waste water holding tank and grey tank 1

We have a compartment labeled waster water holding tank and grey tank 1. Inside the compartment there are two levers. Which one is which? They are not labeled inside the compartment.

If you haven't used the toilet yet (new trailer ?), just pour a bucket of water or two down the toilet. Open the sewer connection and pull one valve at at time. When you get water shooting out, you've found the black tank valve. The other will be for the gray tank. But, there are usually 2 gray tanks and each has it's own valve. Normally, Gray #1 is for the lavatory and shower and Gray #2 is for the kitchen sink.

We used JohnDar's technique and on our 2011 3812 the front valve was the black tank and the second valve was Gray #1. Gray #2 is in its own compartment back by the fueling station. When you do this take some time and patience. We had three people and got slopping water around and at one point were almost convinced that Gray #2 and #1 were reversed due to the time lags. I hope this helps.

Look directly under the trailer with the compartment door open. The lever directly over the larger pipe is the black water valve. On mine it is a little confusing because the larger lever is for the gray water tank and the smaller for the black.