Watermakers and Harbors

[44'cruisingcat]

Originally Posted by a64pilot

I don’t think anything gets by, including a virus, which is tough to believe cause I think a virus is the smallest life form there is?

Not so hard to believe when you realize that the membranes stop 99.9% of salt molecules. NaCl. Two atoms. By comparison a virus is huge.

[Rainman]

If salt isn't getting past the membranes, biologicals aren't either. RO systems will be putting clean water into your tank. If you want to worry about bacterias and viruses, worry about what might be growing IN your tank. Add the extra filters to the water you draw out of the tank.



We often run Rainman systems up harbours or estuaries for boat shows or demonstrations. People are amazed they are drinking water from the location we are pulling water from. If it's really bad, we might get through a prefilter in day, but the product water will still be quite drinkable. Having said that, I would take a conservative approach and not run the watermaker if you have oil floating on the surface around you. Although petrochemical floats and you are drawing water from underneath, I don't like pushing my luck.

[CelticQuest]

Hi. I have a Spectra watermaker and have had no serious problems in the Caribbean. My general rule of thumb is that if you can see the bottom, then you can make water. However , the filters will foul if there is a lot of silt in the water from a river or stream. But like the other respondent, I make if when off-shore when possible.

[mikereed100]

Originally Posted by gRider

made me think of an article I was reading awhile back about dirty water in Rio. At least one expert says viruses live in saltwater. Not as much for bacteria.

"bacteria tend to break down in salt water, so there's a lower risk of bacterial infections, Muñiz Crim said.
In contrast, "Viral organisms can persist in the salt water and the sand for days, weeks and months," Muñiz Crim told Live Science."
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Our Brazilian friend is quite wrong about this. Not only do many bacteria survive in salt water, including some bad players like Staph, Pseudomonas and Vibrio species, there are many bacteria that prefer it. They are known as "halophiles" or "salt lovers". Consider that human blood has roughly the same salinity as salt water. Wouldn't it be nice if it were toxic to bacteria?

The same is true of viruses. There are thousands of viruses in every drop of water, fresh or salt. They are not picky. Don't do what my Mom used to tell me and wash your cuts in salt water.

As has been pointed out earlier, this is all academic with concern to watermakers as the water they make is essentially sterile.

[billknny]

Originally Posted by a64pilot

I don’t think anything gets by, including a virus, which is tough to believe cause I think a virus is the smallest life form there is?
As stated hydrocarbons is the issue, not so much for you, but for the membranes.
What Does Reverse Osmosis Remove? –Â*Pure Water Products, LLC

I think smallest virus is .004 microns where an RO membrane is .001 microns

I used to run industrial RO units to make sterile water for pharmaceuticals, so read and learn...

Yes, an 100% intact RO membrane will give you sterile water... BUT....

Do you know your membrane is 100% pinhole free? No you do not. Do you know that the end seals are 100% effective and allow 0% of the feed water to bypass the membranes? No you do not. Do you think those the odds are good you will not get Hepatitis from the marginally treated water in that harbor? Are you feeling lucky?

Your watermaker is designed to make water with a salt content low enough to drink. The membranes and seals have NOT been tested to prove that NO leakage occurs. You can not count on your membrane making sterile water unless you have personally run a bubble point test to show there are no leaks.

If you are going to be making fresh water from microbiologically suspect salt water, you need to either treat the product water with chorine, or use a UV sterilizer, or wait until you are someplace else.

The person quoted in the OP seems rather ignorant of what cruising is about. Yes, if you are going to live full time anchored in a crowded, polluted harbor, then you won't want to use your water maker, and it would be a "waste of money". But that's not cruising, that's squatting. Cruising is about moving around. When you are in open ocean, you make water to fill your tanks, when you are in a crowded, polluted harbor, you draw down your tanks. Honestly, as we cruise around we tend to avoid crowed, polluted harbors because... well just because!

That's only one reason why I argue with people who say if you have a water maker you can dramatically downsize your water tanks. We have 1000 liter of fresh water storage and a 50 liter/hr watermaker and they work well together. 1000 liters lasts us well over a month if we stop in a place we can't make water.

