RO machines have a divert system where it will divert to drain for a period of time before going to your holding tank. I don't have one but I think the criteria is conductivity. The output of the RO will go to the holding tank once the conductivity is low enough.

Question: Will this initial flush keep you bacteria free going to your holding tank? Anyone test this? I think the answer's no because the RO has set long enough for small amount of bacteria to develop. Once there a rinse is not enough to rid. What do you think?
Thanks

Lefty,

Let's start our with this...

In my clinic (Texas), we MUST have a diversion valve via RO. [RD:52/62]:

"...[should] include a means to prevent patient exposure to unsafe water, such as diversion of product water to drain..."
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***Keep in mind***
"..in the absence of an automatic divert to drain valve for an RO, the staff must demonstrate knowledge of the requirement to manually stop water flow to the dialysis machines/related equipment..."
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As for bacteria, you will always have it. No matter what. If you do your monthly, or biweekly systemic disinfection(s) and your cultures/endotoxins are good, then you are not to worry.

Just make sure your clinic is in compliance by reviewing your state regulations. You should choose the most strict regulation.

I hope this helps.

Lefty,

The divert to drain depends on TDS. TDS and bacteria are two separate things. You can have very low TDS with very high Bacteria. Total disolved solids(TDS) is a measurment to track the performance of the RO and has nothing to do with the bacteriological content of your water. Your monthly cultures of the water will tell you how well your disinfection schedule is working.

Most RO manufactures recommend quarterly membrane cleaning/disinfections, this can include dwelling disinfectent in the permeate piping. Furthermore, Post Holding tank ultrafiltration is recommended.

HiloTech has it right...bacteria does not contribute to conductivity. Plus, the divert to drain diverts the RO product water to drain; the bacteria is mostly on the raw water side. Many ROs will have a flush feature that you can program to flush the raw water side (concentrate flow increases) to drain. Or, you can open a manual valve to increase the concentrate flow periodically. Maximizing this flush can REDUCE bacteria on the raw water side of the membrane. You will never be bacteria free!

As an interesting side note, If you have a system installed by GE or the GE guys with MarCor they will drill and tap a Banjo connection right into the Sch40 drain line and attach the drain hoses right to it, including the divert to drain line. I have, in the past, seen on several occasions, bacterial contamination from this line. I know it sounds a little far fetched but what happened is bacteria from the large open drain line grew up the hose and contaminated the divert valve itself. If you cut that hose and attach some fittings (3x1 reducer bushing with pipe nipple, adaptor and hose barb)to the wall to make a "free flow air gap" it will solve the re--occuring contaminations. Have done this 4 times and worked every time.

John

Nashville

Sidenote, Do you disinfect the divert to drain path when you do your loop? We divert the 1:100 bleach to drain to try and disinfect the divert path.