I have a VacuFlush head
on my boat, and I think Gord's referenced link is pretty accurate on the volumes. It uses a lot
per flush. You might want to consider installing one. The ladies, in particular, will appreciate the convenience of not having to pump a manual head
. In fact, my wife made it a condition of buying
our boat that the brand new manual head had to go, in favor of a new VacuFlush. Note, however, that the VacuFlush uses fresh water, not seawater. That, by the way, means you won't have the typical stinky head that comes with using seawater.
I'd like to make another point that some may consider sexist on the surface. The number of flushes will go up in proportion to the number of females on board. I've sailed with all male crews of four and a two-couple crews of four. For apparently valid biological and/or anatomical reasons, males require less water for flushing
. When my wife is onboard, the two of us use 10-12 gallons of fresh water per day, for all
purposes, including her daily shower
and my off-the-stern wash-down. If it's just me, water consumption
goes down to about 3 gallons per day or less.