DDW To Revise DLRs

On November 3, 2022, at 9:30 am, the State Water Resources Control Board (SWRCB), Division of Drinking Water (DDW) will hold a public workshop on proposed revisions to the detection limits for purposes of reporting (DLR) for eight metals, and new DLRs for three constituents with secondary MCLs. The formal regulatory process to propose and finalize these changes, has not yet begun. Public comments are due by noon, November 18, 2022.

The workshop will be held via remote video software only. Link to view the November 3, 2022 workshop:

DDW is proposing to make the changes in a two phase program. Phase I would lower the lead and nickel DLRs and establish DLRs for iron, manganese, and zinc. Phase II would lower the DLRs for antimony, arsenic, beryllium, cadmium, lead, manganese, mercury, and thallium with a three-year compliance schedule.

The DDW announcement includes the following statement about an additional change: “Revisions to the lead and copper reduced monitoring frequency and large water system corrosion control treatment study criteria such that the criteria are not dependent on the lead DLR or federal lead method detection limit.”

The table below presents the current and DDW’s proposed DLRs.

Table: Current and Proposed Metal DLRs
Proposed DLR
Contaminant PHG (mg/L) MCL (mg/L) Current DLR (mg/L) Phase I Phase II
Antimony 0.001 0.006 0.006 No change 0.001
Arsenic 0.000004 0.010 0.002 No change 0.0005
Beryllium 0.001 0.004 0.001 No change 0.0005
Cadmium 0.00004 0.005 0.001 No change 0.0005
Iron None 0.3 None 0.10 No change
Lead 0.0002 0.015 0.005 0.001 0.0005
Manganese None 0.05 None 0.020 0.010
Mercury 0.0012 0.002 0.001 No change 0.0002
Nickel 0.012 0.1 0.01 0.005 No change
Thallium 0.0001 0.002 0.001 No change 0.0008
Zinc None 5.0 None 0.050 No change

There is no indication of a timeframe when the formal rulemaking would begin.