Water, Water Everywhere!

Posted by Ed

When cruising we need to stay in touch with the availability of several consumable resources, food, fuel and fresh water. Eating habits become adjusted to the areas we may be visiting, such as baguettes and croissants on a daily basis when visiting the French islands. Fuel and water are both closely managed so as not to run out at the most inopportune time. Fuel can usually be managed through the awareness of how much fuel is necessary to run the engine to charge the batteries and run the engine driven refrigeration.

Water on the other hand, although tightly managed gets consumed quite rapidly through dish washing, boat cleaning, human consumption and the luxury of daily showers. Many boats have large storage capacities for water and may not worry about how much water they use between ports. Other cruisers are always looking for a dock with a garden hose to fill their five gallon Jerry Jugs or a place to pull their boat up to a dock to replenish their water supply. However, most cruisers I talk with have some type of watermaker on board and once you have a watermaker, you ask yourself how did I ever get along without one.

The basics of the way a watermaker works is through a reverse osmosis (RO) process where sea water is transformed into potable (drinkable) water. The sea water is filtered through a series of prefilters before being pumped at a high pressure (800 PSI) to the reverse osmosis membrane which removes the salt element and other impurities from the water before sending it to your water storage tank. The water that passes through a typical watermaker system discharges approximately 90% of the water as brine and the remaining 10% becomes product water or drinkable water. There are many RO systems on the market that produce anywhere from 3 gallons an hour of product water to hundreds of gallons an hour based on your needs, available space for the RO system and of course cost. RO systems have been in use for years by hotels in the island communities and among others, the island of Jost Van Dyke in the BVI’s depends almost exclusively on their RO system located in Little Harbor to supply the entire island with potable water.

The concern for most cruising boats is finding the available space for the RO system and the energy required to run such a system. We chose a Katadyn Power Survivor 160E watermaker which produces 160 gallons a day or 6.6 gallons an hour, which generally satisfies the needs of Liz and I. One of the main reasons for our choice in watermakers is due to its extremely compact size and its easily tucked away in an area that does not need to be accessed expect to service the unit when needed and its reliability. Typically we run the watermaker whenever the engine is running to charge the batteries and refrigeration.

As of today, we have logged 200 hours on our watermaker which relates to 1320 gallons of water produced by out watermaker. We love the independence of not having the need to chase down the next available water source. Water, water, everywhere!