What is Considered Optimized Corrosion Control?

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What is Considered Optimized Corrosion Control?
The Lead and Copper Rule (LCR) is the only regulation that requires “opti­miza­tion,” which means that even if a system meets the lead action level consis­tently, if the state or EPA believe the treatment is not “optimized,” states can require further studies for treatment opti­miza­tion and modi­fi­ca­tions. 

So what is considered “optimized corrosion control treatment”? 

All roads to optimized treatment in the Lead and Copper Rule Revisions (LCRR) go through the new sampling require­ments per 141.86 which are summarized in this tap sampling guidance page. If your system can prove your sampling pool and procedures do not change based on the LCRR, then you should be able to grandfather in your previous compliance sampling round.

However, if your sampling pool or procedures needs to be modified to meet the require­ments of 141.86, then it is our under­stand­ing that your system will need to start from scratch and perform two 6 month monitoring periods with the new procedures. Based on the results of those two monitoring periods, a system is considered to have optimized treatment if it meets one of the following: 

1. A small or medium-sized system without corrosion control treatment is considered to have optimal corrosion control if it does not exceed the lead action level (15 μg/L) and copper action level (1.3 mg/L) during two (2) consecutive 6 month tap sampling monitoring periods. Thereafter, the system must remain at or below the lead trigger level (10 μg/L) and copper action level (1.3 mg/L) in all tap sampling periods conducted in the future.

2. A small or medium-sized system with corrosion control treatment is considered to have optimal corrosion control if it does not exceed the lead trigger level (10 μg/L) and copper action level (1.3 mg/L) during two (2) consecutive 6 month tap sampling monitoring periods. Thereafter, the system must remain at or below the lead trigger level (10 μg/L) and copper action level (1.3 mg/L) in all tap sampling periods conducted in the future.

3. Any water system (including large systems) with the 90th percentile tap water lead level less than or equal to 5 μg/L (practical quan­ti­ta­tion limit) and does not exceed the copper action level (1.3 mg/L) during two (2) consecutive 6 month tap sampling monitoring periods.

4. A small or medium-sized system with corrosion control treatment that exceeds the lead trigger level (10 μg/L) but does not exceed the lead or copper action levels during two (2) consecutive 6 month tap sampling monitoring periods, performs the re-opti­miza­tion corrosion control treatment study require­ments per the Rule, and thereafter remains at or below the lead and copper action levels in all tap sampling periods conducted in the future. This system would be considered to have re-optimized optimal corrosion control treatment even if the 90th percentile continues to exceed the lead trigger level. 

5. Any system (including large systems) that has implemented the corrosion control treatment study steps for re-optimized corrosion control treatment and remains below the lead (15 μg/L) and copper (1.3 mg/L) action levels on subsequent sampling unless the state requires additional studies.  


Tap Samples after OCCT

As stated above, to qualify for the above categories for “optimal corrosion control treatment,” most systems will need to initially start with two (2) rounds of 6 month sampling meeting the new sampling require­ments in Section 141.86.

After that, any system deemed to have optimized corrosion control treatment shall continue monitoring for lead and copper at the tap no less frequently than once every three (3) years using the reduced number of sampling sites. Your state may require more frequent sampling.

Any system collecting lead tap samples annually or less frequently, must collect the tap samples during the months of June, July, August and September unless otherwise approved by the state.


Water Quality Parameters (WQPs) after OCCT

Any system that installs or modifies CCT is required to monitor water quality parameters (WQPs) based on the following:

  • 6 month monitoring periods
  • Samples must be collected throughout the monitoring periods to reflect seasonal variability.
  • Two (2) samples each monitoring period at each WQP site
  • One (1) sample at each entry point to the distri­b­u­tion system, every 2 weeks

After your system is designated to have OCCT, the state will specify the optimal WQP values reflecting OCCT based on the results from the WQP monitoring discussed above. Continue with 6 month monitoring periods at the standard WQP sites, plus the find-and-fix WQP sites, until the state approves otherwise.

The following scenarios will allow systems to perform reduced WQP monitoring unless otherwise required by their state: 

  • Any large system maintaining water quality within the designated optimal WQP ranges and does not exceed the lead trigger level (10 μg/L) during two consecutive 6 month monitoring periods:
    • Continue sampling at entry points to the distri­b­u­tion system once every 2 weeks
    • Two (2) samples at reduced number of WQP sites, plus find-and-fix WQP sites, every 6 months 
  • Any water system that maintains water quality within the designated optimal WQP ranges and does not exceed 5 μg/L for lead or 0.65 mg/L for copper at the 90th percentile of tap samples for two consecutive 6 month monitoring periods:
    • Continue sampling at entry points to the distri­b­u­tion system once every 2 weeks
    • Reduce sampling from every 6 months to two (2) samples annually at the reduced number of WQP sites, plus find-and-fix WQP sites
  • Any water system that maintains water quality within the designated optimal WQP ranges and does not exceed the lead trigger level (10 μg/L) or copper action level (1.3 mg/L) during three consecutive years of monitoring:
    • Continue sampling at entry points to the distri­b­u­tion system once every 2 weeks
    • Reduce sampling from every 6 months to two (2) samples annually at the reduced number of WQP sites, plus find-and-fix WQP sites

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https://www.epa.gov/ground-water-and-drinking-water/review-national-primary-drinking-water-regulation-lead-and-copper
On December 16, 2021, EPA announced the current Lead and Copper Rule Revisions (LCRR) will go into effect to support near-term actions of reducing lead in drinking water. At the same time, the agency is developing the Lead and Copper Rule Improvements (LCRI) to strengthen key elements of the rule which will be finalized by the original October 16, 2024 compliance date. 
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