Coliform Enumeration in Potable Water, Dairy Water, Bottled Water and Vending Water Samples
PHL Location |
Central Laboratory, Amite Laboratory, Lake Charles Laboratory and Shreveport Laboratory |
CPT Code |
N/A |
Synonyms |
MTT, Multiple Tube Fermentation 10-tube Most Probable Number (MPN) Technique for the Detection and Quantitation of Total and Fecal Coliforms in Potable Water. |
Brief Description of Test |
This method detects and estimates the total coliform population and the fecal coliform population in water samples through the use of sample inoculations into replicate tubes of selective media incubated under varying, well-defined conditions. |
Possible Results |
Total coliform & E. coli MPN/100 ml |
Reference Range |
<1.1/100 ml |
Specimen Type |
Potable water, Dairy Water (all types, including recirculated cooling water and glycol water), bottled water, vending water. |
Specimen Container(s): |
Sterile, disposable 100 ml Nasco Whirl-Pak bag containing a 10 mg sodium thiosulfate tablet; Bottled water-submitted in commercial packaging. |
Minimum volume accepted: |
100 ml |
Collection Instructions |
Collect representative sample according to established protocols. When using the Whirl-Pak bag fill to 100 ml line and leave at least 1 inch of air space at the top of container. Whirl bag to close. Do not twist tabs together. |
Storage and Transport Instructions |
Store refrigerated & transport sample(s) in clean cooler(s) with ice packs (ice is not recommended due to melting and possible cross contamination). Submitters are encouraged to hold drinking water samples at <10ºC during transit. Dairy water samples must be 0 – 4.4ºC upon receipt in laboratory. Maximum holding time is 30 hours. Bottled water need not be refrigerated or cooled, and has no maximum holding time. |
Causes for Rejection |
Sample > 30 hours old; sample frozen, no sample ID, unacceptable collection container, insufficient sample, sample leakage, incomplete sample form, or sample totally immersed in ice-water. |
Limitations of the Procedure |
Improper mixing of sample will allow for underestimating of the bacteria density of the sample. |
Interfering Substances |
Excessive chlorine and heterotrophic levels. |
References |
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Additional Information |
Complete a Lab 8 Laboratory Request and Report Form. The following is required Lab 8 information: Sample sequence #’s and project code, name of supply, collected by (name or initials), PWS ID (if applicable), date and time of collection, type of sample and disinfectant residual (if applicable). |