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 in homes built or plumbed between 1970 and 1985 with copper pipes and lead solder.
Water from the Bull Run watershed is naturally corrosive, increasing the amount of lead and copper that dissolves into drinking water. This is more likely to happen when water has been sitting in home plumbing for several hours.
The Portland Water Bureau’s corrosion control treatment reduces corrosion in plumbing by adding sodium hydroxide, which increases the pH of the water. This pH treatment can reduce the presence of lead in tap water by more than half.
High-Risk Home Monitoring
Twice each year the Portland Water Bureau and regional water providers in the Bull Run service area monitor for lead and copper in tap water from a sample group of more than 100 homes. These are homes in the Bull Run service area where the plumbing is known to contain lead solder, which is more likely to contribute to elevated lead levels. These houses represent a worst-case scenario for lead in water.
Samples are collected after the water has been standing in the household plumbing for more than 6 hours. If lead levels exceed 15 parts per billion*, the action level established by the Environmental Protection Agency, in more than 90% 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