Tank levels

[Dennis66]

Quick question when a tank just lights up full is it really at the top or is there some leeway?

[howson]

Quick question when a tank just lights up full is it really at the top or is there some leeway?

If it's the black tank, you'll hear a "burp" when flushing if it's close to full. (I've never personally heard this "burp" as the tank is flushed every two or three days regardless of what the level indicator shows.)

For the gray tank(s)--if the lights are truly reflecting reality (doubtful!) the tank is very close to full. You'll know for sure the tank is full when water backs up in the shower or whichever sink you're using.

[Jlawles2]

Dennis66 You may want to use the water meter and measure how much water is in the tank when the light just comes on. I seriously doubt based on MH experience (1982 model), 2014 TT, and , 2019 5er prior to this one that the tank is 100% take no more full. If it were, by the time the indicator came on and someone checked it, there would be a waste water spill inside the camper.

[ThePowells]

I'll second howson. Both tanks are below the floor level of the pass thru. The toilet has 30 inches +/- a bit of 3 inch line going to the tank. When water starts backing up into that line, you will then start getting the burping. At that point, your black tank will be about 105% full. If you have one gray tank, the first back up will be in the kitchen sink. If your galley has it's own gray tank, then the backup will be into the shower and you will be probably 110% full. When we are out at FHU, I purposely fill the gray tank to the point that water accumulates into the shower or the bathroom sink runs slow, and then drain the black, then close the output valve, use gray water to backfill the black tank for about 10 seconds, and then close the gray and open the output valve and drain black and then gray. The water turbulence does a great job at removing stuff from the black tank. I did install a high water alarm in the vent stack for the black tank simply as a back up to the lights and losing track of tank flush filling.
I'll check my lights when I get home and see what I have since the black tank got a thorough cleaning Sunday. If you use a washing machine, that makes it much more likely that the gray tank will read as full when it isn't. The soap and detergent seems to want to coat the walls and there is very little airflow to dry the tank out enough to where the sensors don't have a moisture supported contact path.