If my battery is charged from the alternator, I don't have problems with the water going down. If I plug my RV in and the power supply charges the battery, it will cause the water to go down.
I left my RV plugged in for a long time but forgot about the battery. It almost made the battery go dry. Since the acid was almost all gone, adding water wouldn't do anything. Since I had no place I could get sulfuric acid to replenish what was lost, the battery was scrapped.