Water Quality Question

[PurewaterGuy]

Anyone knowledgeable about Gram Negative Bacteria? I recently had some tap samples sent to a lab and they came back positive for Gram Negative Bacteria. Standard plate count testing done, results in 48 hours. Is this harmful for human consumption?

 

[cvg]

not generally a good bacteria to have in your water supply...

http://en.wikipedia.org/wiki/Gram-negative

 

[bimr]

Potable water should not contain bacteria. Bacteria is a contamination and any contamination may be harmful. Suggest you flush and chlorinate.

http://en.wikipedia.org/wiki/Gram-negative_bacteria

Legionella is an example of a small gram-negative rodshaped bacteria.

http://www.epa.gov/waterscience/criteria/humanhealth/microbial/legionellafs.pdf

 

[GarySCWSVI]

You need to have whoever tested the water to identify which "Gram Negative Bacteria" is present. Just saying Gram Negative Bacteria is way too general. It encompasses a whole lot of bugs. Some good for us. Some bad for us.

Gary Schreiber, CWS VI
The Purolite Co.

 

[quark]

Potable water limit for bacteria is 500cfu/ml. I agree with Gary. You should get the typing done and see whether the bacteria is really dangerous. Gram staining is a preliminary method of identification and the story starts there.

 

[PurewaterGuy]

"Legionella is an example of a small gram-negative rodshaped bacteria."

Interesting.

My report that came back states 80 CFU/ML -
Gram Negative Rods

Does this tell me anything?

However, a couple of them came back as "too numerous to count"

Also been reading Reverse Osmosis is not a good source for Gram Negative Bacteria removal.

Thoughts on this?

Thanks

 

[PurewaterGuy]

Question. Is a 0.05 Hollow Fiber Ultrafilter enough to remove all gram negative rods?

Does anyone know what the micron rating for a Diasafe Plus Ultrafilter is?

 

[GarySCWSVI]

Most membrane manufacturer's and supplier's that I know disclaim using membrane (RO, UF, NF, MF) for bacteria removal. Bacteria can grow thru the membranes.

I agree with the previous statement by Purewater guy:
"Also been reading Reverse Osmosis is not a good source for Gram Negative Bacteria removal."

Gary Schreiber, CWS VI
The Purolite Co.

 

[PurewaterGuy]

I've been in this business long enough to know proper pretreatment to RO is essential. Not only that but the RO should run very frequently to keep the membranes cleaner to prevent fouling. An idle RO is not a good thing on many levels. This particular RO is meeting and in some cases exceeding AAMI Standards.

Current problem involves the current setup. 20" 5 micron Hytrex filter, followed by 2 Carbon units containing 1.2cft of Acid washed carbon each, followed by 2 units containing 1.2cft Mixed-bed resin each, followed by a 20" absolute rated 0.2 Filter, followed by a 20" 0.05 Ultrafilter. There is absolutely NO WAY I should be having any breakthrough at all. (I have also replace all the black 5/8" PE tubing connecting each component)

Looking for any and all input here. Theories, possible solutions, tried and true,,,

Spoke to Fresenius Technical Support about the Diasafe Plus Ultrafilter on their 2008K models, no luck there, they have to contact the German manufacturer, you would think if they have the ultrafilter on the machine they would at the very least know what the cutoff would be for micron rating ,,,,

I figured if the machine cultures are NOT coming up with gram negative rods then i should be able to mirror the micron rating prior to the machine thereby eliminating the possibility of any problem with gram negative rods ,,

Make sense?

Input much appreciated.