The Portland Water Bureau will ask the Portland City Council next week to approve a pilot program that would treat the city's drinking water for corrosion to reduce water customers' exposure to lead.

Portland's water from the Bull Run watershed has a low enough pH level that it can leach lead from old pipes and fixtures. Adding chemicals that don't harm human health can make the water less corrosive.

The decision to try doing that comes after the Environmental Protection Agency instructed Portland to review its lead-prevention efforts, the state ordered the city to come up with a plan to immediately reduce lead levels in drinking water and an Oregonian/OregonLive investigation found that regulators turned a blind eye to Portland's lead problems.

Federal regulators require water providers to ensure lead levels remain at or below 15 parts per billion. Portland exceeded that measurement 10 times. It exceeded federal standards for amounts of lead in drinking water at least twice in three years.

"Exceedances of the federal action level for lead in water in Fall 2013 and Fall 2016, have highlighted the need for further treatment," bureau officials wrote in a press release Thursday.

The bureau's treatment program pilot aims to adjust the water's pH level, which is commonly done by adding sodium carbonate and CO 2 . Treating the water is less expensive than replacing home plumbing, an option the water bureau says does not meet a federal Lead and Copper rule anyway.

"Improved treatment will provide all customers with any sources of lead in their household plumbing equal access to its benefits at a fraction of the cost," a report sent to stakeholders from the water bureau said.

Such treatment could change the "feel" of the water, the report said.

"We have begun to reach out to many of our large users such as breweries, manufacturers, bakeries, dialysis clinics and bottlers to inform them of the potential changes," the report said. "So far the potential impacts are not expected to significantly impact their operations."

If the city approves the enhanced treatment program, it could take as long as 5 1/2 years for the water bureau to put the program into place.

--Jessica Floum

503-221-8306