Another reason to not run a watermaker in a harbor: Most harbors tend to have water that has a high loading of suspended solids. They will very quickly clog your prefilter. (You do have a 2 micron prefilter, right?) The Chesapeake Bay is a good example. It is not polluted, but it is an estuary rich with sediment and algae. You can make clean water from it (in most places) but you will clog your prefilter in a very short time.

[billknny]

Originally Posted by Lepke

Oil is heavy, so when detergent is put on oil it sinks to the bottom. I've been drinking ship and boat made water, off and on, for my whole life and I'm 69 and still healthy. I've had my water tested several times and never had a bad test. I only use water I've made because many coastal water supplies have salt and other contaminates along with poor taste.

Say what??? Oil is NOT heavier than water--ever. You can get it to mix with water by adding detergent, but emulsified oil and water WILL kill your RO membrane right quick..

But I do agree with the taste comment... we lived on RO water only for over a year. When visiting back on land all the tap water tastes "off"

[scarlet]

so, for those that are mentioning a "pre-filter"... I'm assuming that is similar to our pond set up... it's basically mechanical removal for larger things like the grass, weeds, etc... correct? In regards to the UV filter.. I'm very familiar with those as well.. In our pond set up.. we use it to kill algae.. In a water maker set up.. does that come BEFORE the membrane? So, between the prefilter, and the water maker.. right?

And, if you want the water to be extra safe.. you could add chlorine to the tank. But, then, I'm assuming you would need another filter at the tap to remove the chlorine. is that correct?

Also.. for those who have added a filter at the tap... does it make a big difference in the taste? It sounds like there is little to NOTHING that would get past the RO membrane.. so would the tap filter even do anything? or is it waste of money?

[mark_morwood]

A pre-filter is usually 2 microns to filter out sediment, plankton, algae etc that might clog the membrane. It is there to protect your expensive membrane.

I've not heard of people using UV filters in conjunction with RO water maker, but I guess it is possible.

Be very careful adding chlorine to your water tank if you have an RO filter as it is bad for the membrane, and many systems use a little tank water at the end of the process to flush the membrane.

I don't see much point in an extra filter at the tap, but if your tank is suspect it can't hurt. The water from the watermaker has little flavour so the tap filter is not going to change that.

Assuming you start with a clean water tank, I see no point in extra filters or sterilization if you are filling it from the water maker. The few times we topped up water from a dock we did run it through a carbon filter on the end of the hose before the water got to the tank.

[billknny]

Originally Posted by Rainman

If salt isn't getting past the membranes, biologicals aren't either. RO systems will be putting clean water into your tank. If you want to worry about bacterias and viruses, worry about what might be growing IN your tank. Add the extra filters to the water you draw out of the tank.

I am sorry, but you are wrong, and telling people things that are potentially dangerous. Follow along for a minute before you decide I don't know what I am talking about...

A typical desalination system is rated for 95% salt rejection to make good, drinkable water. A new membrane should be very close to 99.5% rejection.

So... if I had a small hole in my membrane that leaked at a rate equal to 4% of the output water flow, I would still be making water in specification for the unit--it would pass any conductivity test I care to run--but it would contain 4% raw, unprocessed sea water and all the virus and bacteria that go along with it. The same thing can happen from a tiny leak at the o-ring seals at the end of the membrane. I assure you, you would never know such a leak was there.

Before you tell me it can't happen on YOUR RO system, you need to know that when testing installed membranes for pharmaceutical application about 20% of them FAIL the test to show leaks like this, and that is with units designed from the start to make sterile water.

This is why UV sterilizers are used in some RO units, or why smart people chlorinate their tank water if they are in places they are concerned about the water quality.

If a salesman is telling you that HIS RO unit will make sterile water no matter what the inlet water is like, find another brand to buy. He either doesn't know what he is talking about, or he is being deliberately misleading, or both.

