I am looking for a statistical amounts which are allowed.
Some students say it is 0 for all bacteria, which I think is false.
I found [this USA source][1].


I found there

- Total Coliforms (including fecal coliform and E. Coli) mg/l. No more than 5.0% samples total coliform-positive (TC-positive) in a month.
- Giardia lamblia: 99.9% removal/inactivation.


**What is the right place to look for such information?**


  [1]: http://water.epa.gov/drink/contaminants/