Highly elevated zinc in RO water

[Dave-T]

I do monthly ICP tests as part of Moonshiners. In the one I just got back, zinc was highly elevated: 338ppb in my RO water, and 8.8ppb in my tank water. It's always been 0 in the RO water before, and around 1 in the tank water (I dose zinc as part of moonshiners). The only thing that has changed was the addition of a water container after the DI resins in my RO system, and that container is supposed to be polypropylene lined.

This is the tank.

Any thoughts on where the zinc could have come from? Should I be concerned?

And is there anywhere I can get a quick test done to double check this? The Oceamo ICP tests take about 2 weeks to get back. I'd like to do a test of the water both before and after that container, to determine if that's the cause. If there was a test I could do myself, that would be ideal.

 

[Randy Holmes-Farley]

and that container is supposed to be polypropylene lined.

Is it something else under the polypropylene?

Was it previously used for something else?

 

[Dave-T]

No, it's brand new. It might be zinc lined under the polypro, that's what I'm thinking. So maybe the liner has a hole in it? My maintenance guy who installed it and has used it with other clients says that it's always been fine for him, and he does do ICP tests.

I'm going to try to get it replaced from amazon.

Is there a zinc test available that I could get to check on it?

 

[Randy Holmes-Farley]

No, it's brand new. It might be zinc lined under the polypro, that's what I'm thinking. So maybe the liner has a hole in it? My maintenance guy who installed it and has used it with other clients says that it's always been fine for him, and he does do ICP tests.

I'm going to try to get it replaced from amazon.

Is there a zinc test available that I could get to check on it?

I’m not aware of any diy zinc tests.

 

[Christoph]

Hi Dave,

i would also expect the water tank (or anything that was used to connect the tank to your RO system) has a zinc surface exposed to the water. Zinc is not an issue whatsoever for drinking purposes - so equipment manufactured for drinking water purposes does not really focus to be "zinc free".

Our measurement here is highly significant, so you can be 99,9% sure the zinc is real and not any sort of measurement error.

Best regards,
Christoph

 

[Tom1975]

I had the same Problem with Iron. It did get higher and higher in my icps for about 6 months. I couldnt find the source of it. Then the zinc startet to geht Higher. I still didn't know why. In November Last year WE had suddenly no more water in the house an the reason was a rupture of the water pipe from the street to our house. Our house was built in the 1940s. When we bought it we didn't change the pipe. I use osmosis with a big Filter of resine (5litres) and i Change IT every 6 months. The waterpipe was Changed by a special company. The old pipe was completely rusty. From that Moment zinc and Iron dropped to normal Levels. Why i didn't had this Problem before? I think the Line was rusty for years but at the place where the Line finally broke there was a huge intake of those two elements into the water which oversatturated m'y system...

 

[Dave-T]

I’m not aware of any diy zinc tests.

How about this?

Zinc Test Kit- HI3854

The HI3854 is a chemical test kit for the determination of zinc using colorimetric determination with a zincon reagent.

www.hannainst.com

 

[Dave-T]

How about this?

Zinc Test Kit- HI3854

The HI3854 is a chemical test kit for the determination of zinc using colorimetric determination with a zincon reagent.

www.hannainst.com

Never mind. That's not accurate enough.

 

[Joekovar]

I don't know if zinc would come out, but I do remember those things are supposed to be filled and drained completely once or twice before putting them into use. If you're unaware of that.

Possible sources of contamination.

A zinc coated fastener/part found it's way into the line between the DI unit and the tank. Solution would be to close the valve on the tank, disassemble the line feeding the tank, and inspect it. If nothing is found, invert the tank so the spout points down and shake it lightly, the point being to let gravity pull anything in there towards the spout, open the valve and allow 1/4 gallon or so to flow out into something you can inspect for anything that may have come out.

Shavings from construction. Same idea as fasteners/parts.

Diaphragm attachment failing. Without cutting that unit open, I'm not sure whether they coat the entire inside with polypropylene, or only the portion that should be coming into contact with water. If they don't coat the entire inside, the diaphragm is attached at the line where the coating ends, and human error placed that diaphragm too far in the uncoated direction or missed a spot of adhesive, there could be exposed surface metal and the attachment is working on failing. There's no practical way to check this other than monitoring elements in the water over time and seeing other metallic elements show up once a zinc coating has been eaten through.

Hole in the diaphragm. You should see performance significantly different than expected if there's a hole in the diaphragm and no polypropylene coating on the dry side.