Table 1: Microbial Monitoring under GWDR: possible indicators

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Table 1: Microbial Monitoring under GWDR: possible indicators

Organism	Density in raw sewage	Occurrence in human stools	Survival in environment	Lab Availability	Association with fresh fecal contamination
Bacterial indicators
total coliforms	>10⁹/L	100%	Weeks to years	Excellent	Indirect
E. coli	10⁹/L	100%	Weeks to months	Excellent	Good
Enterococci	10⁷/L	100%	Weeks to months	Excellent	Good
Clostridium perfringens spores	10⁶/L	100%	Months to years	Potential good	Fair
Viral indicators
Somatic coliphage¹	10⁶/L	50%	Weeks to months	Potential good	Good?
Male-specific coliphage¹	10⁶/L	<5%	Weeks	Potential good	Good
Viral pathogens
Enteroviruses by PCR²	50-250+ PFU/L in U.S.	---	Weeks to months	Potential fair	Good

¹Coliphage are viruses that infect the bacterium, E. coli.

²Enteroviruses include polioviruses, coxsackieviruses, and echoviruses. PCR (polymerase chain reaction) is a process to multiply the number of a specific DNA or RNA strands, allowing easier detection by a variety of methods. PCR must be combined with other processes, such as sample filtration, filter elution, sample purification, perhaps tissue cultures, and assay procedures (e.g., genetic probes).

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