R/O
Reverse-Osmosis (R/O) is not a new technology. In fact, large R/O plants have provided drinking water from seawater for a large portion of the world’s population for several decades. It has only been in the last fifteen years or so, however, that RO systems became small enough, reliable enough, and energy efficient enough to be considered standard gear on cruising boats. An informal survey among our CRUISING friends indicated that more than 50% now have a Watermaker installed, and an overwhelming majority of those who don’t - wish they did. The major problem with using R/O Watermakers in Harbour is primarily Petrochemical Pollution (Oil, Gas, Fuel, & some other chemicals such as Chlorine*), which will destroy the membrane.* Chlorine tolerance is usually < 0.1 ppm. Unless there has been a major oil spill, and/or the surface is churned up, any petroleum product that might be in the harbour water will float well above the intake points of most installations.A dissolved salt molecule is smaller than any bacteria, and most (known) viruses, hence the R/O Membrane is very effective in rejecting these microbiological contaminants - effectively purifying contaminated water*. Upon learning that I was installing an R/O Watermaker, our family Doctor recommended that we never use Municipal water again (even in North America).* In addition to boiling, Reverse Osmosis (RO) systems are recommended by the Centers for Disease Control as the most effective way of treating potable water. We used a Sea-Srainer to elliminate “grit” & grass etc. (solids), and then a 20 micron fabric pre-filter, feeding a 5 micron Activated Carbon filtre (to reduce contaminants such as chlorine, pesticides and organic chemicals, and to eliminate tastes and odours).Notwithstanding it’s poor reputation with cruisers, we happily used a PUR “Powersurvivor-35" for nine winters. It faultlessly provided ALL of our water (over 50 - 60 months use - perhaps 4,000 gallons of product water). We Pickled each spring (first pre-flushing with at least 10 gallons of R/O water).I’ve also installed (in no particular order of preference): Village Marine-Tec, Watermakers Inc., Spectra, Sea Recovery, Offshore Marine Lab’s, (... more ?) - all of which appeared to be high-quality equipment. I'll defer to others, regarding the capabilities & reliability of specific brands IN USE.Some Criteria for Selecting a Watermaker:1. The first step in choosing a watermaker is calculating your anticipated water consumption. Gallons/Day Water Budget:Couples generally require: 3-5 Gallons/Day up to 6-8 GPDCrew of 3-4 requires: 6-10 GPD up to 12-16GPDI recommend choosing a model that can produce your calculated daily water needs in 2 to 4 hours of operation per day (or less), depending upon your available power.Ratings to Compare (between differing units): EFFICIENCY Amp/Hr per Gallon (12 VDC): Watt/Hr per Gallon: Current Draw (12 VDC):Size, Space, & Weight (Modular or Packaged):As a cruiser, you will spend more time maintaining your boat than you will on passagemaking, touring, or any other of the glamorous components of long-term sailing - so be certain that the equipment you chose (& the way you install it) is maintenance & repair “friendly”. Make it easy for “the next guy”; for you are likely he.HTH,Gord