[amalag]

Actually me and my wife went through approx 1 gallon per day, not 1 gallon per person, so approx 0.5 gal per day per person.

We use an RO filter, provides amazing taste.

[semi-extrinsic]

Friend of mine spent 6 months sailing from Europe to and around the Caribbean and back. He said they planned with 0.8 gallons per person per day. That has some safety margin in it, of course, so 0.5 gal per day per person is likely bang on actual consumption.