City’s new corrosion control for drinking water starts in August under recent federal rule change
In August, the city is set to begin its new corrosion control enhanced water treatment technique in response to new rules from the Montana Department of Environmental Quality and the U.S. Environmental Protection Agency.
Residents shouldn’t notice any change to the taste or feel of the finished water, according to city staff, who told The Electric that the new corrosion control method is a common treatment technique used nationwide.
DEQ mandated the corrosion control meant to reduce the risk of lead exposure in drinking water, which can be caused by lead-containing service lines and interior plumbing materials, according to the city.
Homes and businesses that do not have lead service lines or lead interior plumbing have a low risk of lead exposure in drinking water.
Under city policy, property owners are responsible for ownership and maintenance of their service lines and interior plumbing.
The corrosion control process involves adjusting the chemistry of the finished drinking water by adding small amounts of sodium hydroxide and orthophosphate.
Sodium hydroxide, a common water treatment base, keeps the water’s pH at or above 7.20, reducing the water’s inherent corrosivity, according to city public works.
Orthophosphate, widely used across the water industry, forms a protective layer inside distribution components such as service lines and interior plumbing.
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At pH values below 7, water becomes more acidic, increasing its capacity to solubilize metals and other constituents from internal plumbing and service lines, according to the city.
Low pH water can accelerate the dissolution of metals such as lead, copper, and iron, especially in systems with low alkalinity or minimal existing protective scale.
Sodium hydroxide elevates water’s pH and supports the formation of more stable carbonate and hydroxide scales on internal pipe surfaces, further contributing to corrosion mitigation.
The sodium hydroxide works in conjunction with orthophosphate, which reacts with dissolved metal ions, promoting the formation of insoluble metal phosphate complexes.
Over time, the compounds form a thin, adherent, protective film on the interior surfaces of distribution components such as service lines, fixtures, and internal household plumbing.
This layer functions as a physical and chemical barrier between the water and the pipe materials, reducing the likelihood of metals dissolving into the drinking water, according to city public works.
In September 2025, City Commissioners approved a $945,000 contract to MJD Contracting, LLC for the project.
DEQ notified the city in August 2023 that its water treatment was no longer optimized for lead and copper corrosion under EPA’s recent rule change.
The city previously contracted with Morrison-Maierle to perform a corrosion control study. The firm recommended that the city implement a new chemical feed to increase the pH of the finished water at the Water Treatment Plant by utilizing a 50 percent caustic and an orthophosphate solution.
The treatment will also guard against pH and alkalinity fluctuations of raw water, and address concerns with high calcium and dissolved inorganic carbon in finished water, according to the city staff report.
The corrosion control project is one component of the new rules from the U.S. Environmental Protection Agency that city staff have been working on for several years.
City officials have said in multiple public meetings that the revision for stricter compliance was triggered by the 2014 Flint, Mich., water crisis, in which public water supplies were contaminated with lead.
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The changes include increased water testing and the city must identify the types of water pipes throughout the city.
City staff has been preparing for the federal changes and working on the inventory for several years.
The city posted the inventory of known lead, copper and galvanized water service lines, as well as those that were unknown, with their addresses, in October 2024, as required by the EPA.
The city used historical records to identify as many service line materials as possible, and sent 10,000 letters to property owners who might have lead service lines in the summer of 2022 asking them to complete identification tests of their pipes.
The rule also requires that lead lines be replaced over the next decade.
City staff have been discussing this EPA rule and the impact to the city since 2022 and the crux of the issue is that city code states a property owner is responsible for the service line from the main to the property.
But, under the new EPA rule, the city could be penalized for the number of lead, or unknown, service lines, which, if fined, would be a cost borne by all city ratepayers.
Lines that are unknown in the inventory are counted as lead and must also be replaced unless they are otherwise identified.
Calob Marquis, the city’s water infrastructure division manager, told The Electric that the corrosion control project is just one of the federal mandates the city is required to complete, and it precedes the next major requirement: the full replacement of all lead service lines over the next decade.
Marquis said city staff are hopeful that by informing residents about the EPA mandates, and with ratepayers completing their service line inventory information, the city can mitigate the overall costs associated with the mandates.
The city is completing its lead service line replacement pilot project that included 13 locations across the city.
In April, the city approved a $327,440 contract to Capcon LLC for the project, which is being funded by the city’s water utility fund through a Montana Department of Natural Resources and Conservation State Revolving Fund loan with 60 percent principal forgiveness.
The pilot program had been discussed during city commission work sessions since 2023.
The state’s loan fund is being funded through federal infrastructure funding.
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That means the city will use the loan to cover 60 percent of the cost of replacing the known lead lines and the remaining 40 percent will be shouldered by the city water fund, or user fees.
