What size waste tank to buy?

wa8yxm wrote:
36 gallon. the 1st size up from your waste tanks.
That way you won't ever overflow the tote .

This^^
How will you put 32 gallons of water in a 21 gallon tank?
How will you know when to stop filling before the 21 gallon tote overflows with 32 gallons of water?
Can you say?, "Oops there is a grey water mess"!
Avoid the hassle of overflowing your tote and get a tote big enough to take the full capacity of your grey tank.

Unless they have worked in utility operations, everybody seems to underestimate the weight of water (any color).

A pint's a pound, the world around. ;)

Not quite accurate since a gallon of water weighs a little more than 8 pounds.

Since we only use our tote tank for gray water and there's only two of us, we went with the 15 gallon tank. Any bigger gets harder to deal with it.
We're able to go at least 2 weeks without dumping our black tank.