Performance in corrosion control programs should be measured — not assumed.
Municipal utilities across the United States rely on documented data when evaluating strategies to reduce metal release and support compliance with the EPA’s Lead and Copper Rule (LCR). As infrastructure modernization continues nationwide, treatment optimization remains an important component of comprehensive water quality management.
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Phosphate-based corrosion inhibitors have been used for decades in distribution systems to reduce corrosion rates and minimize lead and copper release. When properly implemented and monitored, municipal case studies demonstrate measurable, verifiable reductions in both corrosion rates and finished water lead concentrations.
Below are documented results from full-scale municipal systems utilizing Carus phosphate solutions.
Corrosion Control as a Measurable Strategy
Carus offers a portfolio of orthophosphate, zinc orthophosphate, and blended phosphate solutions designed to address varying water chemistries and system conditions.
Learn more about our full Corrosion Control Solutions.
Field data from municipal applications show that corrosion control performance can be quantified through measurable improvements in corrosion rates, lead concentrations, and overall distribution system stability.
Case Study: CARUS™ 8600 Blended Phosphate
In a municipal system evaluating corrosion performance, CARUS™ 8600 Blended Phosphate was compared to phosphoric acid at equal total phosphate dosing (1.0 mg/L).
Documented results included:
- Lead corrosion rate decreased from 0.26 mpy to 0.07 mpy
- Copper corrosion rate decreased from 0.53 mpy to 0.26 mpy
- Mild steel corrosion rate improved from 4.20 mpy to 3.33 mpy
- Distribution system lead concentrations declined from 27 ppb to 5 ppb within one year
These results reflect measurable reductions in both corrosion rate and lead release under full-scale municipal implementation.
Case Study: CARUS™ 8650 Blended Phosphate
A separate municipal utility experiencing first-draw lead levels as high as 50 ppb implemented CARUS™ 8650 Blended Phosphate as part of its corrosion control strategy.
Documented performance included:
- After 1 year: Highest lead levels reduced to 18 ppb, with designated compliance sampling locations measuring 2 ppb
- After 2 years: Highest lead levels further reduced to 12 ppb, with monitored compliance sampling locations maintaining 2 ppb
- Up to 90% reduction in lead concentrations at targeted compliance sampling locations
- Qualification for reduced lead monitoring frequency
These results demonstrate sustained, multi-year reductions in lead concentrations at monitored compliance sampling locations within the distribution system.
Case History: CARUS™ 8500
In a Midwestern system facing elevated lead levels and extended hydrant flushing times, CARUS™ 8500 was implemented as part of a corrosion control optimization program.
Measured outcomes included:
- All first-draw lead samples below 15 ppb within 60 days
- After one year, lead levels measured below 7.5 ppb
- Hydrant flushing time reduced from greater than 30 minutes to less than 5 minutes
- Reduced customer discoloration complaints
Beyond compliance metrics, these improvements reflect enhanced distribution system performance and operational stability.
Operational Performance Benefits
Corrosion control programs influence more than regulatory sampling results. Utilities have documented operational improvements associated with optimized phosphate treatment, including:
- Reduced chlorine demand
- Improved distribution system stability
- Decreased frequency of filter backwashing
Additional operational data can be found in the AQUA MAG® Case Study.
Phosphate Corrosion Control and the Lead & Copper Rule
Orthophosphate corrosion inhibitors are widely recognized within Lead and Copper Rule compliance strategies as a method for minimizing lead and copper release in drinking water systems.
For additional regulatory context, see:
Is Your Corrosion Control Strategy Ready for the Revised Lead and Copper Rule?
As utilities evaluate both infrastructure replacement and treatment optimization, corrosion control remains a measurable, verifiable component of comprehensive water quality management — supported by documented municipal performance data.