12vdc Reverse Osmosis / UV Filtration - Not Watermaker

[Sea Conquest]

Originally Posted by Dockhead

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.

I understand that, but it just isn't in the budget at present. Of course, donations are welcome. ;-)

I know not everyone doing coastal cruising has a watermaker, so do people just take their chances with the local water supply around the world or only drink/clean dishes with bottled water?

[CarlF]

While I agree a proper watermaker would be better, I think one of the home R/O units on ebay with UV would work. These are around $250. There are several vendors. Be sure to also get one that has an auxiliary pump. Boat pressure isn't strong enough. I would explain the situation to the Ebay vendor in an email and see what they suggest.

Hook it up so the reject water goes back in the boat tank. Otherwise you'll use a lot of water. These come with a five gallon (or so) tank that holds the product water. These are cheap steel but they'll last long enough (and it's cheap to buy another one if it rusts out).

Both the UV and the pump will want 110v but they use very few watts. Just buy a little portable inverter if you don't have one.

You might also look at this standard filter as "belts and suspenders":

KX Matrikx Ceramikx 20-250-190-975

The Ceramikx Filter is NSF/ANSI Standard 53 and 42 Tested & Certified to Reduce or Remove:

• 99.95% Cryptosporidium
• 99.95% Giardia
• 99.95% Entamoeba
• 99.95% Toxoplasma
• Particulates Class I
• Turbidity
• 95% Chlorine Taste & Odo

It only costs $15 on the internet. It's .2 micron so it clogs quite quickly if you don't have other filters upstream but at this price you don't feel too bad.

Carl

[bstreep]

Frankly, a home RO unit probably isn't the best solution here. If you dump the wastewater back into your tank, you will soon have a tank overloaded with minerals.

Yes, it will eliminate ALL bacteria and viruses - assuming it's set up right (many of these units "fail" because of a poorly seated membrane). BTW, there's no way ANY bacteria or viruses can penetrate this membrane - they are millions of times larger than a calcium carbonate molecule or a sodium ion. They are designed to remove Dissolved solids.

You might also look at aquarium UV units. They are designed to run in a saltwater environment, and you should be able to find one that runs on 12v - they usually have a transformer on them.

[GordMay]

Originally Posted by bstreep

Frankly, a home RO unit probably isn't the best solution here. If you dump the wastewater back into your tank, you will soon have a tank overloaded with minerals...

And rejected bacteria & virus'!

[CarlF]

That "reject" water is going back into the same tank it came from. If there is anything bad in the reject water, there's much more of it still in the 500 gallon tank. The less than 5 gallons of good product water taken out by the R/O is not going to materially change the concentration of the bad stuff in that big tank.

Accumulation isn't likely to be a problem because most of the water is used for things other than drinking water.

If there's water to spare (like in a marina) then certainly dump the reject water. And a proper salt water R/O would be better but it could cost 20 times as much. This is pretty good bang for the buck.

Carl

[Dockhead]

Who said you're going to put the reject water back into the tank?! I would dump it overboard for all the reasons stated above.

The thought is horrifying, I know, to the cruising sailor who saves every drop of fresh water, but I think it makes sense. But we're just making small quantities (relative to total fresh water consumption) of drinking water, just a few liters a day. So we're not talking about a very big quantity of waste water.

Another problem, however, is noise and power consumption of the water supply pumps, while this process is going on.

That's why I wish we had even one person to tell us about real experience. It's odd that no one seems to have tried it.

[s/v Jedi]

Originally Posted by bottleinamessage

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).

Same here, the SeaGull filter is all you need and very convenient. It meets EPA Microbiological Guide Standards for removal of bacteria, cysts and viruses.

This link shows a bad deal but a good picture and description: Amazon.com: Seagull IV X-1F Drinking Water Purifier - Residential Model: Home & Garden

cheers,
Nick.

[Scott730]

OK lets talk about how much waste water there will be. I have 3 RO systems at my home (2 are for my Aquariums) and a spectra water maker on my boat.
First you would need to have a pressurized 4 Gal holding tank for the "good" water otherwise it would take forever to fill a glass directly from the unit. To make the 4 gals you will run the RO system for a good hour, which means you will have to run the fresh water pump all that time, you will reject easily 35 gallons to get the 4 gals.
Your considering pumping that reject water over the side? You must have very large water tanks if your willing to toss 35 gals overboard.
So your running down the batteries, dumping gals of water overboard (expensive if your buying water at say 50 cents a gallon), and putting hours of wear and tear on your fresh water pump.
If you can't affort a good watermaker, then your better off with the SeaGull filter or buy bottled water for drinking.

[Sea Conquest]

If we go with the Seagull, they seem to have several different models, ranging in price fromm $500 to $1000. Would we only need to filter the drinking water (ie have a separate faucet) or should we consider filtering all the water, so that nothing gets on our pots and pans in the kitchen sink/dishwasher (yes, we have a dishwasher aboard) or, say, our toothbrushes from the water in the head sink.

It seems that if we just filter a separate faucet in the kitchen, we could still get sick from other sources.

Thanks so much for all of your helpful info. This thread has been very informative.

[Hud3]

There's a less expensive alternative to the SeaGull IV that is capable of using the SeaGull IV filters. It's called the PurestOne water filter system. I haven't used it.

Purest One

[hellosailor]

Seaquest, some folks do a final rinse on the pots/pans/plates with some water from their tanks with a shot of bleach in it. As a final rinse (after a saltwater or raw water wash) it will certainly leave them disinfected and clean, while using a minimum of any potable water.

With a dishwasher...Well, I don't know, I don't have galley staff. How good is your dishwasher at following your instructions? <G>

[Dockhead]

Originally Posted by Scott730

OK lets talk about how much waste water there will be. I have 3 RO systems at my home (2 are for my Aquariums) and a spectra water maker on my boat.
First you would need to have a pressurized 4 Gal holding tank for the "good" water otherwise it would take forever to fill a glass directly from the unit. To make the 4 gals you will run the RO system for a good hour, which means you will have to run the fresh water pump all that time, you will reject easily 35 gallons to get the 4 gals.
Your considering pumping that reject water over the side? You must have very large water tanks if your willing to toss 35 gals overboard.
So your running down the batteries, dumping gals of water overboard (expensive if your buying water at say 50 cents a gallon), and putting hours of wear and tear on your fresh water pump.
If you can't affort a good watermaker, then your better off with the SeaGull filter or buy bottled water for drinking.

I guess that there's nothing much to say to that. So much for the domestic RO idea. Seagull it is.

[anjou]

I would bite the bullet, go for the RO and cover all bases in one hit.

[Scott730]

AdamHart
As I've said in past posts, there is no way to economically use a house RO system to purify Sea water for drinking. I do not believe your claims. Anyone who thinks they can use a standard house system needs to speak to an expert in the field before buying one.

[Tellie]

Originally Posted by Scott730

AdamHart
As I've said in past posts, there is no way to economically use a house RO system to purify Sea water for drinking. I do not believe your claims. Anyone who thinks they can use a standard house system needs to speak to an expert in the field before buying one.

Scott is correct. There is no way any house RO system is going to work to desalinate water.