hi

For drinking water this level not is acceptable at least for E.coli, however for batting waters for recreational purposes it can be a good tool.

best regards

Dear Marco,

This is depend on the type of water you going to evaluate, however, 100 CFU/ml is enough.

https://www.researchgate.net/publication/273449734_Water_Quality_Assessment_of_River_Nile_at_Rosetta_Branch_Impact_of_Drains_Discharge

Article Water Quality Assessment of River Nile at Rosetta Branch: Im...

This level is too high for drinking water and therefore, you should not use this CFU/ml

for drinking water you can use membrane technique, It detects 1 ufc/100mL or absence/presence technique in 100 mL for coliform/E. coli

About count of mesophilic aerobic bateria is less tan 10ufc/100mL in bottled drinking water

 If this is a preliminary determination then it is okay and that's too if the faecal contamination is high. For final determination you should go for more sensitive methods/kit.

Dear all, thanks for you kind contribution.

Dear Prof. Yuri Torres Kam, could you give some better indications regarding the membrane technique you wrote about, please?

You have to always keep in mind that the standard required is absence of faecal contamination in 100 ml. Any test not reaching that limit is as such useless. Secondly, there is no predictive power from total counts (or alike) to the size of a possible faecal population. If you really want to be sure of the faecal conatmination, the only option available is to measure exactly that population. The  most important reference to which method to comply to are the ISO standards.

Marco, Here is a link to some information regarding drinking water limits in the USA.  http://water.epa.gov/drink/contaminants/basicinformation/pathogens.cfm  These pertain to drinking water regulations which are very strict, and apply to water treatment facilities.  These are post treatment regulations, and not for source water, the limit is zero cfu.  It is called the total coliform rule -  see the link below for a list of approved analytical methods for drinking water compliance monitoring in the USA   http://www.epa.gov/ogwdw/methods/pdfs/methods/methods_tcr.pdf

Many labs use the colilert system which is listed as approved https://www.idexx.com/water/products/colilert.html

Dear all, thanks again for your answers.

The sensitivity is clearly not enough, even for a preliminary result. From your answers and contributions from other experts I spoke with, I also understood that the result is not representative of the situation, and we cannot get any clear indication.

It is much better to move towards the use of compact dry EC (type of MF) with a compact incubator: it not very expensive, and with some trainings results are much better. About the time required, we need 24 hours, but still the quality is on a different stage. If some is interested, this paper gives a good overview of water quality testing methodologies. http://www.hip.fhi360.org/file/28138/FactSheet%20on%20Microbiological%20Indicator%20Testing.pdf

Best regards,

Marco

Dear Marco Caniato, you can see:

http://www.merckmillipore.com/PE/es/products/industrial-microbiology/bioburden-testing/.leb.qB.xg8AAAE_M_B3.Lxi,nav

regards

Yuri

Hi Marco your kit will give you many positive false, it's recommendable acquire a qualitative coliform kit.

Hi Marco, Are you using general HPC bacteria as an indication of fecal pollution, or is there some indicator in the test (e.g. ONPG/MUG) that will tell you if coliforms or E. coli are present? In the U.S.,  HPC is not used as a health indicator--as you pointed out, they are typically considered harmless--but they are often used as an indicator of adequate disinfection and the maintenance of the water system. The USEPA limit is 500 cfu/mL, so it's possible that a sensitivity of 100 cfu/mL is adequate if you wanted to consider anything with

Dear Windy,

thanks for your interesting comment. Actually I wanted to use a easy-to-do and rapid test for having a proxy of contamination, applicable in ANY situation. Actually it is not sensitive enough, we cannot apply it to raw water, and even for testing disinfection level it is not enough, as we do not have always a actual disinfection (e.g. with filtration I do not think it can provide an adequate confidence).

I am quite interested in the Colilert 18 (the upgraded model for the European market): it has a better sensitivity, a good range of temperature (36+-2 °C), and it is faster. Quantitray is interesting as well, but it is more expensive, more complicated and bigger.

Actually I am not complitely satisfied by Colilert 18: it is cheap, we can use a cheap portable UV lamp, but incubators are expensive and not easy to carry and use in the lack of power. Some interesting models of incubators, like those made of change phase material (e.g. MIT PortaTherms http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3111905/ , used also by Bristol University and Oxfam Gb for AQUATEST http://www.bristol.ac.uk/engineering/research/water/research/aquatest.html).

However, I feel that there is still room for improving water testing technologies, in particular for constrained situations. It would be interesting to work on it!

Regards

Marco

Hello Marco,

From a practical point of view, the answer to this question depends in my opinion of the legislation. This legislation is often local (country, towns ...) but also depends on the use of water (drinking water, bathing water, etc.). Finally, I think that he answer depends on the use we want to do with this "norm".

Membrane Filtration Technique (MFT) (CFU/100ml) is one of the best and efficiency method to detected the microbial contamination in the drinking water (Total and Feacal coliform bacteria). Please find the following link, It’ll provide the better idea of the MFT. According the colour, you can easly separate the colonies of Total Coliform (Yellow) and Feacal Coliform (Green). I have checked more than 1000 samples of drinking water with this method. It’s always produced the better result and even I checked with the control as autoclaved water.

https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma-Aldrich/Datasheet/1/39734dat.pdf

Find my presentation in slideshare - Slide Number 11.

https://www.slideshare.net/AbinaiyanIlango/physicochemical-and-pathogenic-contamination-status-of-groundwater-in-kilinochchi-district-sri-lanka-82261365

Dear Marco,

Here is an extract from the Walloon legislation (a region of Belgium) concerning the bacterial standards of drinking water (tap water):

Units: #/100 ml

E. coli 0

enterococci 0

Dear Marco,

Measurement of Coliform Bacteria in Drinking Water.

Water samples for coliform bacteria must be collected in sterile bottles using specific procedures. The bacteria are then grown in a laboratory and quantified. There are three measurements of coliform bacteria:

Total coliforms. This measurement includes all coliform bacteria. These bacteria include many different species that live in different environments such as soil, water and vegetation, as well as in the intestines of warm-blooded animals. Most species of coliform bacteria are not harmful, but some coliform bacteria can cause mild or severe illness. The presence of coliform bacteria indicates a pathway for contamination of the water supply from the source of the bacteria (which could be a septic tank, sewer system, animal waste, runoff, etc.). This same pathway could potentially be taken by disease-causing organisms.

Fecal coliforms. These bacteria only include coliform bacteria that live in the intestines of warm-blooded animals, including humans. The presence of fecal coliform bacteria indicates possible contamination by human or animal waste.

coli. This is a specific species (full name Escherichia coli) of coliform bacteria. There are hundreds of different strains of E. coli, most of which are harmless to humans. However, several strains of E. coli are harmful and can result in severe illness. E. coli is specific to the intestines of humans and other organisms, so detection of E. coli indicates contamination of the water supply with human or animal waste.