Windsor pump out

[TrueBlue]

Boats properly designed for inland waterways use always use freshwater from its tankage.

The amount of water used in a dump through system is small - a pint or so.
Posher, more modern, nicer systems using a vacuum system use about twice as much.

Folks who have vroom vroom seagoing kit have different parameters so need to cut down on what fresh water they carry.

 

[boatone]

Boats properly designed for inland waterways use always use freshwater from its tankage.

No doubt that's why they spend so much time filling up at watering holes

And I think you need to think about the "dump through" comment - I believe there are some NB systems which are pretty much a straight drop but most cruiser sea toilets are pump thru - whether to holding tank or sea - and I can assure you they use somewhat more than a pint of flush water !