Hello Sir/Madam,
There is no manual or publication or guidelines which talks about following a particular drinking water testing regime for e.g for bacteriological test the CPHEEO manual suggests the sample should be taken according to population size, but it does not suggest anything about how many samples should be taken for residual chlorine test or samples for physical/chemical test and how often.
I would like to know if there is any method of sampling for testing or guideline for any testing regime which would ensure a city/town/village safe drinking water.