Section 465

Section 465.360 Methodology

A laboratory must be certified for all analytical methods listed below that it uses. At a minimum, the laboratory must be certified for one total coliform method; one fecal coliform or E. coli method; and the pour plate method for heterotrophic bacteria.

a) The following methodology, as specified in the listed references, shall be followed for individual parameters:

Method References

Type of water	Parameter	Methodology	Reference [a]

Potable	Total Coliforms	Standard total coliform MTF & PA tests [b]	a

Potable	Total Coliforms	Standard total coliform membrane filter procedure	a

Potable	Fecal Coliforms	EC verification	a

Potable or Non-potable	Fecal Coliforms	Fecal coliform MTF procedure	a

Non-potable	Fecal Coliforms	Fecal coliform membrane filter procedure	a

Potable and Non-potable	Baterial Total Count	Heterotrophic plate count	a

Potable and Non-potable	Total fecal Coliform and E. coli	ONPG-MUG	a & c

Potable and Non-potable	Total fecal Coliform and E. coli	Colisure	See Appendix A

NOTES:

a. "Standard Methods for the Examination of Water and Wastewater."

b. Excluding the gram-stain technique.

c. "Manual for the Certification of Laboratories Analyzing Drinking Water," USEPA 570/9-90/008A, 4^th Edition (March 1997). A copy of this manual can be obtained by contacting the U.S. Environmental Protection Agency, Washington, D.C. 20465. This manual as published and dated is exclusive of subsequent amendments or editions.

b) The membrane filter procedure is preferred for the analysis of potable waters, because it permits analysis of large sample volumes in reduced analysis time. The membranes should show good colony development over the entire surface. The golden green metallic sheen colonies should be counted and recorded as the coliform density per 100 ml of water sample.

c) The following requirements for reporting any problems with public water supply sample results shall be observed:

1) Invalidate all samples resulting in confluent growth or TNTC (too numerous to count). Record as "confluent growth" or "TNTC" and request an additional sample from the same sampling site. Confluent growth is defined as a continuous bacterial growth, without evidence of total coliforms, covering the entire membrane filter. TNTC is defined as greater than 200 colonies on the membrane filter in the absence of detectable coliforms. A sample shall not be invalidated when the membrane filter contains at least one total coliform colony.

2) A laboratory that has elected to use the MTF or PA procedures must invalidate samples that produce turbid cultures in the absence of gas production (MTF) or an acid reaction (PA). A sample shall not be invalidated if coliform is indicated.