I'm still getting use out of this water meter. It's very handy to have.
The latest use was for checking the grey tank and black tank capacity and also checking how the indicator lights on the monitor panel compare to fluid levels in the tanks.
This testing was on my older Triple E Class A motorhome. The brochure didn't split the grey and black tanks individual capacities and instead just listed a 78 gallon holding tank capacity.
I particularly wanted to test the capacity of the grey waste tank because, based on the monitor panel indicator lights, it would get full faster than I expected.
The testing showed that the grey tank capacity is 40 gallons and the black tank is 38 gallons.
The monitor panel light indicator system is calibrated nicely for the black tank with the 1/2 full light coming on at 20 gallons and Full coming on at 34 gallons - only 4 gallons less than actual full capacity but still an adequate and useful margin. I won't adjust that calibration.
The monitor panel light indicator system for the grey tank was not calibrated accurately for the grey tank with the 3/4 light coming on at 14 gallons and full coming on at 21 gallons with 19 gallons worth of space remaining to actual full capacity. I've adjusted that calibration now so that the Full indicator light comes on at 38 gallons - only two gallons from actual full capacity. I might further tweak that setting such as maybe having the Full light come on with say still leaving enough space in the tank for one or two more showers. I'll use it and think about for a bit.
Here's a video I found on Youtube showing how to calibrate the monitor panel light indicator system: