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→Calculating Water Capacity
For a standard office, guidelines are 25 gal/day per person but have been shown to be as low as 6.8 with conservation measures <ref>http://ncprojectgreen.com/</ref>. Of course, office estimates don’t include cooking, showering and washing clothes, etc.
For domestic consumption, [http://www.watertechonline.com/ WaterTech.Online] also recommends 25 gal/day d per person but [http://www.nrcan.gc.ca/ Natural Resources Canada] (NRCan) estimates real usage as 88 gal/dayd.
NRCan says average daily consumption is 1000 Ll/day d (264 galsgal) for three people with 40% for toilets. This puts Canadians among the thirstiest on the planet. Must be all the Beer! More Beer! My toilet flushes with 1.6 gal so NRCan assumes I hit it 22 times a day, or about every 45 min. Putting aside the toilet jibe, I find 88 gal realistic, as shown later.
[http://www.ec.gc.ca/eau-water/ Environment Canada] estimates daily per capita usage as 79 gals. <ref>https://www.ec.gc.ca/indicateurs-indicators/default.asp?lang=en&n=7E808512-1</ref>
Vendor specifications also indicate that many marine toilets require 3-5 gal per flush, with the most efficient (VacuFlush) requiring only 0.10 gal./0.39 liter.<ref>http://www.dometic.com/USA/MS-11346-Marine/PG-11395-Toilet-Systems#q2</ref> The more profligate ones can use seawater but VacuFlush requires fresh water.
Other sources estimate that domestic hot-water consumption alone runs 20-35 gal/day per person, with a peak demand of 10 gal. To meet such a peak demand, the [[HotWaterHeater|hot water heater]] must deliver 10 gal/person at any time. Additional capacity is needed for appliances, such as dishwashers.
== Conclusion ==
Before doing the above test, I had settled on 25 gal/person/day as a design goal. Afterwards, and because water capacity is so critical for a live-aboard, I increased this to 60 gal/person per day overall. With a 250-gal water tank, this gives a base cruising capacity of two days for two people. A 500-gal tank would provide the same for four people. A [[Watermakers|watermaker ]] would have to supplement this for extended cruises.
[[Category:FreshwaterSystems]]