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The Lead and Copper Rule, published in 1991, regulates how drinking water systems manage lead and copper that may enter into drinking water from plumbing. It requires that large systems treat drinking water to make it less corrosive, which reduces the amount of lead and copper from household plumbing that dissolves into drinking water.

Since 1997, the Portland Water Bureau has had a compliance approach that includes treating the drinking water to reduce lead and copper by adding sodium hydroxide to increase the pH of the drinking water to make it less corrosive. This treatment has resulted in up to a 70 percent reduction in lead in water levels at customer taps.

Since the Lead and Copper Rule was enacted, science has shown there are no safe levels of lead exposure, as a result improvements in the treatment are underway to further reduce lead in drinking water levels at customer taps. These improvements are scheduled to be in place by April, 2022. In the meantime, interim actions will be taken to further protect public health as the bureau implements Improved Corrosion Control Treatment.

Benefits of Improved Corrosion Control Treatment

• Reduces the risk of lead at the tap. Studies have shown that additional treatment is the most effective means of further reducing lead in water from home and building plumbing.
• Increase stability and consistency of the water quality. Corrosion control treatment can result in a more consistent and stable pH in the system.