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thomaswaier · 22-02-2010, 06:52

Good morning all,
We have been considering installing a watermaker on our boat as we plan to cruise the Caribbean next winter. I have been told that watermakers are "useless" in Florida and the Caribbean because of the high amount of bacteria in the water. Watermakers remove salt but not the bacteria? I would appreciate feedback on this issue. On the surface, it seems that either this is not true or, if it is, cruisers must use additional methods to make the water potable. Appreciate your feedback on this issue.
Tom

doug86 · 22-02-2010, 06:55

... making popcorn and waiting for the replies...

edsailing · 22-02-2010, 07:00

Yes, the water is potable. Filters will remove everything larger than a water molecule - bacteria won't get through

anjou · 22-02-2010, 07:08

Salt is smaller than bacteria so nothing gets through, besides, if your still worried, pass it through a UV filter.

Sailmonkey · 22-02-2010, 07:09

You just have to be careful using them in a bacteria or virus infected area. The membranes will breed life like nothing else. I also have a recolection of viruses being able to, in some circumstances, make it through the membrane, but I have no idea where I got this from or if it even applies to RO, I may be thinking of flash evaps.

**Tellie** · 22-02-2010, 07:16

There are thousands of watermakers all over Florida and the Carribean both marine and land based. Spend any time in either place and there's a better than good chance that you've been drinking plenty of RO water. I'm not aware of any epidemic of people falling ill from drinking RO water. What I have seen is people getting ill from drinking water from the storage tanks that RO water is placed in. Even in the best of maintained tanks a good filtering system after your ships tanks is always good idea.

daddle · 22-02-2010, 07:30

I'll second Tellie's remarks above. I recall that RO water no matter how filthy the input will be pure in theory. But in practice it is difficult to keep all the components sterile. And there might be a tiny leak in some seal, a tank vent, or whatever. In a polluted environment it may be prudent to do some treatment.

Kefaa · 22-02-2010, 07:33

While they are leaning in a specific direction, this addresses your specific question.
Reverse Osmosis Water Filters and Water Purification
Compare water filters, purifiers, and purification technologies incl. reverse osmosis

In almost all cases, RO will purify the water to a level consistent with the best drinking water. However, certain virus and bacteria can make the transition under specific circumstances.

Anjou makes and excellent point in that if you feel you are entering a highly contaminated area (lots of human or animal waste, bogs or swamps), get one with a UV option. Keeping in mind that every option has a price and its more than $$$. If you get UV ensure the unit will operate even if the UV is off (like blown).

As for SailMonkey's point - follow the maintenance specs. Think food processing equipment, not fan motor. These need to be cleaned and cared for correctly and I can easily see poor care as responsible for more issues.

lorenzo b · 22-02-2010, 08:30

I drink rainwater collected off my deck that's stored in large tanks. Use just a touch of bleach if your worried, the slight odor dissipates in a day or so. Water borne diseases are rare in totally isolated systems.

barnakiel · 22-02-2010, 13:16

Watermakers are not meant to be use in port nor inshore. Offshore, they will provide high quality drinking water.

Make sure all elements, esp. filters and membranes are top quality and up to specs - I have witnessed a situation where a land based desalination plant (in Canary Islands, Spain) was providing local community with non-drinkable water because someone used non-spec membranes of a type that permitted some of the bad stuff thru ...

b.

NoTies · 22-02-2010, 17:24

Sea water membranes generally reject 99.5% of the salt whereas theoretically they should reject 100%. The reason for this is nobody has been able to manufacture the perfect membrane yet. Minute flaws are what allows the 0.5% through. A perfect membrane will not allow bacteria or viruses through but there is a VERY small likelihood that manufacturing flaws could allow passage. Typical bacterial analysis of seawater intake in coastal communities where I service desalination plants is <100 ppm. According to my calculations this, combined with the 99.5% rejection rate means a 0.0005% chance on one bacteria getting through to drinking supply. Well inside WHO standards.