The level indicator has never worked reliably since we've had our 07 Niagara. Had installed a level gauge on fresh and gray water tanks last fall and had one unused guage so decided to replace the OEM probe. Guage I have uses three probes that are supposed to be installed through holes drilled in tank wall, but I didn't want to do that and have wires exposed inside the PUP. Instead installed them in a ten inch length of PVC pipe that fit through the rubber grammet where the OEM probe was installed. The guage only needs two wires back to the indicator panel, so used zip cord out the top of the PVC probe I'd made, passed it through the wall of the bathroom, then down the other side of the wall to a hole through the floor, and then to the indicator panel. Now I have level indications at 1/3, 2/3 and full for the black water tank instead of the 3/4 and full provided by the ORM probe. Email me if you want more details - making the PVC probe took some work! Sorry, I don't have pictures.
2006 Explorer EB V6 w/TP WDH (Picture is wishful)
2007 Fleetwood Niagara
My 06 Niagara does not have greywater holding tank, so if not hooked up to the big blue tote, I'm on a sewer site. And, if not hooked up to either, and I am dumb enough to drain too much water via the sink, then I get my feet wet when I step into the shower pan!
As to the blackwater holding tank - it's easy to determine how full it is by looking when flushing!
For what it is worth, the level indicator in the 08 Niagara is no better. It is very inconsistent. I have thought about replacing it since we bought the camper. I also want to add level indicators to the grey water tank. Do you have a brand that is more accurate??