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Old 15-05-2009, 16:34   #1
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12vdc Reverse Osmosis / UV Filtration - Not Watermaker

Can anyone recommend a reverse osmosis system with 12 volt UV filtration. We are heading to Mexico with our newborn babe and a nursing mother, so we would like to avoid the stomach bugs if possible. All of the RO systems we are finding use 110 for their UV filtration. Thanks!
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Old 15-05-2009, 17:14   #2
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I'm not exactly sure what you mean by an R/O unit that isn't a fresh water maker. This company apparently has 12v light units however.

WaterFixer Water Filters And Purifiers Model 500
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Old 15-05-2009, 17:35   #3
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Meaning, I am not looking for a $4,000 watermaker. You can pick up R/O systems these days for a very reasonable cost. I don't need it to desalinate seawater. We just want to highly filter our very old (and somewhat scary looking, IMHO) aluminum water tanks so that we can drink from it without fear (especially with a baby).
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Old 15-05-2009, 17:47   #4
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I understand. The UV treatement is separate from the R/O process. With R/O the trick on board is generating enough pressure. You shouldn't normally need both systems. My experience in Mexico was that getting decent water for the boat wasn't that big of problem. If you have bad tanks they usually can be cleaned and/or treated. There are some links you can find about making your own R/O watermaker as well.
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Old 15-05-2009, 21:44   #5
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Looks like that web site can deliver all the parts for a 12V UVC light (lamp, tube, ballast) for under $100 and considering the 12v ballast is half of that, that's not unreasonable. Of course, the enclosure for the bulb is way more, but that's usually because it takes some work to enclose a light bulb in water--and reliably keep the water and electricity apart.

If you can't find something cheaper, $400 will buy an awful lot of iodine and chlorine, and that will disinfect water just as well. Or, a hundred bucks will buy a Steripen, but that only treats a pint or so at a time. (Use it in the glass/bottle before drinking.)
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Old 15-05-2009, 23:56   #6
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I think i know what you mean.
In Asia they are called Aquaguard often. Often they use the Akronym RO but most of them are not really a reverse osmosis system.
They are normal filters and then "sterilize" the water with UV.

You could also just boil the water. Thats the cheapest option.

Here in India we use such an aquaguard for the water to wash salads etc. Many people have problems after drinking tap water.

For the baby we still boil even the bottled water.
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Old 16-05-2009, 03:18   #7
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I'm also interested in this question. We us an undersink reverse osmosis system at our country house to treat highly mineralized well water. The water that goes in is hard, nasty-looking, -smelling, and -tasting, and i red with dissolved iron. What comes out is pure, perfectly soft, and tastes and smells great. Like magic. The membrane is changed only every two years or so, and a complete change of all of the filters costs only $150 or so. If you believe the data sheet, it removes all viruses and bacteria besides the minerals.

It seems to me that something like this would be fantastic on the boat. It would eliminate the need to carry expensive bottled water.

Anybody try it?

For anyone confused about the RO process: the household undersink jobbies use the exact same process as your watermaker. The difference is that to get seawater through an RO membrane takes about 100x the pressure, compared to getting tap water through a membrane, so a watermaker looks very different, with its pressure vessels, high pressure pumps, etc., from an unsink RO unit. I would guess that your watermaker membranes might be more porous, also, than in the household units, in order to maximize throughput (the household units work continuously using just water pressure, and they only produce a liter an hour or so, so they can afford a less permeable membrane, I am guessing).
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Old 16-05-2009, 04:03   #8
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... If you believe the data sheet, it removes all viruses and bacteria besides the minerals...
...the household units work continuously using just water pressure, and they only produce a liter an hour or so, so they can afford a less permeable membrane
They won't remove all pathogens, just the larger one; because they have a more permeable membrane.

A desalinating R/O watermaker membrane will not pass a dissolved salt molecule, which is smaller than most bacteria & virus’ - hence it will also filtre those larger pathogens.
A household freshwater R/O filtration unit will pass a salt molecule, and will also pass the smaller bacteria & virus.
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Old 16-05-2009, 05:16   #9
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We got tired of lugging bottled water for drinking and installed a General Ecology SeaGull IV filter. They are certified to remove >99.9999% of bacteria, >99.9% of cysts and >99.99% of viruses. Here's a quote describing the testing process:

Quote:
The purifiers were operated for 100% of their rated capacity and challenged periodically with high concentrations of bacteria, cysts and virus. At the 60% and 75% test points the units were challenged with "worst case" water according to protocol. Additionally, the systems were allowed to stagnate for 48 hours after the 50%, 75% and 100% test points to demonstrate that no microbiological growth through the cartridge occurred.
They also have a carbon filter component to remove organics and bad smells and tastes.

Here's a link: SeaGull IV test results.

They're fairly pricy, but worth the peace of mind to my wife and me. There may be similar products made by others on the market now, so you might want to Google around and see what you can find.
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Old 16-05-2009, 06:46   #10
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They won't remove all pathogens, just the larger one; because they have a more permeable membrane.

