UV in Watermaking Loop

[Strygaldwir]

I put a charcoal filter between my water maker and the back flush supply. This gives me some amount of safety as I do fill my tanks from shore when I am in non-cruising mode.

[Seahunter]

Originally Posted by Strygaldwir

I put a charcoal filter between my water maker and the back flush supply.

+1 Great idea.

[nwdiver]

Thanks all, I already have a UV (and charcoal) filter between my water supply and drinking tap which comes from a gallon jug in the refrigerator. I was wondering if I could reduce fouling on the water maker membrane and prefilters by killing all the beasties going into them with UV (well I know I can, the question is, ”is it viable”) I guess the answer is not really, but I’ll put a UV filter (I know they are not filters but that’s the general term for them) after my 5 micron and that will kill everything left (bacteria, viruses and diatoms) that gets that far. I’ll let you’ll know if it reduces membrane chamber fouling.

[Tellie]

Originally Posted by nwdiver

Thanks all, I already have a UV (and charcoal) filter between my water supply and drinking tap which comes from a gallon jug in the refrigerator. I was wondering if I could reduce fouling on the water maker membrane and prefilters by killing all the beasties going into them with UV (well I know I can, the question is, ”is it viable”) I guess the answer is not really, but I’ll put a UV filter (I know they are not filters but that’s the general term for them) after my 5 micron and that will kill everything left (bacteria, viruses and diatoms) that gets that far. I’ll let you’ll know if it reduces membrane chamber fouling.

You can of course do anything you want. But you'll be the first I've ever seen do it or need to. There are tens of thousands of watermakers out there that are functionig just fine without one. As this thread suggests there are people out there that tend to over think or over engineer a project. Great ideas do come about at times, but if a UV light before your membrane would any value to your watermaker the big guys would have been doing it long before with the UV lights they already carry and sell.

[Tellie]

Originally Posted by Seahunter

According to whom? UV filters for water makers are based upon the water maker's output flow rate. Putting it on the freshwater pump side defeats its flow rate design. This is based upon manufacturer design.

Well, according to me. A UV filter just before a faucet that is used to injest water from your fresh water tanks has zero bearing on a watermakers flow rate, but rather on the flow rate after a filtering system just after that filter. Apples and Oranges.



While it's true you don't want to get ANY bleach flushed through the water maker's membrane, flushing the tank with bleach and or conditioner is not a bad thing.
If a tank is propely flushed.

Many boats do not have the capability to be properly flushed because of their design and how they are mounted in a boat. Not all tanks are easily accessible. I have replaced many chemically burned membranes because the owner or worker flushed the tanks twice after adding bleach and overpowered the watrmakers charcoal filter.


Nonsense. There's a difference between air and waterborne impurities and a gangrenous mass of bacteria making it's home in your water tank(s).

"a gangrenous mass of bacteria making it's home in your water tank"? Really? If you have gangrene in your tanks a hundred UV lights on the watermaker feeding that tank won't do didley squat. I would also, with all due respect, suggest if you have a gangrenous mass breeding in your tank that you either have a serious problem were you run the watermaker and/or there is a serious problem with your watermaker. The other possibility is that perhaps a Zombie is exisiting in your tank.

[CarlF]

One of the problems with UV light at the faucet is that you have to remember to turn it on and off or the power use is unreasonable.

Instead, I've made a little recirculating system like a fuel polisher. There are a few valves that let me

a) send the watermaker product water through a filter and UV to the tank

b) pump from the tank through the filter and UV to the drinking water faucet

c) pump from the tank through the filter and UV back to the tank for "polishing" of water that's been sitting in the tank for a while or is questionable shore water. I can also pump from tank 1 to tank 2 or visa versa.

I only turn the UV on for a and c.

[Tellie]

Originally Posted by CarlF

One of the problems with UV light at the faucet is that you have to remember to turn it on and off or the power use is unreasonable.

Instead, I've made a little recirculating system like a fuel polisher. There are a few valves that let me

a) send the watermaker product water through a filter and UV to the tank

b) pump from the tank through the filter and UV to the drinking water faucet

c) pump from the tank through the filter and UV back to the tank for "polishing" of water that's been sitting in the tank for a while or is questionable shore water. I can also pump from tank 1 to tank 2 or visa versa.

I only turn the UV on for a and c.

Interesting plumbing. Seems to make a lot of sense.
Of course amp use is very important even with the low power usage.

[Cheechako]

"According to whom? UV filters for water makers are based upon the water maker's output flow rate. Putting it on the freshwater pump side defeats its flow rate design. This is based upon manufacturer design."
I guess I dont understand this statement. UV filters are UV filters. They kill stuff in the water as the water flows through. They are all rated at a maximum flow rate, whether for household use or for an RO water supply. If you really want to know that things are dead without further contamination, then just before the faucet would make sense. I think it's way overkill for an RO system though, and turning the UV on and off to save electricity is going to shorten the life of a $50 bulb extensively. Your RO water is going to be way more sterile than any household water youve been drinking most your life. If you have a 40 gal per hour water maker, that is only .66 gal per minute anyway. The smallest UV filter I've seen is about 2 gal per minute. One advantage of putting the UV filter between the tank and water maker is you eliminate the problem with hot water coming out of your faucet. (the UV filter heats the water if you are not running the water)

[phorvati]

Ive drank my water since 2006. Never had any problems but then in june 2010 Ive had cramps from drinking it. It took me about a month of observation to conclude that its from drinking the tank water. Tanks can get dirty, and accumulate bacteria. My membranes were clean. I was getting good product flow and production. I flush with product after every batch. I also take out prefilters (20 and 5 micron) and put them out to dry after every batch. Its just one of those things that are hard to track. Why was I getting cramps all of a sudden. Not much changed in production, salinity, or my habit of consumption.
That year I didnt drink my RO water. In the fall i left bleach in the tanks and winterized the membranes(both sides) in -100F antifreeze. The following season i was drinking it w/o a problem.
I would agree with your assesment that RO water right after the membrane is cleaner then your home water. But after its been sitting in the tank for few days or a week, it could get contaminated. For me its not feasible to add bleach in my tanks. My electrical budget can afford a 10W element. That's under 1A continuous 24/7. I could care less if the water gets hot. I'm sure after a bit of running it would be fine. So to me putting the UV sterilizer just before the facet in the galley seems like a reasonable piece of mind.

[sck5]

"The other possibility is that perhaps a Zombie is exisiting in your tank."

I had a dead zombie in mine but a cup full of bleach and a few flushes took care of it. Zombies hate clorox.