Volatile Organic Chemicals | Drinking Water Compliance Assistance

What to Do If There's an Exceedance

Volatile Organic Chemical (VOC) Detects
If any VOC analyte(s) is/are greater than or equal to the reporting limit (0.0005 mg/L;
0.0015 mg/L for total xylenes), then the water system must:

  • Begin quarterly monitoring in the next quarter at that entry point to the distribution system (EPDS) for the entire VOC group
  • Continue quarterly monitoring until groundwater systems have achieved at least two consecutive quarters — four quarters if the maximum contaminant level (MCL)  is exceeded — with monitoring results below the MCL (this can include the quarter in which the initial detection occurred)
  • Submit at least four consecutive quarters (this can include the quarter in which the initial detection occurred) of results below the MCL (surface water systems)

Water systems with results that exceed the MCL must:

  • Increase to quarterly monitoring for a minimum of four quarters
  • Issue a Tier 2 public notice each quarter within 30 days of receiving the results from the lab 

After determining the system is reliably and consistently below the maximum contaminant level, ADEQ may allow the system to monitor annually. Systems that monitor annually must monitor during the quarter that previously yielded the highest analytical result.