Water testing for fecal flora contamination is done in our laboratory, but there we receive water samples infrequently, sometimes in 3 months, sometimes once in a year.
Is there any guidelines for frequency or time duration between sampling for water microbiology?
You have asked a question that is compounded. You are interested in both frequency or time duration between sampling and analysis. A straightforward answer to your question may be inadequate. I choose to break it into two. Frequency of sampling for microbiol analysis should be determined by the source of the water and its mode of supply. For example if the source is a dug well with or without a windlass, it is desirable that the sampling to ascertain the water maintains its microbiol quality/suitability for human use, then such sources must be tested at least once every two months, which is 6 times per year. If it is a borehole or dug well with a hand pump, such a water source should be sampled at least 4 times per year. Gravity spring, piped supply groundwater, and wells whether piped or not should also be sampled at least 4 times per year. Treated surface that has been chlorinated and serving a sizable population, should be sampled for examination one per month. Hence you can see that both source and mode of supply are factors in determining the frequency of sampling for analysis.
Relating to time between sampling and analysis, it is desirable that the analysis is undertaken within 24 hours. Having given this time span, I would wish that the duration between sampling and analysis, shall be influenced by other factors including storage mechanisms where cooling of such samples is paramount. In any case, planning for sampling frequency, and analysis time frame should be part of the routine in meaningful work. Where you have no control over these, the results of analysis may only be academic, and not necessarily serving the purpose of human health protection.
Further literature on the question can be obtained from among other sources the World Health Organization Guidelines for drinking water quality. My little input for your question....
Thank you Dr Saeed.
Can you please tell me the source of information you shared with me?
I mean the guidelines where this information is taken from.
Please refer to WHO Guidelines for drinking water quality 2nd Edition Volume 3: Surveillance and control of community water supplies, published by A.I.T.B.S Publishers & Distributors, Delhi.