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→Calculating Water Capacity
= Water Capacity =
Standard estimates of water consumption for yachtsmen yachters assume a certain austere lifestyle. But everyone’s comfort level is different.
== Design Considerations ==
There are many estimates of water consumption available for yachtsmenyachters. But it is better to start with first principles when designing your system. If your boay is intended as a live-aboard in all seasons, while remaining qualified as a passagemaker, getting the heating, air conditioning and water systems right-sized is critical from a comfort and energy-efficiency aspect.
In the water system, this comes down to how much hot water do we need in a day. We don’t need that much for drinking and cooking. The difference is in life-style usage. Everyone’s comfort level will be different. The criteria for a live-aboard are different from a weekend cruiser or racing yacht. Living aboard, we should always have hot water when we need it; not waste water; and conserve energy.
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.
Other capacity recommendations for hot water tanks range from 7 gal per person to as high as 17 gal.
In tests in my apartment taking showers not baths I the observed a daily consumption of was about 40 gal. Taking a bath (52-in bath) quickly jacked the number up into the NRCan realm. These are the results of the tests:
* Bathing
* Dish washing 4 gal/d (4 @ 1 gal)
* Laundry 2 gal/d (pro-rated from 14 gal/week)
* Hand washing 2 gal/d (4 @ o0.5 gal)
* Drinking 1 gal/d (mostly Twinings Earl Grey tea)
* Cooking 0.25 gal/d
* Household cleansing 0.25 gal/d
The drinking consumption might surprise you. For years -- [http://www.onemedical.com/blog/live-well/daily-water-intake/ well, since 1945!] -- the health community has been erroneously fixated on eight 8-ounce glasses of pure water per day.
The [http://iom.nationalacademies.org/ Institute of Medicine], which was responsible for the 1945 study, now liberally recommends a total daily water intake of 3.7 liters (0.97 gal), from all sources including water, wine, beer, coffee, tea, soda.
== Reduce Consumption ==
== 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]]