401 KAR 8:250.  Inorganic chemical sampling, analytical techniques and maximum contaminant levels.

The system shall collect one sample per entry point to the distribution system or representative site of each source at initiation of water system operation.  Thereafter, the system shall collect one sample during the first three-year compliance period of each nine-year compliance cycle, i.e. 2002-2004, 2011-2013, etc.  If a sample exceeds 0.5 mg/L, the system shall initiate quarterly monitoring.  A system shall sample for a minimum of four consecutive quarters with results less than the maximum contaminant level (MCL).  Afterwards, with Drinking Water Branch approval, the system shall sample annually during highest "historical" quarter.  If a sample exceeds the MCL, the system shall collect a confirmation sample within 24 hours or immediately notify the public.  A confirmation sample collected within two weeks at the same sampling point as an MCL exceedance may be averaged with the first sample to determine compliance.

Technical fact sheet from EPA for nitrite.