If a man must be obsessed by something, a boat is as good as anything, perhaps better than most E.B. White
Something often taken for granted by all of us is the availability of clean water. One of the issues while living aboard, especially while cruising is that you do usually have a limited supply while away from the docks.
My wife and I use 12 gallons a day, or enough for 25 days without refilling aboard our trawler, the Patricia Ann. Our usage includes bathing, and preparing meals. That's with a 300 gallon water tank. Naturally, conservation is the key while living aboard a boat; no standing in the shower for 30 minutes. You can determine your daily use on your boat by timing the filling of a 5-gallon bucket, then timing the filling of you water tank. Simply divide the time it takes to fill your tanks by the time it took to fill your 5 gallon bucket, and then multiply by 5 gallons and you have the amount of water you have used since last filling.
Tank fill time / Bucket fill time x 5 gallons = Total water use
Shore Water
You must be sure of your water quality as well. While cruising, you never know what quality your water will be. You will not know whether the water you will be using is city water or well water. And if it is a marina well, had it been properly treated. Several months ago, our marina had a well problem at the well head causing the water supply to become contaminated with e coli bacteria. It took over a week to get it cleared up. Some of the marina locals must surely have used the water before the problem was discovered.
However on the Patricia Ann, we had ample safe drinking water. We have a 5 stage filtration system that provides bottle-like clean water from any questionable source. Water goes through 2, 5-micron filters, then a single 2-micron filter, and a carbon filter to remove cysts and undesirable tastes. Then finally a UV radiation light to kill any bacteria before it enters the holding tank. The power source is 110 volt ac but can be changed to 12 volts dc. The resulting water tastes a pure as bottled water.
So what if you have just bought that used trawler and are concerned about the existing water in her tanks? Ordinary bleach will treat water suitable for drinking.
Use 1 teaspoon non scented Clorox Bleach per ten gallons of water; if the water is cloudy, double the recommended dosages of Clorox Bleach.
Rainwater
I have also seen setups on trawlers, where rainwater runoff is collected from upper decks and funneled into the holding tanks. This is pretty good source of water but there is still concern about the quality of the rain water that would affect the taste of the water and perhaps cause tank corrosion. My caution would be to be sure of the air quality in your area. If you are in a highly industrialized area that creates acid rain, I would use caution.
Watermakers
Now of course, you can install a watermaker aboard your trawler and have virtually unlimited water. All water makers designed for small boats and yachts rely on essentially the same technology, exploiting the principle of "reverse osmosis"; a high pressure pump forces seawater through a membrane which allows water but not salt to pass. The price of water makers purchased are determined by the amount of water they produce on a daily basis. If your cruising takes you to desolate islands in the Bahamas, keep in mind that water if purchased can cost as much as fuel. Watermakers are a virtual necessity.
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