RO/DI...

[RR37]

So I moved and disconnected my RODI unit.

 

Left it full of water packed it up expecting to start running it a week after the move. But between renos and a new floor its been 4 months, who thinks I will need all new inserts and a membraine ?

 

The water in the columns looks clean and clear and there doesn't seem to be any issue, if the TDS comes through at 0 I figure I'll be good ?

[RR37]

Anyone ?

[neanderthalman]

You'll be fine.

 

Had you drained the water, you'd be replacing the filters and membrane. You left it full, and so everything will be as it was.

 

I'd recommend discarding the first jug of water as a sensible precaution, but even that is likely unnecessary.

[AZDesertRat]

You will NOT be fine!

You will want to replace the prefilter and carbon due to potential bacterial growth and disinfect the system before installing the new filters. If the membrane stayed wet its possible its still good but a TDS meter will tell, same with the DI but I imagine its shot since it only has a 6 month shelf life to begin with once opened.

[RR37]

Hrm,

 

Well, I ran it last night. Filled a 5 gallon bucket tested the water and its all as it should be. IE as Far as I can tell its H20 TDS is @ 0. If there was something out of whack I am assuming the TDS would represent that no ?

[AZDesertRat]

A TDS meter will not detect bacteria or viruses. When the unit is sitting dormant the carbon has removed all traces of residual disinfectant and anything present in the water has a chance to grow and multiply.

Contact any reputable RO vendor and they will echo what I have told you. most will tell you to run the unit at least once every 7-10 days to keep it fresh, if its longer than that take the membrane and DI resin out and store them in zip loc bags with a small amount of water in the back of the refrigerator to keep them fresh. Discard the other filters, disinfect and start with fresh filters.

[neanderthalman]

WTF?

 

Viruses cannot multiply without a host.

 

Bacteria are too large to pass through the RO membrane, and if they did, will be killed by the high-purity water. It will swell and burst their cell membranes.

 

This is high-school level biology stuff.

 

You can argue if you like AZ, but you'd better start making sense if you're going to convince me.

[violinist]

Wastewater consultant versus hairy, smiling creature.

 

This

 

Should

 

Be

 

Good

[neanderthalman]

Never said I couldn't be wrong about this - but he's gotta convince me first.

 

Grab the popcorn!

[AZDesertRat]

Bacteria and virus don't have to make it through the membrane, they can and do live in the prefilter and carbon housings and on the outside of the membrane. You might want to visit a few manufacturers sites if you want to argue. I personally on more than one occasion have witnessed people sick and in two cases hospitalized from drinking water from unserviced RO units, its not a pretty site. I personally collected bacteria samples from one unit and delived them to the lab, again personally and backed up with a chain of custody form, just so you can't argue the point, and the results were amazing. The bacteria colony counts were too high to count and even higher than they wanted to estimate with any certainty, it was pointless to do a count anyway since they were that high.

 

The point is bacteria and viruses can and do live inside RO and RO/DI units that do not receive proper maintenance. If you have never taken a membrane fouled with slime bacteria out of a housing, its a real treat and stinks like the dickens.

[neanderthalman]

If the bacteria and viruses cannot get past the membrane, then how do they get into the drinking water?

 

I make no argument that bacteria cannot grow on the dirty side of the membrane - ie: the prefilters and carbon. How do then they get into the drinking water on the clean side of the membrane?

 

Is it only possible with a damaged membrane? Can the disuse cause this damage?

 

I'm trying to help you form a cogent argument to convince me, Just do your part. Explain how it all happens, step by step. How does the clean side of the membrane become contaminated with bacteria from the carbon and prefilters?

[AZDesertRat]

When a unit sits dormant water migrates from one side of the membrane to the other, TDS creep is the common term. You will also find many times the membrane ruptures or tears and passes solids on. If you don't use the TDS meter on a regular basis your only indication would be shortened DI life. Use the TDS meter at all points, tap, RO only and RO/DI to get used to what the readings should be. If something changes significantly stop using the filter until you can pinpoint the problem. When you cahnge the filters, disinfect the system, it takes about 5 minutes and can be very very important.

 

I have cut membranes apart and unwound the fabric to find them completely fouled with ugly red slime in some cases and still producing water. I have also seen membranes that were not set up properly with the 4:1 waste ratio and its like they are coated in table salt, the crystals fall off it just like salt when its dry. Proper setup and periodic maintenance are a must with any wate rtreatment device, that includes faucet filters, distillation units, RO systems, UV lights and anything else out there, nothing is 100% plug and play.

[neanderthalman]

Yes. I am familiar with TDS creep - but how does something as large as a bacterium manage to cross the membrane in any significant quantities without the membrane having been damaged. That's what I'm not understanding. If the TDS on the output indicates that the membrane is undamaged, how can the water be contaminated?

 

+1 to constant monitoring of TDS. Most people don't even flush their membrane.

[AZDesertRat]

When the osmotic pressure is the same on both side of the membrane it allows many things to pass, I don't know whay but it does. It does not take much bacteria to start multiplying in a nice warm filter housing with the chlorine removed and litle water movement. It can get downright disgusting in fact. I wish I had pictures of some of them.

[neanderthalman]

My understanding is that the membrane always allows the various ions to pass. The difference is in the rate at which they can pass the membrane - contaminants pass the membrane orders of magnitude more slowly. Compared with water, the rate is zero for all intents and purposes. When the unit sits, the water pressure equalizes almost instantly, but the ions continue to creep across at a snails pace. Eventually they too reach equilibrium, but much, much more slowly than the water.

 

What's bugging me is that the pores needed to slow/stop something the size of an ion will be on the order of nanometers/angstroms. However, bacteria are on the order of a few micrometers. They're a thousand times larger.....

 

Charge may play a role....

[AZDesertRat]

I can't answer you but maybe if this was moved to the Spectrapure Sponsors Forum we could get the President of the company to step in, he is a microbiologist or chemist by profession and could answer for us.

 

I do know when we first started designing and operating membrane systems in Arizona the state health officials would not allow us to consider the membarne as 3 log removal or an absolute barrier without almost a year of running two systems in series and thousands of dollars in testing and reporting. It was a painful process all because of cryptosporidium and giardia concerns. We were finally able to get them to buy off but it was a long process.

 

https://www.dow.com/liquidseps/prod/mfs.htm

 

Some things approach the atomic level while others are quite large in comparison.

[azzah]

They bypass the membrane through imperfect o-ringing. The water getting through isn't generally enough to upset readings (less than a mL per ML where I work) but is plenty for a few motile CFU's to get through.

Slightly old membranes are a new problem, once imperfections start forming microbial load goes up more than 100 fold while retaining <5 TDS. Bacteria can and certainly do get through RO units, potable water plants and home units are generally fitted with UV as the final stage...

[neanderthalman]

I can accept that answer.

 

 

Will it have any adverse effect on an aquarium or is it merely a bad idea to drink it?

 

[AZDesertRat]

I would say both. Higher and lower life forms can share the same diseases. I am mostly concerned about human life since water treatment is what I do but at home its for my critters too.

[azzah]

If you aren't drinking it it is no problem. Salt water tends to pose a slight osmotic problem for freshwater/airborne bacteria

[jm82792]

Interesting!

I enjoyed reading this.

[Rick Shaw]

USA pwned Canada

[RR37]

Jebus, last time I start a thread and then head out of town.

[Arctangent]

Great thread. Some knowledgeable comments. O-ring...doh!