A desalinating R/O watermaker membrane will not pass a dissolved salt molecule, which is smaller than most bacteria & virus’ - hence it will also filtre those larger pathogens.
A household freshwater R/O filtration unit will pass a salt molecule, and will also pass the smaller bacteria & virus.
I tried to find concrete technical data on this but could not get a definitive answer. I did find some technical information on the Dow website. Dow makes most RO membranes in boat watermakers and also in household undersink RO units. The data on the website suggests that a home RO system has 98% "stablized salt rejection" while a marine watermaker membrance has 99.4% "stablized salt rejection". See: Marine and FILMTEC TW30-1812-24.

This does support your idea that home systems are MORE, rather than less permeable than marine systems, but does seem to contradict your idea that "a household freshwater R/O unit will pass a salt molecule". Bacteria and viruses seem to be LARGER than salt molecules, and a lot of other information, at least claims of manufacturers, seem to indicate that household RO units do block viruses and bacteria.

Doesn't look to me like there is so much difference between watermaker RO process and household RO process except that the very high osmotic pressure difference between seawater and fresh water across a membrane demands tremendous pressure to create a reverse osmotic flow, whereas the low osmotic pressure between tap water and pure water across a membrane will allow reverse osmotic flow to be created with much less pressure.

But maybe someone has a better understanding? And most of all -- anyone use a household RO system in his galley? Practical experience?
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Old 16-05-2009, 06:51   #11
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We got tired of lugging bottled water for drinking and installed a General Ecology SeaGull IV filter. They are certified to remove >99.9999% of bacteria, >99.9% of cysts and >99.99% of viruses. Here's a quote describing the testing process:



They also have a carbon filter component to remove organics and bad smells and tastes.

Here's a link: SeaGull IV test results.

They're fairly pricy, but worth the peace of mind to my wife and me. There may be similar products made by others on the market now, so you might want to Google around and see what you can find.

That's exactly what the boat came with -- a Seagull IV. Maybe it's good enough. But it only filters to something like 0.5 microns (compared to apparently 0.0005 microns for household RO), so I thought that an RO unit might be much more effective.
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Old 16-05-2009, 06:54   #12
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You might want to look at the "SeaGull" waterfilter..I installed one a couple years ago and wonder why I didn't get one years ago. The kit with fawcet and hoses sells for around $300. Filters are $75. and good for a year or more. Water is pure and tasteless. (I have no affiliation with the company, just a very satisfied customer).
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Old 16-05-2009, 11:11   #13
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As we sailed around the world, there was never a day that we didn't find trash floating in the water. It's everywhere.

In the Tuamoto Archipelago of French Polynesia, the windward side of the atolls are like trash bins catching every kind of non-biodegradable debris imaginable. It was shocking to see.

Holding tanks and composting toilets are a band-aid on the real problem of human pollution and waste. Overboard discharge of human waste is an easy target for lawmakers who don't want to deal with the real problems of human pollution.

In America, our water supply is so polluted with drugs and chemicals that the government is suppressing the truth from the public. People and the pharmaceutical industry flush trillions of pills down the toilet each year, and our water table fills up with drugs. In many places, pure water does not exist. Water is a cocktail laced with dozens of drugs that made it down to the water table.

Discharge of untreated waste into the water is bad. I wish that was the real and most serious problem that faced us. I would take that problem any day over a nation so addicted to chemicals that the water supply is no longer safe.
The above is from Composting Toilets and is germane to this thread, too, I think. It's post # 38 in that thread.

Dave is a well-respected doctor, circumnavigator and contributor to this Forum. It would be interesting to hear his opinion on whether RO can filter out the pharmaceutical poison in tap water.

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Old 16-05-2009, 14:46   #14
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SeaGull Water Filtration

We looked at the SeaGull -- it sells for around $600 on Defender (not sure where someone picked it up for $300). Does it really get out all the bacteria, molds, yeasts, viruses and cysts? We are trying to avoid the diarrhea and other stomach bugs you typically get in Mexico. Things like e. coli, giardia, cryptosporidium, etc. My understanding is that RO is not enough, you need UV purification on top of it to kill the microorganisms. Our plan is to install the RO plus UV system in the galley and have it filter the water coming out of our 500 gal. tanks (which we will get from the local tap when we are at shore). We will eventually get a watermarker, but don't have it in the budget at present, so were hoping to install the undersink RO plus UV system in the meantime.
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Old 16-05-2009, 15:34   #15
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We looked at the SeaGull -- it sells for around $600 on Defender (not sure where someone picked it up for $300). Does it really get out all the bacteria, molds, yeasts, viruses and cysts? We are trying to avoid the diarrhea and other stomach bugs you typically get in Mexico. Things like e. coli, giardia, cryptosporidium, etc. My understanding is that RO is not enough, you need UV purification on top of it to kill the microorganisms. Our plan is to install the RO plus UV system in the galley and have it filter the water coming out of our 500 gal. tanks (which we will get from the local tap when we are at shore). We will eventually get a watermarker, but don't have it in the budget at present, so were hoping to install the undersink RO plus UV system in the meantime.
The more I think about it, the more I think that you would better spring for the watermaker and drink that -- made from pure sea water -- than try to adapt the nasty tap water of most of the world. In the long run it's got to be better, and more efficient.
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