confused. They have 2 gray levers and 2 black levers for their holding tanks. They have 2 gray levers and 1 black lever on the drivers side and the other black lever is on the other side and the holding tank. Could someone explain why they have this configuration. This is a first for me.

Thanks

[Kirk W]

That isn't much to go on. Can you post some pictures? 

[Yarome]

Rare, but it happens, especially in smaller rigs in an effort to maximize overall tank capacity as well as helping to balance the rig. I'm going to guess the 2 gray's on the driver side are somewhat back and forward from each other or one will be set at an angle and the other more perpendicular to the curb. That's likely the bathroom sink tank and the shower tank ("clean" gray water). The more forward valve being the dump valve and the other combining the two smaller tanks. The black lever on the same side would be the black tank (we know because the grays are needed to flush the black).

The black on the opposite side is likely the kitchen sink "black" tank ("dirty" gray water).

A lot of folks just leave the tank combiner valve open when parked. That allows the bath sink and shower to equalize across both tanks and close it while on the road. 

Seeing that Class C tanks can be rather shallow and long... it also helps purge the tanks when the volume weight is more contained in smaller tanks rather than in one "very" long and shallow one.

But... I could be wrong. 

On Edit: With the year, make & model it would be possible to confirm that for you.