Newfie wrote:Even on boats many, who have desal units, folks report using 20-30 gallons per person per day. They report taking 2 to 4 showers a day, washing the boat every day, washing the anchor chain in fresh water, flushing with fresh water, on and on.
I expect that is just yacht club competition for who has the biggest boat with the most toys and most pampered trophy wife.

In any real situation where you have to haul water or deal with drought restricted supply five gallons a day per person will do and ten would be a luxury.
I remember a drought back in the 1960s where we had to put the old three hole out house back into service. The water used to boil the corn was saved and used to wash the dishes etc.