Well... OK then.
I always fill it, from home, I use an adapter and fill the passenger side direct to the tank fill and wait for bubbles out the vent.
On the road, while I am hooked up, I turn the 4 way valve to fill and go around and open the passenger side fill and wait for the water.
I do use the fresh water tank for cooking, drinking, showers and flushing. I just wait till the sensors say I only about a 3rd left and refill next chance.
But I will keep that meter in mind, it's certainly inexpensive.
Don