How big is my holding tank?

[jeepbluetj]

Originally Posted by basssears

So forgive my ignorance as I'm new to the holding tank thing, start filling it until "what"... ie what am I waiting for to happen so I know it's full... does something nasty start oozing out of the deck pumpout fitting, or how do I know it's full (no gauge or light on it)?

-- Bass

Something nasty will come out the vent if it's lower than the pumpout. The pumpout if the vent is higher and the pumpout is open.

I'd use some basic geometry and math.

If the tank shape is so irregular, you can fill it from the pumpout (with water) and see the level rise.

But so what? Let say you figure out that you have a 40 liter tank. (~10.5 US gallons, 8.8 imperial gallons, something like 1.2 US bushels) But now what? Do you know the volume used every time you/guests take a leak? Flush? Etc? Sure it's nice to be able to tell folks you have a 4.54 peck holding tank, but it doesn't tell you when it's gonna be full. But if you know that you pee a cup each time, and use 2 cups of flush water that 40 liter tank will be full in 55 pees. I propose a new unit of volume named a "Pee" that's equal to 3 cups.

Either:
1. Live with it for awhile, you'll figure it out.
2. Put in a gauge.

(units chosen to maximize humor value. Sorry, couldn't help it)

[boatpoker]

I'd be more concerned about what uric acid has done to those cheap domestic gate valves than the size of my tank.

[Xthewater]

Originally Posted by jeepbluetj

Something nasty will come out the vent if it's lower than the pumpout. The pumpout if the vent is higher and the pumpout is open.

I'd use some basic geometry and math.

If the tank shape is so irregular, you can fill it from the pumpout (with water) and see the level rise.

But so what? Let say you figure out that you have a 40 liter tank. (~10.5 US gallons, 8.8 imperial gallons, something like 1.2 US bushels) But now what? Do you know the volume used every time you/guests take a leak? Flush? Etc? Sure it's nice to be able to tell folks you have a 4.54 peck holding tank, but it doesn't tell you when it's gonna be full. But if you know that you pee a cup each time, and use 2 cups of flush water that 40 liter tank will be full in 55 pees. I propose a new unit of volume named a "Pee" that's equal to 3 cups.

Either:
1. Live with it for awhile, you'll figure it out.
2. Put in a gauge.

(units chosen to maximize humor value. Sorry, couldn't help it)

Almost peed myself reading this! Might need a poop volume component in the calculations, perhaps an average calculated as a ratio. Which would make this a unit of volume named a "poopee?"

[seasick]

I second boatpoker's observation. Those gate valves were my first concern. Volume of tank in gallons is less important than number of average head uses per pump out.