2008 Keystone Raptor 299MP question

[smitty81503]

Can anyone tell me the order of the holding tank handles on my camper? I bought it used and there are no labels on the three handles. Which is the black water, etc.
:???:

[wingnut60]

Can't tell you which is which, but should be 2 grey water and one black water.
Suggest you get a bucket and open a valve SLOWLY--if nothing comes out, then go in trailer and start running a faucet/shower until you see water at the line. Close and repeat for the other 2. If you happen to get the previous owners black tank contents, close the valve quickly and head to a dump station.