Tank Capacity Accuracy?

[chops1sc]

I am curious if anyone has ever done a test with their tanks to see what the actual capacity is at certain lights. If my tanks are 39 gal, is the 1/3 light actually 13 gal? 2/3 actually 26 gal? I think I'm going to measure each tank and see.

I am asking this because on our first trip with the new camper we had to go dump on the 3rd day because the grey water was full (not draining full ). I purchased a 28 gal external dump tank and if I get to 2/3 full I would like to think I could put 26 gal of grey water in there (or black).

I know these factory panels aren't the greatest and over time the sensors will get dirty and possibly not work correctly. I figure a new camper with "clean" tanks is the best place to start!

[JFlightRisk]

The "full" sensors are usually a bit down from the tops of the tanks so there's some additional room before the tanks are actually full. Sensors will be spaced "sort of" equally apart on one side to give an idea of how full or empty they are. Definitely not as exacting as say a fuel gauge in a vehicle.

[bankr63]

Too late now for you, but I just bought a dump tote that was a couple of gallons bigger than my biggest tank. That way I know I won't overflow it.

Even if you do get it 'figured out' with clean probes, you will never really know once they are dirty. My black shows full even with the tank completely empty now. I just go by the toilet burping. If it starts I know I have to dump very soon.

[Kevin Cooper]

Most people’s sensors do not work at all correctly. I wouldn’t make that my standard for doing anything. I use Borax, so my sensors work.

[CAG]

Originally Posted by chops1sc

I am curious if anyone has ever done a test with their tanks to see what the actual capacity is at certain lights. If my tanks are 39 gal, is the 1/3 light actually 13 gal? 2/3 actually 26 gal? I think I'm going to measure each tank and see.

I am asking this because on our first trip with the new camper we had to go dump on the 3rd day because the grey water was full (not draining full ). I purchased a 28 gal external dump tank and if I get to 2/3 full I would like to think I could put 26 gal of grey water in there (or black).

I know these factory panels aren't the greatest and over time the sensors will get dirty and possibly not work correctly. I figure a new camper with "clean" tanks is the best place to start!

Tank Capacity Accuracy is an Oxymoron and don't worry about it. Any effort to correct or explain it is a waste (pun intended) of time.

[ARoamer]

I was mainly concerned about how much fresh water I was carrying. I don't want to travel with a full 75 gallon tank, but we need enough to do a night or 2 of dry camping when traveling. I used used a water meter and got 30 gallons in before 1/3 showed on the RV panel. Also, keep in mind most tanks are maybe 6-8" tall and 36-48" wide, and the sensors are mounted on one side, so not being level can make tank sensors even more inaccurate by a lots of gallons.

[CAG]

Originally Posted by ARoamer

I was mainly concerned about how much fresh water I was carrying. I don't want to travel with a full 75 gallon tank, but we need enough to do a night or 2 of dry camping when traveling. I used used a water meter and got 30 gallons in before 1/3 showed on the RV panel. Also, keep in mind most tanks are maybe 6-8" tall and 36-48" wide, and the sensors are mounted on one side, so not being level can make tank sensors even more inaccurate by a lots of gallons.

Rather than guess I always us a meter attached to the hose.