Lead and copper enter drinking water primarily through plumbing materials. In the Portland area, lead in drinking water is primarily a result of household plumbing materials, especially when built or plumbed between 1970 and 1985 with copper pipes and lead solder.
The Portland Water Bureau’s corrosion control treatment reduces corrosion in plumbing by adding sodium hydroxide, which increases the pH of the water. Corrosion treatment has reduced the presence of lead in tap water by more than half.
Untreated water from the Bull Run Watershed is naturally corrosive, which could increase the amount of lead and copper that dissolves into drinking water.
In 1994, Portland completed a corrosion control study that indicated raising the pH to 9.0 and adjusting alkalinity to 20 mg/L could provide additional reduction of lead in water. The Portland City Council directed the Water Bureau to look at alternative methods to reduce exposure to lead. The result is Portland’s current compliance program, which includes corrosion control treatment to adjust pH to 8.0.
In 2014, in anticipation of changes to the water system, the Portland Water Bureau secured funding to begin a water quality corrosion study. That study will inform potential changes in the future. We expect results in the summer of 2017.
In March 2016, EPA Region 10 contacted the Portland Water Bureau to discuss lead and corrosion control. As a result, the bureau requested meetings to discuss the issue further with OHA and EPA held in April and August 2016. In those meetings the bureau presented Portland’s approach to complying with the Lead and Copper Rule and outlined its May 2014 corrosion control study.
The bureau is also evaluating treatment options that are available to achieve pH 9 and an alkalinity of 20 mg/L. Any recommendation for a change in treatment will be presented to the full City Council for review and approval.
Links to relevant communications, including the presentations from the April 2016 meeting, are provided below.
- 1997 letter from Oregon Health Authority to Portland Water Bureau approving the LHRP as optimal corrosion control treatment
- 2016 letter from Portland Water Bureau to Oregon Health Authority to request a meeting to discuss Lead and Copper Rule compliance
- 2016 letter from the Environmental Protection Agency to Oregon Health Authority regarding the 2016 letter from PWB to OHA
- April 2016 presentation by PWB to OHA and EPA
- August 2016 presentation by PWB to OHA and EPA
Twice each year the Portland Water Bureau and regional water providers in the Bull Run service area to monitor the effectiveness of corrosion control for lead and copper in tap water by testing a sample group of more than 100 homes. These are homes in the Bull Run service area where the plumbing is known to contain copper pipes and lead solder, which is more likely to contribute to elevated lead levels. These homes represent a worst-case scenario for lead in water.
Sample collection instructions for the homeowners follow EPA-recommended procedures. Samples are collected by the homeowners after the water has been standing in the household plumbing for more than 6 hours. When samples are returned to the Water Bureau, they are put through a screening process to ensure they meet the regulatory requirements before being sent to the lab. This ensures that the results from all the samples analyzed by the lab will be used to determine compliance with the Lead and Copper Rule and will not be invalidated due to sampling issues. If lead levels are over 15 parts per billion*, the action level established by the Environmental Protection Agency to monitor the effectiveness of corrosion treatment, in more than 10% of these homes, the Portland Water Bureau notifies its customers and performs outreach and education to those most at-risk for lead exposure.
*One part per billion corresponds to one penny in $10,000,000 or approximately one minute in 2,000 years.
High-Risk Home Monitoring Results