In early 2023, staff initially planned to use the federal funds that are being funneled through the state’s revolving loan fund, coupled with federal Community Development Block Grant funds, to directly reimburse private property owners for replacing their lead lines, and contracted with AE2S to assist with the loan, homeowner coordination, design and construction management for the pilot.
But, DNRC determined that city funds were required to reimburse the remainder of the loan after forgiveness instead of CDBG or property owner funds.
So by the fall of 2023, commissioners approved a resolution allowing for water funds to be used to reimburse the costs of the project.
In September 2024 and May 2025, staff presented to commissioners that they intended to move forward with the pilot project to replace some lead lines using the city water fund, which is water utility fees.
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During their Sept. 2 meeting, commissioners approved an agreement that staff used for the project with up to 20 property owners and DNRC, as well as the Department of Environmental Quality, which required the agreements for property access.
Commissioners approved the DNRC loan terms earlier this spring, with a total loan budget estimated at $397,240, which includes $327,440 for construction and $69,800 for design.
With 60 percent principal foregiveness, the loan outstanding is $158,896 and the annual payment on the 20-year loan with a 1.5 percent interest rate is an estimated $9,300, according to the city staff report.
During a September commission meeting, Chris Gaub, city public works director, said that the city may use a similar process for mandated replacements in the future.
In September, Commissioner Rick Tryon asked why ratepayers should cover the cost to replace someone’s line, to which Gaub said “it is a calculated pilot project,” to replace up to 20 lines to be ready for the EPA rules.
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It’s a similar conversation the city has been having since 2022.
City staff have been working to inventory all existing service lines within the city limits, since the EPA will hold the city accountable for any lead lines and unknown lines are treated as though they are lead under the rules.
Gaub said that if the city ends up with 1,000 lines that need to be replaced under EPA rules, it would be the city that gets fined for violations, not the individual property owners.
“That’s a tension that we’ve talked about since almost day one,” Gaub said.
Tryon said in September that he may not vote for it since it “looks to me like some people are getting a good deal and some are getting screwed.”
He asked how the city picks the properties for the pilot.
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Gaub said the city had asked for volunteers for sampling, which is another increased requirement under the new EPA rules. Twenty property owners had agreed to that.
Of those, 13 had signed the agreement for the replacement pilot and were ready to go, as of September.
Gaub said in the fall that staff was working to find another seven property owners, but if they didn’t, they may stop with those 13.
The project jsut completed and funded under the contract included 13 properties.
Staff had briefed commissioners on the EPA rule and the proposed pilot program during their May 2025 work session.
They were planning for the EPA to require that lead lines be replaced over 10 years and for Great Falls, staff said in May 2025 that the best case scenario was having to replace about 1,100 lines, at $15,000 each for $17 million over 10 years, equating to a roughly $7 monthly water bill increase for all city customers.
Worst case scenario is that the city has to replace the roughly 4,900 lines that are either lead, copper or unknown, over the next decade at a cost of about $73.5 million, or an additional $28 monthly on a water bill.
That’s why staff has been working to identify service lines citywide, sending letters, making phone calls and going door to door.
Jesse Patton, city engineer, said in May 2025 that staff wanted the public to be aware of the costs.
He said if a resident tells them no four times, and staff documents it, that water line comes off the count against the city under the EPA rules.
But staff has to monitor that property and every time it changes hands, they have to go through that time-consuming process again, Patton said.
The EPA rule also requires the city to submit to DEQ and post on the city website replacement plans detailing how they’ll identify remaining unknown lines, conduct replacements, communication, prioritization of replacements, a funding strategy, citing specific city laws and have information on how to assist those who can’t afford to replace their own lines.
That plan has to be updated annually and staff said in May 2025 that the pilot program would help lay that foundation.
The EPA rule requires annual letters to nonconforming locations, and beginning in 2027, the city has to document four required replacement attempts, which resets if property ownership changes.
Mark Juras, of city public works, said in May 2025 that other cities have hired consultants to prepare for the new EPA rules, but Great Falls staff started early, so they were ahead but needed residents to respond regarding their service line type.
During the May 2025 meeting, Tryon asked if the city was planning to spread the cost across all ratepayers to replace the nonconforming lines.
Juras said, yes, that was the plan under an EPA-mandated replacement schedule.
“That’ll go over well,” Tryon said.
Juras said in May 2025 that it was “uncertain at this time” what would happen if the city doesn’t meet the EPA requirements, but staff believes it’s very likely the city would be fined.
Nationwide, ratepayers are being asked to fund these upgrades without much federal funding to meet the requirements, Juras said.