Yes, chlorine is bad for membranes, and tank water is used to flush the membrane, but a simple carbon block filter in the flush line will remove chorine to the point it is safe for the membrane.

[donradcliffe]

Your body doesn't need perfectly sterile water.

RO water is more sterile than the water that comes out of most municipal taps.

I added a 1 micron carbon filter to the tap for water from other sources, like tapwater, springwater, and rainwater.

[pdstokes]

Originally Posted by billknny

I am sorry, but you are wrong, and telling people things that are potentially dangerous. Follow along for a minute before you decide I don't know what I am talking about...



A typical desalination system is rated for 95% salt rejection to make good, drinkable water. A new membrane should be very close to 99.5% rejection.



So... if I had a small hole in my membrane that leaked at a rate equal to 4% of the output water flow, I would still be making water in specification for the unit--it would pass any conductivity test I care to run--but it would contain 4% raw, unprocessed sea water and all the virus and bacteria that go along with it. The same thing can happen from a tiny leak at the o-ring seals at the end of the membrane. I assure you, you would never know such a leak was there.



Before you tell me it can't happen on YOUR RO system, you need to know that when testing installed membranes for pharmaceutical application about 20% of them FAIL the test to show leaks like this, and that is with units designed from the start to make sterile water.



This is why UV sterilizers are used in some RO units, or why smart people chlorinate their tank water if they are in places they are concerned about the water quality.



If a salesman is telling you that HIS RO unit will make sterile water no matter what the inlet water is like, find another brand to buy. He either doesn't know what he is talking about, or he is being deliberately misleading, or both.



Yes, chlorine is bad for membranes, and tank water is used to flush the membrane, but a simple carbon block filter in the flush line will remove chorine to the point it is safe for the membrane.

Someone who knows exactly what they are talking about! Thank you.

[Rainman]

billknny: I understand your points and agree to an extent. If a membrane or O-ring develops a tiny leak so salt is only rejected at 95%, biologicals may possibly get through with that seawater. This is why I suggested filtering water on the way out of the tank. That way you are covered if anything is growing in the tank or leaked into the tank through a faulty RO system. I agree chlorine is a good option as well.

I also agree with you that anyone saying that their system can not possibly fail is going to be lacking credibility.

Having said that, you indicated that watermakers are typically rated for 95% rejection. if you are operating in seawater at about 35,000ppm and rejecting only 95% of salt, then your product water will be about 1,750ppm. That is easily detectable by either your tongue or a hydrotester, and should not be used. I don't know of any watermaker company that would be happy with their customers getting those results.

Membrane production reliability may have improved since you were doing your work with 20% membrane fault rate. In the last 800 Filmtec SW30 membranes we have installed in our systems, we have only had 11 (1.4%) that didn't pass our internal TDS tests. We pull those out and swap them before shipping. My apologies if I misunderstood your comment about 20% membrane test failure.

[scarlet]

Are there test kits that you can use to test your water quality for things like salt content and bacteria, etc? I would think that regular testing of the tap water would be a great way to be certain... We are still in the process of looking for a boat, and I would like to know, with certainty, that the water in the tank is not tainted before I drink it. You never know what a previous owner did, or didn't do.

[kenbo]

To Billknny

You can not count on your membrane making sterile water unless you have personally run a bubble point test to show there are no leaks.

Is there a way to run this bubble point test on a yacht RO system in a cost efficient manner?

[Stu Jackson]

Originally Posted by scarlet

Are there test kits that you can use to test your water quality for things like salt content and bacteria, etc? I would think that regular testing of the tap water would be a great way to be certain... We are still in the process of looking for a boat, and I would like to know, with certainty, that the water in the tank is not tainted before I drink it. You never know what a previous owner did, or didn't do.

Of course there are. I'll let the users fill you in.

What a PO may or may not have done to the domestic water system has nothing to do with watermakers.

You should obtain Peggie Hall's book to read about how to treat the tanks and pipes in your system before you set off. And to maintain them as you go.

https://shop.sailboatowners.com/prod...+of+Boat+Odors