Characteristics of Good Indicator Organisms?

[Entropy]

I need to determine why good indicator organisms are present in low numbers - <1% of the total population. I've tried researching, but most websites discuss why indicator organisms should be present in high concentrations (relative to pathogenic bacteria). Why do they need to be present in such low numbers? Is it related to sensitivity? Thanks so much in advance.

[choozi]

As far as i know, Indicator organisms are itself non-pathogenic. It should be greater in number as compared to Pathogens (in fecal sample) so that you could easily determine whether your water sample is fecal contaminated or not. To detect either water is potable or fit for drinking, you tried to find the indicator organism in your water sample. If the number of indicator organism is extremely low. It shows your water is fit for drinking.