Presence Absence and MPN testing for Coliform Bacteria

An explanation of the Colilert method of "Presence / Absence" and "Most Probable Number" testing for coliform bacteria and e-coli bacteria.

[TheJessehart]

I'm in Minnesota and have passed my D, C and B water operators test using your math DVDs and watching your videos. I am taking my A test Thursday. I have done 3 Sacramento books and can honestly say that your information is so easy to understand. You are a very valuable person and teacher to the water community. I hope you continue to make videos as I feel I learn better this way. I truly appreciate all that you have done. PLEASE don't stop doing what you do. Thank you so much!

Jesse.

[arthercasillas]

Thank you. You bring great insight. You time is greatly appreciated.

[connorwilloughby]

Useful video. Should you be wearing gloves handling potentially pathogenic water samples and shouldn't the sample be opened under a Bunsen or in a fume cabinet to prevent contamination?

[trinaolin]

Thank you for all the informative videos! We have a rule at my district that we cannot take a coliform sample unless the free chlorine residual is above .20 mg/L. Since the bottles have sodium thiosulfate in them, does the free chlorine residual even matter? I had been taught one way but now I'm starting to wonder.

Thanks again for all you do! Your videos are so helpful and easy to understand

[armandomorales]

Very interesting video,  we in Mexico i´m working on WWTP but cannot find tech as you have

[pigwillnot]

u made that easy !! i actually get it now thanx water sifu

[Amy.Nz_]

Thank you! this video is very helpful! :)

[sithlordmaster]

Do you think there is a 4 hour window?

[omarxawneh]

no need for sample dilution :/ ? or is it because treated water?

[pluto]

Hello! May I ask for how long is the water sample still valid for testing for MPN after I collect it? Is it still valid if I store them in a sterile bottle for 12 hours or 24 hours? Thank you!

[yildizjaddil]

Under the uv, positive of ecoli will be in white and negative will stay yellow...correct? Abit confuse

[moha.salah]

Excuse me, can i working this method on wastewater ?!

[Jinebethp]

uhmm.. did i heard it right? you incubate it for 24 hours? is it too much ? the requirement for incubation is only 18 hours until 22 hours ...