As said earlier, level indicators are not always accurate, depends on who stuck the sensor in the side of the tank. We have a 47 gallon Black and total of 87 grey. we have made a full 9 days, 2 adults and an additional 3 grand kids for the last three days. black sensor, like always shows 1/3 after the first day, 2/3 after about day 3 and full by day 4 or 5. So when we got home for the longer trip, i took a five gallon bucket, and added it to the black. I was able to add about 12 more gallons before I could see the water in the pipe below the floor. I know i can do a whole 10 to 14 days before i need to flush. We did the same with the grey and was surprised how much capacity is really left after sensors read full.
