The Great Lakes Water Authority (GLWA) (Detroit, Michigan, USA) announced that it is in the process of increasing levels for the anticorrosion additive orthophosphate, which it feeds into water produced by its five water treatment plants in southeast Michigan.
Between October 2024 and February 2025, GLWA is slowly increasing the dosage of orthophosphate from 1.2 mg/L to 2.4 mg/L.
Orthophosphate as ‘Water’s Bodyguard’
Orthophosphate acts as “water’s bodyguard,” according to GLWA, by forming a protective layer within pipes to prevent metals such as lead, iron, and copper from dissolving in the water.
Since 1996, GLWA has added orthophosphate into its water to control both corrosion and its effects on water quality. Since that time, optimal corrosion control has consistently been maintained in the water delivered by GLWA and monitored in accordance with regulatory requirements of the Michigan Department of Environment, Great Lakes, and Energy (EGLE).
“While there is no lead in GLWA’s water and no lead pipes are used in the regional transmission system, upping the orthophosphate dosage will provide increased protections and assist our member partners in maintaining compliance with the changing lead action levels set by EGLE and updates to the U.S. Environmental Protection Agency’s Federal Lead and Copper Rule (LCR),” says Cheryl Porter, GLWA’s chief operating officer for water and field services.
Lead Action Level changes
Michigan’s action level for lead in drinking water is set to decrease from 15 parts per billion to 12 parts per billion on January 1, 2025. In 2027, a host of changes will also go into effect with the federal LCR, including a decrease in the time that municipalities have to remove lead service lines and a new trigger level for additional testing.
“GLWA’s processes and infrastructure must evolve alongside scientific advancements and technological improvements,” Porter says.
“Proactive efforts like these enhanced corrosion control measures underscore our commitment to protecting public health and ensuring our region’s water quality remains of unquestionable quality,” she adds.
Multi-Year Research Study
The change to GLWA’s corrosion control strategy was informed by a proactive, multi-year study conducted as part of a process of continual improvement and regulatory compliance.
As a part of the study, done in partnership with nationally known engineering firm Arcadis, specialty pipe loop rigs were constructed using pipes harvested from several local systems and installed at 10 testing sites.
One was placed at each of the five GLWA water treatment plants, while five were positioned at other locations within the member partner’s local distribution systems. Each member partner site represented a single water treatment plant’s water distribution service area.
During the study, tests were performed using variable amounts of anticorrosion chemicals to determine the most effective dosage recommendation.
The water will remain safe for consumption, as well as for household and business use, while GLWA implements the changes to its corrosion control strategy. Due to the increase in orthophosphate in the water treatment process, there will be an increase in the amount of phosphate that GLWA must remove during the wastewater treatment process.
GLWA says it remains committed to ensuring that it meets the goals of federal and state regulators to reach a 40% reduction in phosphorus. In 2019, it was the first treatment facility along the tributary to Lake Erie to achieve this milestone, according to GLWA.
Source: GLWA, www.glwater.org.